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Centennial Year Volume 93, Number 1 January-March 1979
The Ottawa Field-Naturalists’ Club
FOUNDED IN 1879
Patrons Their Excellencies the Governor General and Madame Jules Léger
The objectives of this Club shall be to promote the appreciation, preservation and conservation of Canada’s natural heritage; to encourage investigation and publish the results of research in all fields of natural history and to diffuse information on these fields as widely as possible; to support and cooperate with organizations engaged in preserving, maintaining or restoring environments of high quality for living things.
The Members of Council are listed on the inside back cover.
The Canadian Field-Naturalist
The Canadian Field-Naturalist is published quarterly by The Ottawa Field-Naturalists’ Club. Opinions and ideas expressed in this journal, however, are private and do not necessarily reflect those of The Ottawa Field-Naturalists’ Club or any other agency.
Editor: Lorraine C. Smith
Assistant to the Editor: Donald A. Smith Book Review Editor: J. Wilson Eedy
Associate Editors
C. D. Bird A. J. Erskine David P. Scott E. L. Bousfield Charles Jonkel Stephen M. Smith Francis R. Cook Charles J. Krebs Robert E. Wrigley
George H. La Roi
Copy Editor: Marilyn D. Dadswell Chairman, Publications Committee: J. K. Strang Production Manager: Pauline A. Smith Business Manager: W. J. Cody
Subscriptions and Membership Subscription rates for individuals are $10 per calendar year. Libraries and other institutions may subscribe at the rate of $20 per year (volume). The Ottawa Field-Naturalists’ Club annual membership fee of $10 includes a subscription to The Canadian Field- Naturalist. Subscriptions, applications for membership, notices of changes of address, and undeliverable copies should be mailed to: The Ottawa Field-Naturalists’ Club, Box 3264, Postal Station C, Ottawa, Canada KIY 4J5. Second Class Mail Registration No. 0527 — Return Postage Guaranteed.
Back Numbers Most back numbers of this journal and its predecessors, Transactions of The Ottawa Field- Naturalists’ Club, 1879- 1886, and The Ottawa Naturalist, 1887-1919, may be purchased from the Business Manager.
Business Manager: Mr. W. J. Cody, Box 3264, Postal Station C, Ottawa, Ontario, Canada KIY 4J5
Book Review Editor: Dr. J. Wilson Eedy, R.R. !, Moffat, Ontario LOP 1J0
Coordinator, The Biological Flora of Canada: Dr. George H. La Roi, Forestry Sciences Laboratory, 3200 Jefferson Way, Corvallis, Oregon, USA 97731 (address valid until August 1979).
Address manuscripts on birds to the Associate Editor for Ornithology: Dr. A. J. Erskine, Canadian Wildlife Service, Box 1590, Sackville, New Brunswick E0OA 3C0
All other material intended for publication should be addressed to the Editor: Dr. Lorraine C. Smith, R. R. 3, Stittsville, Ontario, Canada KOA 3G0
Urgent telephone calls may be made to the Editor's office (613-996-5840), the office of the Assistant to the Editor (613-231- 4304), or their home on evenings and weekends (613-836-1460), or to the Business Manager's office (613-995-9461).
Cover: Since the Club was founded in 1879, it has published a journal under three successive names. Covers bearing the two names preceding the present one are illustrated. Left, Ortawa Field- Naturalists’ Club, Transactions, published for 1879 to 1886. Right, The Ottawa Naturalist, published from 1887 to 1919; it bore this cover design only between April 1918 and March 1919.
THE CANADIAN FIELD-NATURALIST
Volume 93 1979
CENTENNIAL YEAR THE OTTAWA FIELD-NATURALISTS’ CLUB
OTTAWA CANADA
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The Canadian Field-Naturalist
Volume 93, Number | January-March 1979
One Hundred Years in Perspective — the Changing Roles and Objectives of The Ottawa Field-Naturalists’ Club
ROGER A. FOXALL President, The Ottawa Field-Naturalists’ Club, January 1977-January 1979
Following an invitation to members of the Ottawa Literary and Scientific Society, “fully forty gentlemen attended the meeting held on the 19th March, 1879. After a lengthy discussion as to the form the organization should take, the Ottawa Field-Naturalists’ Club was born.”
The quotation above is from the first historical sketch of the Club, taken from the 1880 Annual Report when the Club was fully one year old. Since then there have been several articles describing the many memorable people and events that add up to the varied and fascinating 100-year history of our Club. A series of historical articles is currently being published in Trail & Landscape. The aim of this message is not to provide another summary of people or events, but to review instead the ways in which the Club’s functional role and objectives have changed over time and to present a personal view of our present role and objectives in terms of future needs.
In the beginning, the objective of the Club was stated simply as “the study of the Natural History of this locality.” The raison d’étre, however, was more explicit in an 1884 summary:
“The value of these studies cannot be over-estimated for, from their very nature, they are most beneficial both to mind and body, while, from an economical point of view they are no less important . . . . The future of Ottawa is in large measure dependent upon the development of the vast stores of minerals contained in the surrounding districts, and which are as yet almost unexplored. The manifold uses and demand for all vegetable products make it necessary that the nature and habits of plants should be closely studied, as well as those of the countless myriads of insect foes which deprive the cultivator of so much of his hard-earned gains... . It gives very great satisfaction to the members of the Council to find that the Club is being gradually recognized as a source of reliable reference on all these matters.”
So the objective in part was the study of natural history to assist the economical development of the Ottawa area. Times have indeed changed! A specific example of success in this direction was the advice given to the Ottawa Granite Company that within a few miles of the city there existed an outcrop of quartzite deposits just as good as quartzite then being imported from New York State. This advice led to successful commercial exploitation of the deposits.
Although economic development of the Ottawa area was one aim of the Club, another was to popularize the study of the different branches of natural history and thereby increase appreciation of nature. On the local scene this entailed programs of organized studies, excursions, lectures, and generally spreading the good word. By the thirtieth anniversary, Club membership had increased from the initial 40 to over 300. Increasingly, however, the Club’s successes led to recognition throughout the Dominion, and its role began to broaden from that of a strictly local club towards
2 THE CANADIAN FIELD-NATURALIST Vol. 93
that of a national society. In an 1893 The Ottawa Naturalist, the editor found it necessary to state, “Although the scope of the Club’s work has been gradually widened to receive the benefits of investigations made by its members wherever they may be located, the special work for which it was organized must stili merit the chief attention, and although much has been observed and recorded of the Natural History of Ottawa, there still remains vastly more to be done.” But the transformation accelerated! A series of 42 nature study articles was written for The Ottawa Naturalist by leading Club members, and between 1903 and 1908 a total of 238000 separate copies was distributed to schools and colleges across Canada. Such was the success and expanding influence of the Club that Ottawa’s Evening Journal (although perhaps a little biased) found it appropriate in 1908 to state that “today The Ottawa Field-Naturalists’ Club is the greatest institution of the kind in the entire continent of North America.”
Partly because of the Club’s campaigns and the travels of Club members, but mainly because of a general increasing interest in nature, similar organizations were established in several cities across Canada. Increasingly, the need developed for a publication covering the natural history of all of the Dominion, until in 1918 the Foreword to the last volume (32) of The Ottawa Naturalist announced:
“The time has come, however, when a local periodical of this nature is inadequate and the Dominion requires a more creditable and representative publication for the record and dissemination of the results of scientific research. The Ottawa-Naturalist, with its already established position, long and honorable history and scientific standing, seems a logical nucleus from which such a publication should be developed.” The first issue of The Canadian Field- Naturalist was published in April 1919. This event in the Club’s 40th year marked the end of a lengthy transition and formalized the dual role of the Club — a local natural history club and a national society. Somewhat earlier, in October 1912, the objectives of the Club had been expanded significantly to reflect the two roles: To foster an acquaintance with and a love for nature; to study especially the natural history of the Ottawa District; to encourage investigation and to publish the results of original research in all departments of natural history; to arrange for out-of-door excursions during the summer months; to provide free lecture courses during the winter months; and ina general way to render assistance to students or others interested in Nature Study. With one significant exception, to which I will refer below, these objectives remained unchanged until 1972.
Unfortunately the success of the Club’s first 40 years was to be followed by a 30-year period during which many difficulties were encountered. Until about 1923, the Club received a grant from the Ontario Department of Education that contributed significantly to the sustenance of The Ottawa Naturalist and later The Canadian Field-Naturalist. \ronically, post-war economies led to cancellation of the grant when it was needed most, for the creation of The Canadian Field- Naturalist placed a significant burden of responsibility on the Club and all its members. Without the grant, many more members were needed to provide financial stability. But the growth was too slow. In 1934 P. A. Taverner, Chairman of a Special Committee on Membership, issued an appeal to all Canadian naturalists to boost membership. A reduction in size, from 24 to 16 pages an issue, and other parsimonious economies had been tried, but still the year-end balance was negative. The journal survived, of course, but for many years the fight for The Canadian Field-Naturalist’s survival represented the principal objective of The Ottawa Field-Naturalists’ Club.
The difficulties in maintaining the national role were paralleled by difficulties with the local role. Here, analysis is more difficult. We can perhaps rationalize the decreasing enthusiasm in terms of two gradual developments. The early years of systematic, detailed studies of local natural history must have represented a frontier-like challenge — new knowledge was easily acquired and each discovery, be it a new species of plant, insect, bird, or butterfly, contributed to the developing picture. But the acquisition of new knowledge makes further discoveries just that much more difficult. Members would have to travel further and look harder, and greater expertise was needed. But why
1979 FOXALL: PRESIDENT’S MESSAGE 3
try so hard? The initial objective, to assist in the economic development of Ottawa, was surely less important now. The urgency of acquiring knowledge in support of conservation and preservation to slow down development was not yet recognized. For whatever reasons, it is a fact that emphasis on studying the local natural history declined to the point that in 1947, the objective “to study especially the natural history of the Ottawa District” was removed from the Constitution. Although excursions and lecture programs continued to foster and sustain members’ interests in local natural history, the membership grew slowly and even declined for several years.
In retrospect it seems likely that the Club’s surviving the difficult 30 years can be attributed to its dual role. For without the local membership, The Canadian Field-Naturalist might have failed financially, and without the responsibility of continuing The Canadian Field-Naturalist, the local club might have failed for lack of sufficient motivation.
The last 30 years, 1949-1979, have also been characterized by significant changes, but the story is a happier one. The Canadian Field- Naturalist has steadily developed into a scientific journal of both national and international repute — a journal almost unique in the world for its breadth and standard of scientific natural history reporting. The content has evolved also. The studies reported have progressively become more sophisticated as new knowledge requires increasingly more detailed examination of natural phenomena. Other, less formal journals and club magazines are now published and these provide media for reporting studies and findings of more local importance. There is no doubt that these evolutions have resulted in The Canadian Field- Naturalist becoming of lesser interest to many local members. But the need for The Canadian Field-Naturalist is at least as great today as it was in 1919, and, through its continuing support, The Ottawa Field- Naturalist’s Club is playing a very valuable role in the reporting of Canadian natural history.
The continuing decrease of Ottawan content in The Canadian Field- Naturalist and the need to regenerate the local Club, led to the start, in 1949, of a Club Newsletter for local members. Steadily the pendulum swung back as successive Presidents and Councils worked very hard to rebuild. It was not easy, as illustrated by the anguished appeals in the Newsletter of Chairmen of Excursions and Lectures urging members to attend the many walks and talks that were being arranged. But the rebuilding succeeded and by the late 1960s the local Club had regained much of the status and drive of the early period. As a Canadian Centennial project, the Club upgraded the Newsletter to become the magazine Trail & Landscape. For the last eleven years, the staff of Trail & Landscape has succeeded in producing an excellent, informative magazine that focusses on local sightings, events, and issues. Sometimes serious, sometimes lighthearted, but always highly readable, Trail & Landscape plays an important role in generating and maintaining the enthusiasm of local members.
Somewhat surprisingly, in retrospect, natural history organizations throughout North America were slow to recognize that man’s rapid development and exploitation represented a serious threat to all natural environments and living things. In the beginning, The Ottawa Field-Naturalists’ Club had ~ worked in support of economic development. When, later, favorite areas such as Dow’s Swamp were taken from us, no organized howls of protest were heard. Such things were taken for granted as a normal result of development. But by the mid-1960s organizations everywhere recognized the threat to what had seemed before to be an apparently infinite environment. The battle began to preserve for future generations those areas that had so far survived exploitation, to control thoughtless pollution, and to prevent the indiscriminate use of chemicals that threatened wildlife. In 1972, the Club’s objectives were rewritten to reflect the new motivation:
To promote the appreciation, preservation and conservation of Canada’s natural heritage; to encourage investigation and publish the results of research in all fields of natural history and to diffuse information on these fields as widely as possible: to support and cooperate with organizations engaged in preserving, maintaining or restoring environments of high quality for living things.
On the national scene, the new emphasis is being supported by the publication in The Canadian Field- Naturalist of, for example, excellent papers on the effects of chemicals such as PCBs in the environment, and the internationally acclaimed issues on the status of the Peregrine Falcon. The
4 THE CANADIAN FIELD-NATURALIST Vol. 93
local Club established a Conservation Committee of Council and became heavily involved in the battles to defend the Mer Bleue and Gatineau Park, and more recently to defend many other natural areas of the Ottawa-Carleton Region.
Today, the Club continues its dual role, publishing The Canadian Field- Naturalist on behalf of all Canadian naturalists, and performing the functions of a typical local natural history club — arranging excursions and lectures, publishing a local magazine, and attempting strenuously to protect from further development many areas of significance to natural history.
A successful one hundred years? Certainly! The Club’s founders would surely be pleased with what transpired from that first meeting on 19 March 1879. The Club has evolved to meet the needs of naturalists over a period of immense change in Canada, thousands of people have benefited directly from their association with it, and many more thousands have benefited indirectly from its achievements. More could have been done, particularly on the local front, for it is surely ironic that a club formed one hundred years ago to study Ottawa’s natural history has been forced to scramble hurriedly during the last few years trying to acquire sufficient knowledge of local areas (some only ten miles from Parliament Hill) to support their preservation and conversation.
Although the celebration of our Centennial Year will be largely retrospective, some time should be spent thinking about and discussing our current roles and objectives in terms of future needs. Some predictions can be made with a reasonable degree of confidence. These are:
— the need for The Canadian Field- Naturalist, or an equivalent journal, will continue into the foreseeable future:
— the pressure on natural environments and living things will continue to increase, in the short term at least;
— the potential for increasing public interest in and concern for natural history will increase as the amount of leisure time continues to increase: and
— in the longer term, leisure activities, if uncontrolled, will become a serious threat to natural environments.
Let us now examine our objectives in these terms. The second objective, “to encourage investigation and publish the results of research in all fields of natural history and to diffuse information on these fields as widely as possible,” is certainly appropriate. Although several local Club members have expressed the opinion that The Canadian Field- Naturalist has become too “professional” or too “scientific” to be published by a club largely made up of amateur naturalists, I remain convinced that the Club should continue to publish The Canadian Field-Naturalist on behalf of all Canadian naturalists at least until it is demonstrated that another organization could provide it a better home.
Similarly, the third objective, “to support and cooperate with organizations engaged in preserving, maintaining or restoring environments of high quality for living things,” will continue to be appropriate. Our recent performance in support of this objective has not been outstanding and the Club should concentrate on becoming more involved with other organizations. To attempt to do this effectively on a national scale would be unrealistic, but more could and should be done to promote effective cooperation with organizations in Ontario and Quebec.
The first objective, “To promote the appreciation, preservation and conservation of Canada’s natural heritage,” sounds impressive but is as a separate objective, the least realistic for The Ottawa Field-Naturalists’ Club today or in the future. We do support it to some extent by publishing The Canadian Field-Naturalist and by cooperating with other organizations, but some modification of the objective appears necessary if the Club is not to pretend it is trying to duplicate the function of a large national conservation organization such as the Canadian Nature Federation. This is not to say that I feel The Ottawa Field-Naturalists’ Club should become overly parochial, but I do think that the stated objectives of any organization must represent specific, realistic challenges that can be pursued effectively.
Finally, | would urge the Club to reintroduce the objective “to study especially the natural history of the Ottawa District,” with this or some similar wording, to reflect the localized nature of most of
1979 FOXALL: PRESIDENT’S MESSAGE 5
our activities and the need to continue increasing our knowledge of the district. During the conservation battles of the last few years, local planning bodies have come to recognize the Club as the authoritative source for much of the data on which to base decisions affecting the natural environment. This recognition is due entirely to the hard work of relatively few members. Past appeals to members to help in this endeavor by turning out for inventory-type excursions have largely failed. If the Club is to succeed in meeting the challenges for the future based on the predictions listed above, it must surely focus again on the original objective, chosen on 19 March 1879 — “the study of the Natural History of this locality.”
Biology — The Unknown Science?
YORKE EDWARDS British Columbia Provincial Museum, Victoria, British Columbia V8V 1X4
Biology is a science largely unknown to the people of the world. If life is the most important “thing” on Earth, this is a strange condition. The disturbing result is that not only is the man in the street largely ignorant in all things biological, but also that decisions on how man will treat our life- support system — Planet Earth — are made without biological understandings. Biology is largely missing as general knowledge, hence also as an automatic aid to intelligent decisions. When, on occasion, biology does happen to be given its day, there is no background of accepted status to give it weight. Biology has little hope of being valued or even understood if it is to surface in public affairs only at moments of crisis.
Scientists do a remarkably good job of keeping the public uninformed. This is partly because the public is rather narrow-minded about what is important, which creates some reluctance on the part of scientists to become too visible. But then, of course, a more informed public might be more understanding. When we add to this picture the high proportion of scientists unable to be very informative about their work to almost everyone, the reasons for science’s isolation from the man in the street are clear and appear to be formidable.
The poor record of scientists being intelligible and convincing in public seems to be programmed that way by the nature of both today’s science and today’s scientists. Science today is largely concerned with exploring smaller and smaller bits of our world, with things beyond the awareness of everyday human experience. Scientists lead this trend, but few are helping to put the bits together into more understandable wholes. It is the era of the specialist. By contrast the generalist in science has become rare, which I am convinced endangers both science and the world.
The generalist in science is a necessary companion to the abundant specialist who is traditionally learning “more and more about less and less.” The need is not just to assemble what we know about the world into forms meaningful to many, it is also a matter of possessing the resulting wisdom necessary for survival.
Man’s wildly compounding knowledge has him more and more in control of his support system Earth in an accelerating use of this control that is quite out of control. Science feeds the largely destructive trend. Few people, including most scientists, can glimpse what is really happening, for the quality and quantity of the effects are beyond the sensory capacities of most people. Understanding, acquired from those few who do understand, is the only hope of self control, understanding that comes from broad insights into the world and how it functions. Science must do a much better job of arranging “more and more of less and less” so that bit plus bit becomes a somewhat visible, somewhat accurate, somewhat understandable whole.
Many scientists consider the discovery of truth to be their sole justification. For example, they regard the basic discoveries in atomic physics as standing alone; atomic warheads are therefore other men’s burdens, not those of the pure scientists. This assumes it not true that achieving atomic fission made Hiroshima’s devastation probable, even inevitable in the political climate of the time.
In most respects all of us have minds not much changed from those of ancestors in Ice Age caves. The products of science available to us all are power in the hands of ignorance. If science put the power there, and continues to do so without adding very effectively the controls of understanding, we are surely building systems for our own destruction. Only science can correct this situation. We need a new morality in the sciences, which would result in major efforts to make science and its influence on Earth understandable to those outside the ivory towers, and to those in them too, for most scientists do not understand most science.
There is a modern myth in our culture that the scientist is among the most brilliant and wise of men, understanding the world as few others do. Some scientists believe this. But there are many
6
1979 EDWARDS: GUEST EDITORIAL 7
people who do not, and in fact, from his specializations, and from his frequent mental and physical isolation from the worlds that most people experience, there is an emerging image in our society of the scientist being rather dangerous.
Inevitably, dedicated specialization results in tunnel vision. Neither the specialization nor the resulting narrow view of the world are by any means confined to scientists in our society, nor is the trend for these many specializations to be increasingly specialized. But they are relatively unimportant outside of science. It is specialization within science itself that can keep people awake at night.
Science has given us formerly unbelievable powers and capabilities at the price of mushrooming humanity in a disintegrating support system. If it is not already too late, the end of irresponsible science is the only cure, and then only if irresponsibility is replaced by responsibility, not just for tomorrow’s new problems but for yesterday’s legacy of old ones as well.
It is fashionable to say that “It was the side-effects that got us.” There can be no clearer evidence of our narrow views. “Side-effects” are a tunnel-vision illusion, for the broad view will see only BCILCCtS:
I have begun this essay with the broadest possible sweeps quite by plan. My resulting generalizations contain many of the “part truths” and “too general” sorts of “facts” that drive most scientists into ever deeper specializations with their attractively simple foci of study. In disciplines properly requiring the greatest possible degrees of accuracy, the uncontrolled drift of scientists toward the high accuracy areas is perhaps predictable. But I wonder if this is both science’s blind alley, and Earth’s sentence to increasing impoverishment of its life. While the sciences choke on ever increasing flows of new detail from examining the parts of the world, not many scientists are putting the pieces together into meaningful wholes of knowledge. We need more syntheses by more generalists, more generalization even at the calculated risk of less accuracy.
The need is not so much for fewer specialists as it is for more generalists, not so much for less publishing of science as for more interpretation of science where there is recognition of the value of generalization that may be accurate enough to be of great value, while also being uncertain and perhaps therefore inaccurate to some degree.
Conquering the tsetse fly “problem” in Africa is receiving much research. The tunnel vision approach would focus simply on eradicating flies as a relatively simple biological problem. The generalist might be aghast at such efforts in view of the vast ignorance of what the power to destroy the tsetse would really accomplish through chain reaction and time. Tunnel vision sees only flies, with perhaps another vision of people happily eating more cattle. A broader view might see over a quarter of a continent an end result of human poverty and misery in rapidly expanding deserts that mark the end of rich faunas and floras once containing reasonably successful people. The innocence | of dropping sucha powerful force as easy tsetse eradication into the lap of a humanity largely blind to the terrible powers involved has many parallels in history, where seemingly small additions to the capability of man has resulted in world changes too big for most people to see, and too drastic for those touched by it to understand.
Science has rarely been in the arena of public debate, expounding its discovered truths. Without science participating in human affairs with a vigor equal to its unique capability for discovery, what hope is there for wise choices? What hope for future life in high quality environments?
Not always do the issues have the potential inflation factor of tsetse flies or nuclear fission. But the effects of lesser tinkerings add up, with overharvesting here, mercury waste there, disease eradication somewhere else, each with their chain reactions. Not long ago I read an enthusiastic article froma Canadian botany department assessing the harvest potential from the kelp growing along the British Columbia coast. A new industry was about to be born, and the facts were proclaimed as if from the local Chamber of Commerce. On impulse, I penned a note to the author asking to what extent the intended harvest would be also habitat removal to the rich and specialized fauna of the kelp “forests,” and what animal species were involved. The reply was a refreshingly candid admission that the thought had not occurred to him. Tunnel vision was perhaps quite properly his view of the kelp beds,
8 THE CANADIAN FIELD-NATURALIST Vol. 93
but there seemed to be no other view involved. No one had considered effects and chain reactions.
I work in one of Canada’s larger museums with specialists in history, zoology, botany, ethnology, archaeology, and other fields. When I first examined this small community of mixed disciplines, I was impressed by the isolation from the others in which each group worked; but I became more impressed later on those rare occasions when cross-communication between two of them triggered an exciting and enlightening experience for both. Acommon language of biology bound together the life sciences, and an ecological dimension common to biology and anthropology gave them common ground from which to exchange ideas. But history was different; for traditional reasons it was unable to comprehend either biological or ecological concepts, so was unprepared to consider them of use. This was the most impressive museum experience ofall, and I have tried to understand it, not just for reasons of improving a museum, but for its possible deeper meanings. The new and popular interest in ecology has not touched the historians about me, at least not as historians. To converse with them I must drop my ecological view of the world and lean heavily on my everyday experiences with people interested simply in experiences with people. This sort of superficial observation of the human scene has been man’s need and entertainment since man became man, perhaps before, and it seems that traditional history as a discipline is largely a formalized version of this trait. A scientist might conclude that attempts to explain history without using the knowledge of biology and ecology must result in very limited understandings. A historian may counter that to record the passing scene 1s enough; let others try to explain it.
The science-less view of history must be largely the view of the world as seen by most people. There is little concern with cause and effect, the only part of the world worth noting being people. Their successes and failures, if explained at all, result from their own interactions, chance, and the supernatural. Modern history of course has its ecologically oriented historians, or so the literature would suggest unless they are instead scientists trespassing in history. Nevertheless, science is not a useful part of traditional history, not to the extent of its being a constant means of understanding the past.
This ignoring of man’s supreme accomplishment in recent times — scientific knowledge — in understanding the world is the standard human condition. We gladly accept the wealth and ease that science has given us. We eagerly learn to apply the directions of science for achieving health and comfort and riches from our environments. We spray the aphids on a bush, and thereby unknowingly poison a hundred other kinds of creatures, including ourselves. We pour chemicals of unknown capability into a sewer, for safety, and thereby take food in the form of fish from the mouths of a thousand people. We remove a rich forest with machines from an endless list of discoveries, and for quick profit burden future generations with square miles of sun-baked wastelands. To learn to exterminate a fly may be, unknowingly, to learn how to create deserts over half a continent. We are given power far greater than we realize, far more given to unexpected chain reactions than we can guess, by a science not doing the important part of its job. The brilliance that gives inventions and discoveries must come from a system discovering and disseminating also some understanding of the impact of those inventions and discoveries upon the face of Earth.
The world needs generalists in science, using new approaches in science, to discover the true meanings of its discoveries, and to report them in useful form giving the sure, the probable, and the possible effects of their use. Only such synthesizers, at all levels of science, can scientifically reconstruct whole animals, rebuild whole habitats and whole landscapes, putting aggregates of knowledge back into the public reach so that whole things, or at least meaningful parts of things, are understood as far as men understand them. This is not easily done. That is why science fails to do it. By the standards of accuracy demanded in most sciences these reconstructions will have some inaccuracy. If this is unavoidable, it must become acceptable insofar as its accuracy is useful, because there is not just a general intellectual need for non-scientists to see more sums of knowledge, there is some urgency since our science and technology seem to have us programmed in several ways to self- destruct.
The challenge of evolving effective methods for such a prevalent new dimension to science may
1979 EDWARDS: GUEST EDITORIAL 9
not be the main problem. Present scientific circles frequently regard as somehow second class those of its scientists that put much effort toward being understood in lay society. It is almost as if there was a cult for obscurity. Perhaps we have a long way to go.
Science must of course be encouraged to pursue the obscure. But let it also learn to reassemble the parts. Biology is not presently a force in world affairs because it does not communicate well, at least not at the level of public understanding. Economists (and merchants, and lawyers, and others) make decisions instead. Until biologists begin to replace economists because they have a superior ability to correct errors and to predict events (which should not be too difficult) there is not much hope for realistic decisions in human affairs.
If life is indeed Earth’s most important attribute, biology is then the discipline best able to guide man’s decisions concerning his (and Earth’s) welfare. If this is even partly so, we need a biology not Just active in knowing more of less and less, but also at knowing more of less plus less. Why? So that people may understand their world. And so that humanity may survive with dignity.
The Canadian Field-Naturalist — the Status Quo or a New Direction?
To some of us the most significant and lasting contribution that The Ottawa Field-Naturalists’ Club has made to society is the publication of The Canadian Field- Naturalist. From almost the very beginning, since 1880, the club has published a scientific journal and from the early years (1889 onwards) its scope has included papers on the natural history of Canada. This centennial year of the club is a time for contemplation, reflection, and, by the express wishes of Council, a reassessment of The Canadian Field-Naturalist’s réle as a publication of the club and its relationship to the club.
Do Problems Exist?
In general, the present members of the Council of The Ottawa Field-Naturalists’ Club are reported to be “uncomfortable” about The Canadian Field-Naturalist. Some would prefer more papers by amateur naturalists, more items of local interest, more club content, and less emphasis on professional scientific papers. Some, reflecting comments made by local members, question why a portion (40% in 1978) of their membership fees should be allotted to a publication that appears to have minimal relevance to the club and why those members who are not interested in The Canadian Field- Naturalist should receive it at all. Fortunately, others understand that The Canadian Field- Naturalist is providing a much needed service to Canadian natural history. Most people agree, however, that the club is the most appropriate publisher of The Canadian Field- Naturalist, at least until a more suitable alternative organization is evident.
There is no doubt that the relationship between The Canadian Field- Naturalist and The Ottawa Field-Naturalists’ Club as its publisher is a very important one. Unfortunately, however, uncertainty regarding this relationship continues to arise from time to time. Ina way the publication ofa national scientific journal by a basically local natural history club is an anomaly, especially as The Canadian Field- Naturalist is recognized as the “official” publication of the Ottawa club. It is the only publication specifically mentioned in the club’s constitution and is sent to all club members.
Until recent years many of the members of Council were senior scientists (the Ottawa area with many federal government departments has a high concentration of scientists) with strong interests in the journal. They recognized its broad scope and scientific significance. Today most Council members are not professional field-research scientists, hence the composition of Council is probably more comparable to those of other local natural history societies. Many of the professionals (mainly field-biologists) who were once active members of the club and served on its Council are now involved in different activities. Therefore, is it unexpected that some members of the present Council don’t really understand The Canadian Field- Naturalist? Their uneasiness about it is evident in their current re-evaluation of its rdle and in the stated view of the Chairman of the Publications Committee that the club should publish a journal that is in keeping with the wishes of the membership. But exactly what is meant by “membership”? Is it considered to be the “local” (arbitrarily defined geographically), largely non-professional members, the people who can most easily communicate their opinions to Council? Or does it also include, as it should in the true sense, the local and non-local professionals; the former local members who have moved away but still want to keep in touch with the club; the distant people who became members because they wanted to receive The Canadian Field-Naturalist (prior to 1976 this was the only way an individual could receive the journal); and possibly others who, although they may dwell far from Ottawa, wish for other reasons to belong to the club? And shouldn’t the opinions of our subscribers and other readers also be considered?
The members of Council are voted into office at the Annual Business Meeting. The slate drawn up by a Nominating Committee each year from the local members of the club has always been acclaimed into office by the local members who attend. To my knowledge there has not been a single club election in recent decades. Considering that the club’s Council is assumed to represent the
10
1979 SMITH: EDITORIAL Ui
membership, one can interpret the “wishes of the membership” to be equivalent to the wishes of the Council members after they have taken into account the expressed opinions of local members. In forming his/her opinion will each member of Council think of his/her own personal preferences or will he/she consider the broader outlook, recognizing The Canadian Field-Naturalist’s role in the advancement of scientific knowledge of Canadian natural history? And is recognition being given to all those the journal now serves beyond the interested local members, namely the subscribers, external members, authors, and the many readers who consult it in libraries?
The major reasons for my editorial then are: first, to alert those concerned about and interested in The Canadian Field- Naturalist to be informed of the present uneasiness of the Council and the steps it is planning to take; second, to solicit informed input from our readers to help the Council decide whether the status quo should be maintained or The Canadian Field- Naturalist should take a new direction; and third, to state my personal opinion regarding the journal’s present status and réle and my thoughts regarding its future.
Functions of The Canadian Field-Naturalist
To me The Canadian Field- Naturalist fills the important need fora national field-oriented natural history journal publishing, and hence recording for posterity, original and significant information with relevance to Canadian plants and animals. For some years now there has been a drop-off in club activity in geology and palaeontology and there has been a concomitant dearth of manuscripts submitted to The Canadian Field- Naturalist on these subjects. This is unfortunate because these areas of natural history were once very strong ones in the club and the journal. Thus The Canadian Field- Naturalist currently plays a role in advancing knowledge in the biological sciences as authors record, analyze, and interpret their data. In recent years this function has become more important because several journals formerly available to field-biologists will no longer accommodate purely observational (non-experimental) data nor descriptive passages outlining the results of field investigations. The Canadian Field- Naturalist, by acting as a model for content and format, also serves to stimulate amateurs and young biologists to record their observations and to start their own investigations leading to fruitful lifetime hobbies or careers as field-biologists.
There is no doubt for many of us that the scientific quality of The Canadian Field- Naturalist is currently high. Otherwise it would not attract submissions from a wide variety of natural scientists, nor would respected scientific experts serve as Associate Editors or referees, nor would the National Research Council of Canada have supported its publication by awarding substantial grants when funds were needed. In earlier years, however, The Canadian Field- Naturalist was neither completely rejected nor completely accepted by the scientific community because it did not use the peer review system and was only partially scientific. Today it is accepted as a scientific journal and is widely distributed, reaching many lay and professional readers including those in Canadian and foreign: libraries. It serves to varying degrees both writers and readers by permanently preserving valuable information of national importance and by helping to build the reputation of professionals who must publish in a refereed journal of high standards and quality.
Although from time to time The Canadian Field- Naturalist publishes significant scientific papers concerning Ottawa biota, I agree that in general it currently does not relate very much to local naturalists with purely local interests other than in its publication of the reports and notices of the club. Current editorial policy does exclude papers that are of only regional or local interest, i.e., those that are not nationally significant, but these papers are appropriate for and can be accommodated in society newsletters and in regional or local natural history publications, many of which are of excellent quality. If The Canadian Field- Naturalist were to publish these items, it would again be ina gray area and eventually it would lose its current status and reputation as a primary scientific publication.
I feel that most naturalists should find something of interest in every issue of The Canadian Field- Naturalist although I recognize that it does not fill the needs of all the local members. But the club does publish five times a year an excellent magazine, 7rail & Landscape, containing items of local
| THE CANADIAN FIELD-NATURALIST Vol. 93
natural history interest, matters of conservation in the Ottawa area, plus announcements of lectures, excursions, and special meetings of the club. As far as many local members are concerned Trail & Landscape in fact is the voice of their club, yet it has no official status as a club publication and its continued existence is not completely assured. Certainly re-evaluation of Trail & Landscape’s status, réle, and relationship with the club seems urgently required in the present context.
Clearly The Canadian Field-Naturalist is filling the need for a field-oriented national natural history journal; it serves both amateur and professional naturalists and field-biologists, maintains high scientific standing, and has assured itself of a place in history as it records the current state of the discipline. In doing so it is also fulfilling the second objective of the club, “to encourage investigation and publish the results of research in all fields of natural history and to diffuse information on these fields as widely as possible.”
Are Amateur Naturalists Considered?
One of the serious concerns of the Council of The Ottawa Field-Naturalist Club is the position of amateurs vis-a-vis The Canadian Field-Naturalist. Various members have recently expressed particular concern that the highly professional nature of the content and the more prestigious format of the journal have intimidated amateur naturalists and thus prevented them from submitting manuscripts. At Council’s request a survey was conducted of two volumes from each of the last three decades and all authors were classified as “professionals” if they had an institutional address and as “amateurs” if they had a home address. The survey clearly indicated a gradual decade-to-decade decrease in the number of papers by authors classed as amateurs. But these results are open to several interpretations. The question of whether the number of submissions from amateurs with data worthy of publication has decreased because of the journal’s content and format cannot yet be answered. I sincerely hope, however, that no potential author has been deterred from submitting a paper that he or she felt was of national significance.
Let us consider some possible factors that could have contributed to the results obtained in the survey.
a) Is an institutional address an adequate criterion for identifying an author as a professional? It must be realized that a professional in one field of science may be an amateur in another discipline even within the biological sciences. Also many authors prefer to use an institutional address even if the paper they submit has no relevance to their particular profession. Thus the survey could not identify all the amateurs in the true sense of the word.
b) Are the amateurs of today sending their manuscripts to other publications that were either not in existence or not of sufficient interest or quality for amateurs of earlier years? In general, over the last few decades most scientific publications, including The Canadian Field- Naturalist, have changed to become less anecdotal, more structured, and more polished. At the same time there has been a dramatic increase in the number and quality of alternative sources of publication for natural history notes. Some of the regional and local publications of natural history societies have changed from mimeographed newsletters, where often virtually any material submitted was accepted, to a printed booklet format, where raised standards are evident. The high calibre of these publications has enhanced the image of the organizations publishing them and surely is appreciated by their members. Trail & Landscape is an excellent example.
c) Isamateur science recognized as the initial training ground for many of those who will eventually make their living as professional field-biologists? Perhaps these young people with their special enthusiasm for natural history are our most inspired amateurs. Although many manuscripts submitted to The Canadian Field- Naturalist are from authors with institutional addresses, often the authors are really students, 1.e., advanced amateurs who are not yet professionals.
d) Are today’s amateurs motivated to make their own observations systematically and rigorously and to write them up for publication? In the past this motivation was often supplied by interested
1979 SMITH: EDITORIAL 13
professionals who spent considerable time answering questions, identifying organisms, and interpreting often routine natural phenomena for members of the public, including amateur naturalists. Amongst these were occasionally people with exceptional latent talent who needed only a bit of interest to be shown in them by such notables as Jim Baillie and A. F. Coventry in Toronto, Clifford Carl in Victoria, Earl Godfrey in Ottawa, and many others. Although these exceptional professionals published valuable papers on their own research, perhaps equally important although often unsung contributions on their part were in providing encouragement to beginning naturalists to observe and record significant data. Because of our increasingly complex society, and the drives to establish their own reputations and empires, it is my impression that fewer and fewer professionals in universities, museums, and government departments take time to communicate with amateurs. Therefore, often amateurs now cannot readily discern whether their observations, sometimes just important single observations, are of particular interest and significance. Moreover, the incentive for amateurs to report (write up for publication) their observations may be lacking without this professional encouragement.
é€) Dosome of the few particularly keen amateurs who want to help advance knowledge prefer to work under the direction of a professional field-biologist rather than on their own? Certainly Opportunities to do this are available and advertisements specifically outlining projects are fairly widely circulated. Undoubtedly any publications resulting from this type of joint amateur- professional collaboration bear an institutional address.
Jf) Overall, do more amateurs today pursue natural history for the particular pleasures it brings to them rather than through a desire to carry out a particular study or to contribute to knowledge? With the increased leisure time in our changing society as well as increased incomes, people are travelling more extensively, not only in Canada but all over the world. They enjoy adding new species to their life lists, and taking photographs and making sound recordings using the array of technical equipment now available to them. The greatly increased mobility and opportunities for fleeting but exciting glimpses of different biomes present a far different situation than in earlier years. Then people used to be more sedentary and amateurs were more interested and persistent in devoting time to the valuable study of a single species or a few local species. Their repeated, often tedious, observations over long periods of time provided data that could be synthesized and interpreted. New trends and even definite changes were uncovered. Of course, with the advancement of knowledge, it is no longer so easy to find new fields to conquer, e.g., to describe species or habits or extensions of ranges. Are many of today’s amateurs still willing to do potentially valuable long-term studies in the field and to analyze and interpret their data? Or are they preoccupied with spotting rare species here or travelling to distant lands to identify, check off, then move on to the next, rather than studying,
watching, and recording?
g) Are amateurs reluctant to send a manuscript to The Canadian Field- Naturalist because it is too “scientific”? Those of us currently responsible for the content of the journal are anxious to have submitted by amateur and professional naturalists and field-biologists papers on results of sound original investigations in any field of natural history that is of significance and relevance to Canada. The pages of the journal are open to all amateurs whose papers meet these criteria. Reluctant amateurs should be particularly aware that important data not put on record may be lost to science. Although we endeavor to maintain the journal as a first-class scientific one, we also emphasize that scientific writing does not need to be, and preferably is not, pretentious but rather is simple and straightforward. Ideally it should be clear, concise, accurate, logical, and interesting. The journal isa broad general one and it is important that the papers we publish be understood by as many as possible of our readers. Although we expect trained biologists to write their manuscripts in the accepted style (and not all do), I emphasize here that we are particularly willing to help amateurs by giving advice and guidance on writing to improve their submitted manuscripts. The major criterion for acceptance is the importance of the information and its relevance to Canadian natural history.
14 THE CANADIAN FIELD-NATURALIST Vol. 93
In the past, amateurs played an extremely important réle in the advancement of knowledge in the natural sciences, particularly in field biology. Are amateurs still doing so? My questions and possible interpretations of the results of the survey regarding amateurs may help to illustrate that answers to seemingly simple questions are often complex and involve many interrelationships.
Future Role of The Canadian Field-Naturalist
The existence of The Canadian Field-Naturalist as a primary scientific and hence archival publication depends on several factors. These include the submission of manuscripts that, after review by competent referees, are found acceptable for publication; the availability of sufficient funds to cover publication and distribution costs; and the agreement of the publisher to maintain the journal as such.
The Articles and Notes published in The Canadian Field-Naturalist are refereed and almost all undergo minor or major revision before they are accepted. But there are also several non-refereed pages in each issue containing general information considered to be of wide interest. Should the number of these pages be increased? Should they contain more items of interest only to the local club members? For instance, would items that now appear in Trail & Landscape (sent to all local members and any other members who request it) or in The Shrike (the club birding newsletter, available only on subscription) be suitable? If so, would these other publications still be maintained as they are now?
At present the major expenses of the journal are met by page charges levied to authors and the subscription fees from institutions. Individual subscribers number just over 300 but their fees plus the portion allotted from the membership fees are not insignificant. The results of a questionnaire circulated to the club’s membership with the renewal forms for 1974 (see editorial in Volume 89(1), 1975) indicated that most people were members in order to receive The Canadian Field- Naturalist, but at that time only institutions, not individuals, could subscribe. Those who were club members in 1975 were given a choice starting in 1976 of maintaining their membership in the club witha portion of their membership fees (currently 40%) going to the journal, or of becoming subscribers for exactly the same annual fee but with the entire fee (100%) going to the journal. I wonder how many through knowledgeable choice, apathy, reluctance to change the status quo, or perhaps lack of knowledge of the financial implications to the journal, chose to remain members of the club. The opportunity fora member to become a subscriber was offered only once although there is no reason anyone wishing to do so shouldn’t change from being a member to become a subscriber at the start of any year.
Because the club does have members across Canada and elsewhere, whether in name only or not, it considers that it speaks for a national and international membership. Although all members potentially have votes at the Annual Business Meeting and can elect the Council and introduce new business at the meeting, it is the local members, now mostly non-professionals, who come to the meeting, vote, and serve on the Council. But these are the people who will control the future of The Canadian Field- Naturalist.
The Council of The Ottawa Field-Naturalists’ Club intends to produce within a year or soa statement regarding the desired réles for all the club’s publications and their relationship to the club. Thus the specific positions of Trail & Landscape and The Shrike as well that of The Canadian Field- Naturalist will be clarified and the réle of each as a club publication defined. Because this is a complex matter, the Council executive has assured me that any changes in direction will be implemented slowly. Therefore, after reading the background material in this editorial, but not being constrained by it to matters covered therein if there are other points to be brought out, interested persons are invited to state their views. I hope that favorable as well as critical comments, if justified, will be made because it is important to reaffirm where the journal is performing satisfactorily as well as where it may need modifying. Subscribers have one way to influence the journal directly, and that is by maintaining or discontinuing their subscriptions, but they can also express their views regarding The Canadian Field Naturalist’s role as a publication of The Ottawa Field Naturalists’ Club. I hope
1979 SMITH: EDITORIAL 15
all interested readers will put forth their thoughts because there is still time to have input into the deliberations of Council on this matter. Indeed, I invite them to do so by writing directly to the club (Box 3264, Station C, Ottawa, Ontario K1Y 4J5); carbon copies to the Editor would be appreciated. More formal comments as Letters to the Editor for publication are also solicited.
The 100-year history of the club and the journal is perhaps unique and it is desirable that the two maintain a good relationship. Although the Editor and the editorial board are currently responsible for the editorial policy and content of the journal, ultimately it is the Council’s decision that will shape the future of The Canadian Field-Naturalist.
This editorial is a distillation of many hours of discussion and analysis of the past and the current situation as interpreted by my husband and me. Therefore, by expressing our concerns, I hope that the opinions solicited from readers of all categories will help to influence the outcome of the current re-evaluation of the rdle of this journal. Furthermore, I hope the Council’s written statement will solve the misunderstandings and misinterpretations, calm the Council’s current uneasiness, clarify the club’s policy about its publications, and strengthen the position of The Canadian Field- Naturalist by formal reaffirmation of its present rdle as a primary scientific natural history publication published in Canada and relevant to Canada.
LORRAINE C. SMITH Editor
Demographic and Dietary Responses of Red-tailed Hawks during a Snowshoe Hare Fluctuation
ROBERT S. ADAMCIK,! ARLEN W. TODD,? and LLOYD B. KEITH!
'Department of Wildlife Ecology, University of Wisconsin, Madison, Wisconsin 53706 2Department of Recreation, Parks and Wildlife, Edmonton, Alberta
Adamcik, Robert S., Arlen W. Todd, and Lloyd B. Keith. 1979. Demographic and dietary responses of Red-tailed Hawks during a Snowshoe Hare fluctuation. Canadian Field-Naturalist 93(1): 16-27.
Red-tailed Hawks (Buteo jamaicensis) responded functionally but not numerically to a cyclic fluctuation of Snowshoe Hares (Lepus americanus) near Rochester, Alberta. During 1966-1975, 89% of the resident pairs laid eggs, a nesting density of | pair per 8.3 km?. Mean clutch size (overall 2.2) ranged between years from 1.7 to 2.6, partly in response to prey-density changes. Mean hatching dates varied from 30 May to 10 June. Marked differences in annual productivity, 0.28 to 1.90 fledged young per breeding pair, primarily reflected nestling mortality. About 50% of all nestling losses were associated with food shortage. Seventy percent of annual variation in mortality through age 4 wk was jointly attributable to the frequency of rain and the weight of food brought to nestlings. The latter varied directly with Snowshoe Hare densities. The stationary population of breeding adult redtails contrasted with the numerically and reproductively cyclic horned owls (Bubo virginianus), but resembled redtail and other temperate-zone raptor populations further south. Food reductions during hare declines in the boreal forest ecosystem do not seem to be critical to survival of redtail nestlings unless combined with above-average rainfall.
Key Words: Red-tailed Hawk, Buteo jamaicensis, Snowshoe Hare, Lepus americanus, population dynamics, cyclic
fluctuations.
A study of Red-tailed Hawks (Buteo jamai- censis) was conducted in central Alberta during 1966-1975. Its objective was to examine changes in raptor demography, food habits, and pred- atory-prey interactions during one complete population cycle of the Snowshoe Hare (Lepus americanus). Early results of this work were reported by Meslow and Keith (1966) and Luttich et al. (1970, 1971). McInvaille and Keith (1974) summarized findings through 1971, the year of peak spring densities of hares on the study area; they examined intraspecific relation- ships among redtails and interspecific relation- ships between redtails and Great Horned Owls (Bubo virginianus). They also assessed the effect of increasing hare densities on redtail breeding biology, and estimated rates of predation on prey populations. The most recent paper, that of Keith et al. (1977), examined the role of Red- tailed Hawks and other predators in the cyclic fluctuations of Snowshoe Hares and Ruffed Grouse (Bonasa umbellus).
The hare population at Rochester declined after spring 1971, reaching the lowest point in its cycle by spring 1975. Over those 4 yr, significant changes occurred in reproduction, nestling sur- vival, and food habits of redtails. This paper
describes such changes and examines their relationship to prey densities. It also presents a general analysis of redtail productivity since 1966.
Methods Study Area
The 162-km? study area (130 km?in 1966) was a block of mixed agricultural and forested land near Rochester, Alberta, about 100 km N of Edmonton. Luttich et al. (1971) and Rusch etal. (1972) described the vegetation, topography, and land-use practices on the area; McInvaille and Keith (1974) classified the major habitats and outlined their distribution as of 1971. Except for secondary growth in fire-killed areas, and some further clearing of forested land for pasture, the study area changed little over the next 4 yr.
The breeding season for redtails in central Alberta is early April through July. Mean temperature at Rochester during this period is 12°C, with average minimum and maximum temperatures of 6°C and 18°C, respectively. Temperatures near freezing have been recorded in all summer months; and during extended periods of cloudy or rainy weather in July and
1979 ADAMCIK ET AL.: RED-TAILED HAWKS AND SNOWSHOE HARES 17 TABLE !—Summary of weather data during 10 breeding seasons of the Red-tailed Hawk near Rochester, Alberta! Periods in nesting cycle and types of weather data 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 Mean Courtship Days in period? 26 31 31 Ds 23 DY 36 31 22 24 28 Mean daily temperature (°C) -l 2 4 9 5 5 2 3 6 5 4 Days with precipitation (%) 31 19 29 52 9 15 3] 29 32 46 29 Mean daily precipitation (mm) het Ost Ox WA Oa 0.8 AO Oss 1.1 O09) Mean snow depth (cm) 7 25 | 2 9 25 24 6 23 8 13 Days with snow on ground (%) 65 97 29 40 52 78 83 58 82 46 63 Incubation Days in period 32 32 32 32 32 sy) 32 32 32 32 32 Mean daily temperature (°C) 12 12 10 11 10 13 12 1] 9 11 1] Days with precipitation (%) 44 25 34 34 22 22 DD) 38 50 53 34 Mean daily precipitation (mm) 2.1 1.2 0.8 Ie 0.4 1.0 0.9 2.1 0.7 ES) 1.2 Nestling (pre-tethering) Days in period 28 28 23 28 26 30 28 34 24 27 28 Mean daily temperature (°C) 13 14 14 14 17 13 14 15 15 13 14 Days with precipitation (%) 39 43 57 32 39 57 50 53 42 70 48 Mean daily precipitation (mm) 1.1 0.9 1.9 ha eal 4.2 SHO AN (0) O) eles 2.6 Tethering Days in period 20 28 27 22 28 21 23 16 31 22 2 Mean daily temperature (°C) 17 18 16 16 16 15 13 15 15 19 16 Days with precipitation (%) 60 43 67 55 64 67 61 69 74 55 62 Mean daily precipitation (mm) a) WHO Se) 4.2 6.7 5.0 IES 16 4.8 305) 3,5)
'Weather data were collected at the Meanook Meteorological Observatory, 26 km N of Rochester. Total days in each period were determined as follows: courtship—date of first observation of a red-tail on the study area to mean date of start of incubation; incuoation—mean date of start of incubation to mean date of hatch (32 d); nestling—mean date of hatch to mean date of tethering:
tethering—mean date of tethering to mean date of release.
August, daytime maximums around 7°C are not uncommon. Although occasional snow flurries occur as late as mid-May, most preci- pitation from late April to August falls as rain. Total spring-summer (15 August — 31 August) rainfall is variable, ranging from 11 to 44cm during our study. Heavy showers and rainstorms are common, but precipitation more often occurs as light rain over several days.
Demographic Methods
Methods of censusing raptors, tethering nest- lings, and estimating prey densities were iden- tical to those described by McInvaille and Keith (1974). Snowshoe Hare and Ruffed Grouse population estimates were revised slightly after additional analyses. We expanded the small- mammal census to include a spring (April-May) index for 1973-1975, and determined summer (June-July) densities of juvenile Richardson’s Ground Squirrels (Spermophilus richardsonii) on two study areas beginning in 1969. Waterfowl data used in the present paper were based on counts along a 0.4-km-wide aerial transect
between the towns of Cold Lake and Swan Hills. This transect passed about 11 km N of Roches- ter. Weather data were collected at the Meanook Meteorological Observatory, 26km N _ of Rochester.
Examination of Weather Data
To analyze relationships between weather and productivity of redtails, we arbitrarily divided their reproductive cycle at Rochester into four stages: courtship, incubation, nestling (pre- tethering), and tethering (Table 1). The court- ship stage began with the first date of observa- tion on the study area each spring. The tethering stage ended with release of the last young we had tethered to obtain food data. Mean dates of first observation, start of incubation, hatch, tethering of nestlings, and release of fledged young during 1966-75 were 5 April, 3 May, 4 June, 2 July, and 25 July, respectively.
Within the courtship stage we examined five weather variables: mean daily temperature, percent days with precipitation, mean daily precipitation, mean snow depth, and percent
18 THE CANADIAN FIELD-NATURALIST
days with snow on the ground. The last two variables were irrelevant in the three later stages of the reproductive cycle.
Results Prey Populations
Spring densities of adult Snowshoe Hares peaked in 1971 at 510 per 100 ha of habitat, and thereafter declined to only 1% of peak numbers by 1975 (Table 2). Because the birth rate was higher in 1970 than in 1971, young hares were more numerous in 1970, and the total spring- summer (May-July) population was conse- quently higher that year. As with adults, total hare numbers fell markedly after 1971 to about 1% of peak numbers by 1975.
Richardson’s Ground Squirrel populations rose between 1968 and 1970, fell to about 25% of their maximum by 1974, and increased again in 1975. During the highest year, adult densities averaged 988 per 100 ha of habitat (closely grazed pastures) in May, and juveniles averaged 3350 per 100 ha in June (Table 2).
Populations of voles (Microtus pennsylvan- icus) continued to fluctuate during 1971-1975, as in previous years. amplitudes of change between high and low populations were 7- to 32- fold in late summer trap-night indices. Lowest numbers occurred in August 1968, 1971, and 1975. May populations were lower in 1973 and 1975 than in 1974 (Table 2).
Ruffed Grouse were most abundant at 61 per 100 ha of upland forest in May 1968. A major decline took place between the springs of 1970 and 1972, as numbers fell 65% to 16 per 100 ha. The population remained low through 1974, then more than doubled by May 1975.
Sharp-tailed Grouse (Pedioecetes phasian- ellus) increased from 1966 to 1970, but decreased abruptly within the next year and were scarce thereafter (Table 2). Waterfowl trend data for 1971-1975 indicated a general decline of about 50%.
Red-tailed Hawk Numbers, Reproduction, and Nestling Mortality
During 1972-1975, the Red-tailed Hawk population on our study area maintained the approximate numerical stability of earlier years (Table 3). Total individuals varied from 53 in 1967 to 39 in 1975, while breeding pairs ranged
Vol. 93
from 24 (1 per 6.8 km2) in 1966 to 16 (1 per 10.1 km2) in 1973. There was no significant difference between years in portion of the population paired (mean 94%), the proportion breeding (mean 84%), or the proportion of pairs breeding (mean 89%).
Mean hatching dates differed significantly (P <0.05) between years (Figure 1), being latest in 1967 (10 June) and earliest and most variable in 1972 and 1973 (2 June and 30 May, respectively).
Significant (P < 0.05) annual variation also occurred in mean clutch size and mean brood size during 1966-1975. Mean clutch sizes were largest in 1970 and 1972 (2.6) and smallest in 1966 (1.7) and 1975 (1.9). Egg counts were made only once per nest, ranged over the incubation period, and included nests off the study area (Table 3, footnote 2).
There was a marked change in the causes and rates of nestling mortality among redtails during 1972-1975 compared with earlier years (Table 3). Losses attributable largely to horned owls averaged 43% in 1968-1969 (Luttich et al. 1971), but dropped to 14% in 1970-1971, as sharply rising hare densities apparently buffered such predation (McInvaille and Keith 1974). Preda- tion by owls recurred in 1972 coincident with a major decline in hares. During 1973-1975, we recorded no horned owl predation on nestling redtails, as Snowshoe Hares became scarce and owl numbers declined through egress and non- breeding (Adamcik et al. 1978). But total nestling mortality on the study area rose from 37% in 1972 to a mean of 66% during 1973-1975. Almost all of such losses occurred before tethering (i.e., with 3-4 wk after hatching) in 1973-1975, whereas only about half had occur- red by that time in earlier years.
Of the 30 young lost prior to tethering during 1966-1972, 18 disappeared completely, and the remains of 12 (40%) were found in or below the nest. Four of the latter had been cannibalized by siblings.
In 1973, 8 of 18 (44%) dead young were found in or below the nest, and 6 of these had been cannibalized. In 1974, 4 of 14 dead young starved in the nest, 2 disappeared, | was cannibalized, and 7 (50%) died after falling from the nest. Three of the latter seven birds survived their initial fall and were replaced in the nest; two
19
ADAMCIK ET AL.. RED-TAILED HAWKS AND SNOWSHOE HARES
1979
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20 THE CANADIAN FIELD-NATURALIST
Vol. 93
TABLE 3—Some population and productivity statistics for a Red-tailed Hawk population on a 162-km? study area near
Rochester, Alberta
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
Population statistics
Breeding pairs! 24 20 19 18 19 19 21 16 17 18
Non-breeding pairs ? 3 3 3 2 | 2 4 2 1
Resident singles ? 7 4 0 | 2 2 4 2 1 Productivity statistics?
Mean clutch size NWS 2.00 AMT 2.14 2.56 2.28 2.61 2.00 2.42 1.9
Mean brood size 1.71 2.00 2.07 2.14 yen y) DEG D3) 1.96 2.26 1.71 Nestling mortality (%)3
0-4 weeks 0 12 24(10) 11 5 11(16) 29(18) 64(45) 45(23) 72(78)
5-8 weeks 5 0 33(27) 28 13 0(38) 12( 6) 0(46) 17(22) 25(40)
Total 5 12 49(35) 36 17 11(48) 37(23) 64(70) 54(40) 79(87) Young fledged per
breeding pair4 1.58 1.60 0.68 1.22 1.90 37) 1.29 0.63 0.94 0.28
‘Breeding pairs laid eggs; nonbreeding pairs did not.
?Mean clutch and brood sizes include nests off the 162-km2 study area, but within 40 km. There were 4, 1, 24, 10, 15,8, 15, and 16 off-study-area clutches in 1966-1968 and 1971-1975, respectively; and 5, 5, 18,9, 23, 10, 14, and 13 broods. Total nestling mortality (%) equals 100 times the complement of the product of the two-interval survival rates: thus for 1969 total mortality was 100 [1 — (0.89) (0.72)] = 36.
’Mortality rates shown in parentheses are for 18, 11, 24, 11, 13, and 13 off-study-area broods in 1968 and 1971-1975, respectively.
4Includes nests off the 162-km2 study area.
fell out again, and the third was cannibalized by a sibling which later starved. In 1975, 15 of 18 (83%) dead nestlings died during a single 32-h period of heavy rain, high wind, and low temperatures. In an earlier year, 1972, 8 of 12 deaths had occurred within | wk of a heavy rainstorm. The immediate causes of death were thus notably different between years.
We determined pre-tethering losses among nestlings in nests situated off the study area during 6 of 10 yr (Table 3). In no single year did such losses on and off the study area differ significantly, but the overall averages of 44 and 32%, respectively, were different (P< 0.05). We suspect that our more frequent intrusions ad- versely affected brooding and feeding of young at study area nests. On the other hand, as discussed in a later section, mortality during the tethering period (age 5 to 8 wk) on the study area averaged significantly less (P <0.05) than untethered young elsewhere (1.e., 15 vs. 30%). The end result of these time- and area-specific differences in mortality was a similar mean rate of loss over the entire nestling period of about 50% on both areas
Dietary Responses to Changing Hare Densities
Food Habits
Snowshoe Hares, Richarson’s Ground
Squirrels, and waterfowl constituted between 59 and 89% of the weight of food for young Red- tailed Hawks at Rochester each year (Table 4). The remainder consisted of a variety of small-to medium-sized mammals and birds, of which Franklin’s Ground Squirrels (Spermophilus
franklinii), voles and sometimes grouse were
important.
Snowshoe Hares were the dominant food of redtails during 1970-1973. Their peak use in 1970-1971 reflected the hawks’ strong func- tional response to increasing hare densities (MclInvaille and Keith 1974). During the next two years hare densities declined sharply, but there was a notable lag in the redtails’ functional response to declining hare numbers. The con- comitantly low ground squirrel population (Table 2) may have been partly responsible for this lag. By 1974, however, hares were near their cyclic low, and ground squirrel densities were the lowest we recorded; redtails then switched to waterfowl, which became the most important single food item, comprising 36% of their diet
Consumption of Richardson’s Ground Squirrels was lowest (10% biomass) during 1972, coincident with continued heavy utilization of hares and a sharp decline in the ground squirrel population (Tables 2 and 4). By 1975, with hare densities at their cyclic low and ground squirrel
1979
ADAMCIK ET AL.: RED-TAILED HAWKS AND SNOWSHOE HARES 2)
20 MAY
25 3
©090000096
JUNE
20
10 IS
FiGure 1. Annual distribution of Red-tailed Hawk hatching dates on the 162-km? study area near Rochester, Alberta. Dates of hatch of 63 to 84% (mean 72%) of study-area nests were determined yearly. Circles indicate nests first visited during incubation and/or within | wk after hatching. Mean date is given at left.
densities up four-fold, ground squirrels comprised 40% of the redtails’ diet.
Biomass of Prey Brought to Tethered Young
The amount of food supplied to tethered nestlings varied significantly (P < 0.01) between years (Table 5). During 1966-1971, the mean daily biomass of prey per brood rose steadily from 345 to 768 g, while that per individual young increased more irregularly from 212 to 444 g owing to annual differences in brood size. Between 1971 and 1973, the amount brought
daily to broods and individual young declined by 66 and 48% to means of 260 and 231 g, respectively, and remained low through 1975. Eighty-nine and 86% of the foregoing annual variation for broods and individual young, respectively, was attributable to changes in mean daily biomass of Snowshoe Hares in the redtail diet.
Annual utilization of hares was a direct function of their densities: regressions of mean daily biomass on total hare population estimates (Table 2) yielded coefficients of determination
2D THE CANADIAN FIELD-NATURALIST Vol. 93
TABLE 4 — Spring-summer (1 June - 31 July) food habits of nestling Red-tailed Hawks near Rochester, Alberta!
Percent frequency Percent biomass
Prey species? 66) "67" 68 69 70) Jl 72 #73 74 75 66° 67 68 69-70) S/5 SZ See eS
Snowshoe Hare 2 4 7 6 4a Bh — 2 9 tr 0 8 S17 24") 25 46 2a eaesS 4 0 Richard’s
Ground
Squirrel Ai 3 DS DR BP) 2109 6G Ul 7 V4 42) 25 34 939) 38° 28) sO Sees, Franklin’s
Ground
Squirrel 4 5 6 Al {ivr 3 3 2 2 2 5 7 7/ 5 l 3 5 4 Volesand mice 32 41 13 34 #40 30° 36 42 44 #23 5 6 DD 5 4 y) 4 6 10 4 Other mammals 7 10 16 13 I 5) 6 7 G@ DW 6 8 8 9 | 5 4 5
Total
mammals 6 2 6/7 7 87 8 6) Wl SO. 6 G © 7 9 8) 90 GG 77 54 74
Waterfowl 8 12 Wl Gemedte eo alOh BR eae ae 27a, alle Bel 5 1 205 Wee SOmen9 Ruffed Grouse 2 | Ore a 2 | l | tir One | SA ats) I Phar), am Ot 0 Sharp-tailed Grouse l | | | I itr OR OR OY 2a De ne? | | ltr Or O- @ Unidentified Grouse I I 0 I 0 eet OR Om OL reed 822 SO) 2a er Omer) | O-= Oo Other birds 3 12 IS 10 © FT IG IS Io Bl IW »d Tile at RD! gD ee eo NO Total birds 25m Di Boer WIS) 3675 29" 405535) 850372 25- <2) NN cls WS le ae Ome Totals4 101 100 100 100 100 100 99 100 99 99 101 100 100 100 101 101 99 101 101 101
'Total number of food items was 695, 1063, 585, 563, 879, 545, 1224, 387, 811, and 299 in 1966-1975; biomass total (in kilograms) was 167.2, 255.0, 199.9, 161.6, 298.9, 215.6, 308.0, 85.8, 107.5, and 47.6, respectively.
*Prey not specifically identified in the table were “Voles and mice”: Microtus pennsylvanicus (average > 80% of small-mammal biomass). Clethrionomys gapperi (7%), Peromyscus maniculatus (4%), Zapus hudsonius (1%), and Sorez cinereus (tr): “Other Mammals”: Ondatra zibethicus, Tamiasciurus hudsonicus, Thomomys talpoides, Glaucomys sabrinus, Mustelafrenata, M. nivalis, M. erminea, Mephitis mephitis; “Waterfowl”: Podiceps grisegena, Anas platyrhynchos, A. acuta, A. strepera, A. discors, A. carolinensis, A. americana, A. clypeata, Aythya americana, A. collaris, A. affinis, Bucephala albeola, Porzana carolina, Fulica americana; and “Other birds”: Accipter cooperi, Falco sparverius, Perdix perdix, Charadrius vociferus, Columba livia, Colaptes auratus, Sphyrapicus varius, Picoides villosus, Perisoreus canadensis, Pica pica, Turdus migratorius, Sturnus vulgaris, Dendroica petechia, and unidentified songbirds and domestic chickens. 3Less than 0.5.
4Insects and amphibians constituted less than 1% of the total biomass in all years.
TABLE 5—Weight of prey items brought to tethered nestling Red-tailed Hawks near Rochester, Alberta!
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
Mean daily biomass (g)
of food per brood
Snowshoe Hare 28 Wi 121 122 289 399 229 101 14 0
Other prey species 317 375 383 457 340 369 280 159 331 316
Total (+ SE) 345 +30 452445 504+76 579+114 629+66 768 +80 5S09+53 260423 345+55 316+48 Mean daily biomass (g)
of food per individual
Snowshoe Hare 17 47 92 68 174 231 170 90 10 0
Other prey species 195 229 292 257 204 213 207 141 228 173
Total (+ SE) DIDS AN6 2762 30) S84ee al 325 22 Sl, S78 245) 7444 se 38) 3772 83" 23 sa DRS eee OMe laws 1The number of tethered broods was 14, 15, 13, 11, 17, 12, 17,7, 7, and 3 during 1966-1975, respectively. Prey biomass totals during 1966-1971 have been
recalculated since the study by McInvaille and Keith (1974), using better estimates of mean prey weights; trends remained the same as reported in that earlier paper.
1979
(r2) of 0.89 and 0.79 for broods and individuals.
The above relationships reflect both the hare’s periodic domination of the prey base, and the redtail’s strong functional response to fluc- tuating hare densities.
Nest Distribution
Using Clark and Evans’ (1954) _nearest- neighbor test (see McInvaille and Keith 1974), we tested for randomness the spacing within annual nesting populations during 1972-1975. As in previous years, the distribution of redtail pairs on the study area was significantly (P< 0.05) regular, suggesting that territoriality continued to function as a spacing mechanism.
General Analysis of Factors Affecting Productivity
The most notable demographic change among Red-tailed Hawks from 1966 to 1975 was the lower fledging rate during the last 3 yr: viz., 0.62 young per breeding pair in 1973-1975 vs. 1.38 in 1966-1972. Although the main immediate reason for this decline was increased nestling mortality (Table 3), there were significant annual variations in mean date of nest initiation, and mean clutch and brood size, which might also have affected productivity. We therefore examined each component of productivity to determine what affected it and whether it interacted importantly with others to influence rates of fledging.
We considered the following demographic variables: (1) mean date of nest initiation (= start of incubation); (2) mean clutch and brood size; (3) hatching success; (4) nestling mortality to age 3-4 wk (pre-tethering); and (5) nestling mortality from tethering to age 7-8 wk. Where appropriate, and where data were adequate, we examined each of the above in relation to weather; prey density and/or biomass brought to young; and frequency of observer visits to nest sites during courtship, incubation, nestling, and tethering periods.
Mean Date of Nest Initiation
Mean date of nest initiation was analyzed in relation to weather factors and prey population levels through simple and multiple regression. Annual variation in mean date of nest initiation was not significantly related to percent days with precipitation, average daily precipitation, average snow depth, percent days with snow on
ADAMCIK ET AL.: RED-TAILED HAWKS AND SNOWSHOE HARES 23
the ground, or mean daily temperature during the courtship period. Nor was there any significant relationship between annual dates of nest initiation and spring densities of Snowshoe Hares, Richardson’s Ground Squirrels, or previous-fall densities of mice and voles. Dates of nest initiation were likewise unrelated to various combinations of prey population indices and weather data.
Clutch and Brood Size, Hatching Success,
and Nest Desertion
We initially suspected that weather conditions during courtship affected availability of prey and/or redtail hunting activity, and thus might influence clutch size. Annual variations in mean clutch and brood sizes, however, were unrelated to weather at Rochester. Years with largest clutches (1970, 1972, and 1974) had a broad spectrum of weather conditions during the courtship period (Tables | and 3). For example, 1970 and 1972 had mean daily temperatures during courtship of 5° vs. 2°C, rain or snow on 9 vs. 31% of the days, and snow depths of 9 vs. 24cm. In 1966, when clutches were smallest, mean temperature and percent days with precipation resembled conditions in 1972, while snow depth was close to that in 1970. Additionally, we could find no correlation between clutch size and average daily precipi- tation or percent days with snow on the ground.
Although our data suggest that prey abundance may influence clutch size, the relationship was certainly not clear-cut. The large-clutch springs of 1970 (2.6) and 1974 (2.4) were each associated with high vole populations (MclInvaille and Keith 1974; Table 2); hare and > ground squirrel densities were also high in the first case but low in the second. In 1972, when clutches were equally large (2.6), adult hare densities were about 70% of those in 1970, adult ground squirrels about 30%, and voles were little utilized and probably scarce. The two springs in which mean clutch size was smallest, 1966 (1.7) and 1975 (1.9), were characterized by low hare and vole populations; we have no information on adult ground squirrels in 1966, but they too were low in 1975.
It is, of course, possible that conditions on winter ranges or during migration influence the size of redtail clutches. There was a positive and nearly significant correlation (r = 0.60, P = 0.07)
24 THE CANADIAN FIELD-NATURALIST
between annual dates of first arrival at Rochester and mean dates of egg laying, but mean clutch sizes were largely unrelated to the latter (r = -0.34, P > 0.25). The cause of major annual variations in mean clutch size probably resided on the breeding grounds since largest clutches occurred coincidently during 1970 and 1972 among redtails and non-migratory Great Horned Owls at Rochester (Adamcik et al. 1978).
In calculating rates of hatching and nest desertion prior to hatching, we excluded nest desertions attributable to climbing at the onset of laying or incubation. The significant between- year difference in hatching and desertion rates was entirely owing to data from 1968. In May, a major fire swept through part of the study area and likely prompted four nest desertions. Only 50% of all eggs hatched that year, and 6 of 19 (32%) active nests were abandoned prior to hatching. During the other nine years, hatching success averaged 92% (range 79 to 100%) and nest desertion only 6% (range 0 to 17%).
Pre-tethering Mortality
Pre-tethering losses of nestlings varied between years from 0 to 75% (Table 3). We analyzed such mortality through stepwise regression, in which the initial independent variables were mean daily temperature, percent days with precipitation, mean daily precipi- tation, mean numbers of days between our visits to nests, and mean prey biomass brought daily to tethered broods (expressed both as biomass per brood and per nestling). All statistics except the last were obtained during the pre-tethering period. The amount of food brought to young was measured during the tethering period, but we considered it also indicative of relative amounts provided before tethering. We chose a discriminant probability level of 10%, and constructed two separate models, one incor- porating mean daily biomass of prey per tethered brood, the other per individual.
The above described regression analysis discarded mean daily temperature, mean daily precipitation, and our frequency of visits during the nestling stage from those models which best accounted for the annual variance in _pre- tethering mortality. The resulting multiple regression equations and coefficients of determination were these:
Vol. 93
(1) Y; = 3.88 + 1.36A; — 0.14B; r = 0:67; FQ,7) = 7, Bs
(2) Y,; = 8.49 + 1.25A; - 0.09C, r =0.73; F2,7) =9:49, P1005
where Y; = estimate of pre-tethering mortality in year 1;
Ai; = percent days with precipitation
during the nestling stage in year 1;
B; = mean biomass (g) of prey brought
daily to individual tethered young in year 1;
C, = mean biomass (g) of prey brought
daily to tethered broods in year 1.
These models leave approximately 30% of the variance in early nestling mortality unaccounted for. We mentioned previously that Luttich et al. (1971) attributed higher tethering-period mortality in 1968 and 1969 to horned owl predation, and MclInvaille and Keith (1974) suggested that such predation was buffered by the rising hare population in 1970 and 1971. A further horned owl kill, the first since 1969, occurred in 1972, when hares had declined sharply and owls were still abundant. Owl numbers fell rapidly during 1973-1975 (Adam- cik et al. 1978), and no further predation on tethered redtails was observed. Losses to horned owls, either before or after tethering, would likely be independent of weather and biomass of prey brought to young redtails, and might thus account for some if not most of the remaining unexplained variance in our models.
Tethering-period Mortality
Variations in tethering-period mortality were irregular, and independent of weather factors, amount of food supplied by adults, or prey population densities. This contrast with pre- tethering mortality doubtless reflects an in- fluence of our tethering methods, as two important causes of pre-tethering mortality, sibling aggression and exposure, were largely prevented by tethering. Tethered nestlings could not reach one another; and beginning in 1971, tethering sites were kept dry with a suspended plastic sheet. Thus losses of study-area young were probably minimum estimates of normal tethering-period mortality. This conclusion is supported by the fact that in 2 of 6 yr tethering-period mortality was significantly
IDS)
lower (P< 0.05) on the study area than off (Table 3); and in at least 1 of the remaining years (1968), the main mortality factor was owl predation, which tethering did not prevent.
Discussion Comparative Demography
Reported densities of nesting redtails have ranged widely from | pair per 1.3 km? in California (Fitch et al. 1946) to | pair per 39.5 km? in Utah (Smith and Murphy 1973). The mean of | nesting pair per 8.3 km? at Rochester over 10 yr was near that of | pair per 11.3 km? reported in nine studies, including the above two, during 18 yr (Craighead and Craighead 1956; Gates 1972; Hagar 1957; Johnson 1975; Orians and Kuhlman 1956; Seidensticker and Reynolds 1971).
Eleven percent of 188 pairs at Rochester did not lay eggs during 9 yr, 1967-1975. This was close to the 14% of 278 pairs reported on six other study areas during 13 yr (Craighead and Craighead 1956; Hagar 1957; Johnson 1975; Orians and Kuhlman 1956; Smith and Murphy 1973). Such lack of nesting applied to adults, 1.e., birds almost 2 yr and older (Luttich et al. 1971), because in only two cases (Gates 1972; Luttich et al. 1971) were yearlings (brown-tailed indi- viduals) paired. Each of these yearlings had mated with an adult.
The annual frequency of resident singles varied from 0 to 13% of the total Red-tailed Hawk population at Rochester. When concerted efforts were made in earlier studies to obtain a total census, unmated birds were likewise often found, but in variable numbers (Craighead and Craighead 1956; Fitch et al. 1946; Smith and Murphy 1973). The percentage of yearlings among singles apparently differs markedly between areas: all singles were yearlings in southern Michigan (Craighead and Craighead 1956), whereas none was at Rochester. Fitch et al. (1946). described the harassment of single birds by territorial pairs on a California study area, and it seems likely that a major portion of the yearling cohort may frequent localities where adult breeding densities are low but food 1s plentiful.
Henny and Wight (1972) calculated that maintenance of redtail populations was depen- dent upon a fledging rate of about 1.35 young
ADAMCIK ET AL.: RED-TAILED HAWKS AND SNOWSHOE HARES D5)
per breeding pair. This calculation was based on the assumptions, among others, that the 22% nonbreeders reported in studies published through 1970 were yearlings, and that all adults nested. We have noted above that non-nesting occurs among adults, averaging 13% of 466 resident pairs. This is undoubtedly a con- servative estimate since unpaired adults are also frequently present. Yearlings are so rarely a part of the paired resident population that they can be largely ignored as potential breeders.
Reduction of adult nesting from 100 to 87% increases the estimated required fledging rate from about 1.35 to 1.56 young per breeding pair. These calculations are particularly sensitive to errors in age-specific estimates of annual mortality. As Luttich et al. (1971) pointed out, first-year mortality may have been overesti- mated, thereby elevating the rate of fledging apparently needed for population maintenance. The stationary redtail population at Rochester, for example, fledged a mean of 1.38 young per breeding pair during the first 7 yr of our study. Although we may not know precisely the fledging rate that will balance the population, the much lower rate that occurred during the last 3 yr (mean of 0.62) was doubtless inadequate. In the absence of compensatory changes in survival and/or ingress, the earliest that such decreased productivity might have been detected by us was in 1975; but our population data are really insensitive in this respect, because an ap- proximately 50% drop in fledging rate would theoretically reduce by only 2 the number of pairs present 2 yr later.
Henny and Wight’s (1972) survey of redtail clutch sizes implied east-west and south-north gradients of increase. Their mean of 2.9 for 20 nests in southern British Columbia, Alberta, and Saskatchewan was among the highest noted. Our data from Rochester do not fit this model. Annual means recorded by us ranged from 1.7 in 1966 to 2.6 in 1970 and 1972 (Table 3); and the overall average of 2.2 during 1966-1975 was comparable to the lowest regional means shown by Henny and Wight. Our egg counts, conducted only once during incubation and at no consistent stage, provided an estimate of mean clutch size over the incubation period; consequently, they may be biased low if partial losses or clutches occurred before hatching. We suspect, however,
26 THE CANADIAN FIELD-NATURALIST
that most earlier studies of redtails were similarly biased.
Factors Affecting Nestling Survival to Age 3-4 Weeks
Fluctuations in nestling mortality influenced annual productivity of redtails at Rochester more than did all other demographic variables. About 70% of the variance in pre-tethering mortality was jointly attributable to frequency of rainfall and amount of food provided by parent birds. These two factors are not likely independent, because redtail hunting activity, and probably hunting success, were reduced by rain. The amount of food brought to nestlings was, of course, also affected by prey densities.
Direct adverse effects of rain on survival of nestling redtails was earlier observed in California (Fitch et al. 1946) and New York (Hagar 1957), but not among Red-shouldered Hawks (Buteo lineatus) in Maryland (Henny et al. 1973) or Buzzards (Buteo buteo) in England (Tubbs 1974). Several times at Rochester entire broods were found dead, wet, and abandoned after heavy rains.
Although it was not always possible to isolate the individual roles of inclement weather and low prey densities in nestling mortality, we could at least identify situations where malnutrition rather than exposure per se appeared mainly responsible. We conclude that emaciation, cannibalism, and most falls from nests were largely symptomatic of food shortage. An unknown but substantial portion of total disappearances was probably also caused by cannibalism and falls, and thus likewise ascribable to food shortage. From the above, we estimate that approximately 50% of pre- tethering losses resulted directly or indirectly from a shortage of food.
Reproductive Strategy of Northern Redtails Luttich et al. (1971) noted that breeding populations of arctic- and temperate-zone rap- tors responded differently to changes in prey densities. The former, largely dependent on widely fluctuating microtines, are highly mobile and annually concentrate in areas where lemmings and voles have attained temporary abundance. Temperate-zone raptors, on the other hand, exploit a much more diverse and stable prey base, and local breeding populations of these
Vol. 93
raptors are often remarkably stationary from year to year (see recent summary by Newton 1976, p. 280). Newton (1976) concluded that, where nest sites are not limiting, regional differences in breeding densities of diurnal raptors reflect differences in average levels of prey abundance. This apparent adjustment to the food resource that usually prevails is sometimes inadequate, for as Craighead and Craighead (1956, p. 226) observed, “There are many examples of hawks and eagles returning to previous nesting territories and attempting to raise broods where there was not sufficient food to support them.”
Redtail breeding populations are distributed throughout most wooded regions of the United States and Canada south of the tundra. As a predator, this raptor is a generalist, taking a great variety of prey. One might thus expect that it seldom experiences food shortage. Our studies at Rochester suggest, however, that this may not be true for northern redtails occupying habitats in which Snowshoe Hares are strongly cyclic.
We estimated earlier, for example, that malnutrition caused about 50% of the nestling losses within 3-4wk after hatching. We concluded too that approximately 70% of the annual variance in such mortality could be attributed to differences in the biomass of food supplied to nestlings and the frequency of rain. The former was largely determined (r? = 0.89) by the biomass of Snowshoe Hare, which was in turn largely determined (r2=0.89) by hare population densities.
Despite the fact that their prey base has a major cyclic component, breeding populations of northern redtails exhibit the same numerical stability and reproductive persistence that characterizes redtails and other temperate-zone raptors further south. The lack of any notable reproductive response to changing hare densities suggests to us that reductions in food during hare declines become critical to nestling survival only when associated with above-average rain- fall after hatching. The latter is a post facto random event for which an accommodating reproductive strategy could not likely evolve.
In contrast, Great Horned Owls at Rochester have a breeding strategy that is clearly adapted to the hare cycle (Adamcik et al. 1978) and differs sharply from the evident constancy of
1979
reproduction among horned owl populations further south. As McInvaille and Keith (1974) noted, northern horned owls unlike redtails, “... are year-round residents, subject to the stresses of cold and potential food-shortage during winter. When hares and grouse are scarce there are few alternative and available prey species. Most small-mammal activity is sub- nivean, and there is a paucity of overwintering songbirds.”
Under these circumstances, cyclic lows in hare populations are certain to affect the owls’ physical and/or physiological condition and hence their rate of breeding in late winter (March). When Snowshoe Hares were scarcest, as in 1974 and 1975, horned owls at Rochester laid no eggs, whereas during the 1968-1972 period of moderate-to-high hare populations all pairs produced and incubated a clutch. Such variable reproduction combined with ap- preciable ingress and egress generated a four- fold change in numbers of resident pairs over the 10-yr cycle of the hare (Adamcik et al. 1978).
The population dynamics of horned owls in the boreal forest ecosystem thus resemble those of arctic raptors (high mobility, conspicuous density, and reproductive changes), while breeding populations of northern redtails retain the characteristic stability of temperate-zone raptors.
Acknowledgments
The financial support for this study was provided by the University of Wisconsin, College of Agricultural and Life Sciences; the Research Council of Alberta; the Canadian Wildlife Service; the National Science Founda- tion (Grant GB-12631); and the Green Tree Garden Club, Milwaukee.
Literature Cited
Adamick, R.S., A. W. Todd, and L.B. Keith. 1978. Demo- graphic and dietary responses of Great Horned Owls during a Snowshoe Hare fluctuation. Canadian Field- Naturalist 92(2): 156-166.
Clark, P. J. and F.C. Evans. 1954. Distance to nearest neighbor as a measure of spatial relationships in popu- lations. Ecology 35(4): 445-453.
Craighead, J.J. and F.C. Craighead, Jr. 1956. Hawks, owls and wildlife. The Stackpole Company, Harrisburg. 443 pp.
Fitch, H.S., F. Swenson, and D.F. Tillotson. 1946. Behavior and food habits of the Red-tailed Hawk. Condor 48(5): 205-237.
ADAMCIK ET AL.: RED-TAILED HAWKS AND SNOWSHOE HARES Di
Gates, J.M. 1972. Red-tailed Hawk populations and ecology in east-central Wisconsin. Wilson Bulletin 84(4): 421-433.
Hagar, D.C., Jr. 1957. Nesting populations of Red-tailed Hawks and horned owls in central New York state. Wilson Bulletin 69(3): 263-272.
Henny, C. J. and H.M. Wight. 1972. Population ecology and environmental pollution: Red-tailed and Cooper’s Hawks. /n Population ecology of migratory birds. United States Department of the Interior, Bureau of Sport Fisheries and Wildlife, Research Report Number 2. pp. 229-250.
Henny, C. J., F. C. Schmid, E. M. Martin, and L. L. Hood. 1973. Territorial behavior, pesticides, and the population ecology of Red-shouldered Hawks in central Maryland, 1943-1971. Ecology 54(3): 545-555.
Johnson, S. J. 1975. Productivity of the Red-tailed Hawk in southwestern Montana. Auk 92(4): 732-736.
Keith, L. B., A. W. Todd, C. J. Brand, R. S. Adamcik, and D.H. Rusch. 1977. An analysis of predation during a cyclic fluctuation of Snowshoe Hares. 13th International Congress of Game Biologists. pp. 151-175.
Keith, L.B. and L. A. Windberg. 1978. A demographic analysis of the Snowshoe Hare cycle. Wildlife Mono- graphs Number 58. 70 pp.
Luttich, S.N., L. B. Keith, and J.D. Stephenson. 1971. Population dynamics of the Red-tailed Hawk (Buteo jJamaicensis) at Rochester, Alberta. Auk 88(1): 75-87.
Luttich, S. N., D. H. Rusch, E. C. Meslow, and L. B. Keith. 1970. Ecology of Red-tailed Hawk predation in Alberta. Ecology 51(2): 190-203.
McInvaille, W. E. and L. B. Keith. 1974. Predator-prey relations and breeding biology of the Great Horned Owl and Red-tailed Hawk in central Alberta. Canadian Field- Naturalist 88(1): 1-20.
Meslow, E. C. and L. B. Keith. 1966. Summer food habits of Red-tailed Hawks near Rochester, Alberta. Canadian Field-Naturalist 80(2): 98-100.
Newton, I. 1976. Population limitation in diurnal raptors. Canadian Field-Naturalist 90(3): 274-300.
Orians, G. and F. Kuhlman. 1956. Red-tailed Hawk and horned owl populations in Wisconsin. Condor 58(5): 371-385.
Rusch, D. H., E. C. Meslow, P. D. Doerr, and L. B. Keith. 1972. Response of Great Horned Owl populations to changing prey densities. Journal of Wildlife Management 36(2): 282-296.
Seidensticker, J.C., IV and H.V. Reynolds, III. 1971. The nesting, reproductive performance, and chlorinated hydrocarbon residues in the Red-tailed Hawk and Great Horned Owl in south-central Montana. Wilson Bulletin 83(4): 408-418.
Smith, D. G. and J. R. Murphy. 1973. Breeding ecology of raptors in the eastern Great Basin of Utah. Brigham Young University Science Bulletin, Biological Series 18(3): 1-76.
Tubbs, C. R. 1974. The buzzard. David and Charles Ltd., London. 199 pp.
Received 8 May 1978 Accepted 18 September 1978
The Oriskany Sandstone Outcrop and Associated Natural Features, a Unique Occurrence in Canada
DIANNE FAHSELT,! PAUL MAYCOCK,? GORDON WINDER,? and CRAIG CAMPBELL4
'Department of Plant Sciences, University of Western Ontario, London, Ontario N6A 3K7 2Department of Botany, Erindale College, University of Toronto, Mississauga, Ontario LSL 1C6 3Department of Geology, University of Western Ontario, London, Ontario N6A 3K7
4421 King Street North, Waterloo, Ontario N2J 3Z4
Fahselt, D., P. Maycock, G. Winder, and C. Campbell. 1979. The Oriskany sandstone outcrop and associated natural features, a unique occurrence in Canada. Canadian Field-Naturalist 93(1): 28-40.
An unusual type of oak-hickory forest not reported previously in Ontario has been found growing on sandstone in the southern part of the province. The sandstone is the middle Lower Devonian Oriskany Formation (approximately 380 million years old), a unit which crops out to no significant extent anywhere else in Canada and is found only toa very limited degree in the subsurface. This highly fossiliferous outcrop has a total areal extent of less than 250 ha (1 mi’), most of it either under a thin cover of sandy soil or exposed as actual outcrop. Although the site is very dry it is unusually rich in plant species composition; at least 40 tree species grow in the area including an unusually large representation of oaks. There is an unexpectedly large number of understorey species for a dry forest. Some species in the understorey are more northerly elements that are quite uncommon in southern Ontario; others are southern species which are rare throughout their range in Ontario. A number of prairie associates are present as well. Twenty-two of the plants are rare in Ontario. The site serves as habitat for Elaphe obsoleta obsoleta(Black Rat Snake), one of the largest species of snake in Canada, whose southern Ontario populations are declining.
Key Words: Oriskany, sandstone, oak-hickory forest, big-shell community, brachiopods, Black Rat Snake.
The objective of this paper is to outline some outcrops of Oriskany sandstone are indicated on of the outstanding natural features of the older geological maps (Stauffer 1915; Caley Oriskany outcrop in southern Ontario. The 1940) but just one, the largest of these, has been biologically important aspects of the site, which — verified as Oriskany using modern petrographic have been identified only recently, are in criteria (J. F. Cowan, 1977, unpublished data, imminent danger of being lost owing to quarry- University of Western Ontario). Only the one ing by the Flintkote Company of Canada. An authenticated exposure is shown on recent maps “environmental protection area” has been selec- (Sanford 1969; Hewitt and Liberty 1972; Telford ted by the company and will remain under 1975). This outcrop of flat-lying sediments, company ownership, but it contains little of located about 3.0 km NE of the village of Nelles biological significance. Quarrying of the area is Corners, Regional Municipality of Haldimand- recommended by the Ontario Municipal Board Norfolk, Ontario (42°56’N, 79°57’W) is shown and approved by the Ontario Ministry of as an irregularly shaped area with an average Natural Resources. Zoning by-laws were modi- diameter of approximately 1.5 km. Air photos fied in June 1978 to permit aggregate extraction and field observations, however, reveal that the at the Oriskany site, although the Regional outcrop is actually even more limited than the Municipality of Haldimand-Norfolk now desig- recent maps suggest. The greater part of the nates it as an environmentally unique ecological formation does not occur as an actual outcrop,
area. but is covered either by the younger Bois Blanc Formation or glacial till. Figure | shows an Geology estimate of the areal extent of the outcrop at the
The Oriskany Formation occurs to a very — surface and in the subsurface. This sketch was limited extent in southern Ontario but in no drawn on an air photo base using observations other part of Canada. A number of small made by ground reconnaissance.
28
1979
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FIGURE 1. Sketch based on an air photo showing the Oriskany outcrop area near Nelles Corners, Ontario. Estimated limits of Oriskany sandstone in the subsurface are shown by a broken line. Vertical hatching represents Oriskany overlain by the Bois Blanc Formation; the unhatched portion represents Oriskany at the surface or directly under the soil. The locations of study sites I-IV (Tables | and 2) are indicated, as well as the open prairie area (P).
30 THE CANADIAN FIELD-NATURALIST
There is one unmapped occurrence of authen- tic Oriskany at “Shoap’s Farm” about 2.4 kmSE of Springvale, Ontario (42°57’N, 80°97’W) (Parks 1913), which consists of a vertical face only a few metres in length. As it has no horizontal exposure, it reveals only limited geological information and has little influence on native plants growing on the surface. Thus, the small Springvale outlier is of relatively little significance.
The Oriskany sandstone outcrop near Nelles Corners is a flat-lying erosional remnant which is now separated by a distance of 100 km from the edge of the continuous Oriskany in the subsurface south of Lake Erie (Figure 2). The
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Vol. 93
type locality is at Oriskany Falls, southwest of Utica, New York. The New York correlation chart (Rickard 1975) shows the formation as part of the Deerparkian Stage (or the Siegenian, in European terminology) which is middle Lower Devonian or in absolute terms, about 380 million years old. This is an exceptionally coarse-grained sandstone consisting mostly of quartz with some feldspar. The quartz grains are well rounded and closely packed with a mini- mum of cement, which near the top of the formation may be calcite. The degree of cemen- tation is variable and the rock tends to be friable at the surface where the rock is subject to frost action. The unit is very massive occurring in beds
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FiGURE 2. Geographic extent of the Oriskany Sandstone Formation. The stippled area represents Oriskany in the subsur- face south of the Great Lakes. Isolated erosional remnants are indicated where they crop out in New York State and Ontario. Constructed from Rickard (1975), Kreidler (1964), and Lytle (1964).
1979
up to 100cm thick, which break out in large blocks along vertical joint planes. The rock is porous but rain falling on the surface runs laterally and disappears down joints or passes through to the underlying Bass Islands Forma- tion. The permanent water table is 16-20 m below the surface. The imminent quarrying operation would be carried out above the water table.
Although fossil preservation 1s rather unusual in a coarse sandstone, parts of the Oriskany are highly fossiliferous. There are internal as well as external molds which show both interior and exterior characters of the shells. Fossils at the Nelles Corners site have been identified by Stauffer (1915), Caley (1940), and Best (1953) and include brachiopods, corals, trilobites, gastropods, pelecypods, and miscellaneous forms. Index fossils characteristics of the Oris-
FAHSELT ET AL.: ORISKANY SANDSTONE OUTCROP FEATURES 31
kany sandstone include Acrospirifer, Costispiri-
fer, Hipparionyx, Rensselaeria, and Oriskania
(all brachiopods) (Figures 3-7). Some genera can be found in both North America and Europe (e.g., Acrospirifer), and others are reported only from eastern North America (e.g., Hip- parionyx). The large brachiopods that dominate the fossil fauna and are referred to as a “big shell community” (Boucot and Johnson 1967) are not found in any other Canadian sandstone. Of the more than 75 fossil species reported, only about one third occur elsewhere in Ontario or Quebec.
Unconsolidated rock materials over the out- crop are mainly of glacial origin and are either nonexistent or very thin. The site is therefore not suitable for agriculture and 1s largely covered by open woods known locally as the Clanbrassil Forest. The biological significance of the area was not realized until relatively recently.
FIGURES 3-7. Index fossils characteristic of the Oriskany 6, Rensselaeria; 7, Costispirifer.
Formation. 3, Hipparionyx; 4, Acrospirifer; 5, Oriskania,
By THE CANADIAN FIELD-NATURALIST
Vegetation
The first indications that the vegetation was in any way unusual were the observations of F. S. Cook (University of Western Ontario, personal communication 1976) who noted the presence of saxicolous mosses which are rarely seen in southern Ontario because their required sub- strate is essentially unavailable. Outcrops most common in southern Ontario are associated with the Niagara Escarpment and they are mainly limestone and dolostone. These rocks differ markedly from sandstone in their calcium content, the pH of materials derived from them by weathering, and their suitability for certain kinds of plant growth.
Open oak-hickory forest growing on sand- stone bedrock is very unusual for Ontario. In order to develop a precise idea concerning the structure and composition of the forest, the vegetation was examined in detail and part of the area was sampled quantitatively.
Methods
Five homogenous areas ranging in size be- tween about 2 and 6 ha were selected. Four were forested and one was an opening within the forest. A list was compiled of all trees, shrubs, and herbs in each forested area. Two of the larger areas were sampled quantitatively using the Point Quarter Method (Curtis 1959); 30 sampling points were scattered at random throughout each site. Around each point four trees and four saplings were randomly selected in each of four quadrants, 1.e., the nearest speci- mens to the center point in each quadrat were selected. At every other point a sample of the ground layer was taken by recording presence (frequency) in metre-square quadrats. A number of environmental features as well as additional structural and compositional details of the vegetation were recorded when the sampling procedure was completed.
A frequency value was determined for each tree species on the basis of its percentage occurrence at points. These values were summed for all tree species and the contribution of an individual species to that sum was calculated asa percentage (= relative frequency). Similarly, the number of stems contributed by a species at points of occurrence was calculated as a per- centage of the contribution of all species at all
Vol. 93
points (= relative density). The total basal area for one species was calculated as a percentage of basal area for all species (= relative dominance). The three values for a given species, relative frequency, relative density, and relative domin- ance, were combined to give its importance value. This is a precise measure of the ecological influence of a tree species in the forest.
In the forest openings lists were taken of all vascular plants present, and general observa- tions on community structure and environ- mental features were recorded.
Parts of the outcrop along Townline Road (Figure 1) were badly disturbed with old foundations, old buildings, small abandoned quarries, and road systems. Because much of the associated vegetation was weedy, it was not examined in the same way as other sites within the general area.
Results and Discussion
Open oak-hickory communities (Figure 8) of the type located near Nelles Corners on sand- stone bedrock had not previously been found during an extensive survey of forest vegetation of southern Ontario (Maycock 1963). At least 28 different tree species are found in the stands sampled on the Oriskany outcrop area (Table I). This is considerable diversity for sucha poor dry site.
At Site I (Figure 1) where the soil is very shallow there are no clear-cut dominants but Quercus velutina (Black Oak), Q. rubra (Red Oak), Prunus serotina (Black Cherry), Quercus alba (White Oak), and Carya ovata (Shagbark Hickory) are the major tree species. The source of names used in the text and iables is Fernald (1950). All 28 tree species are found in Site 1, but more than half of stand importance is accounted for by oaks which together have an importance sum of 163 (Table 1). In the sapling’ layer Fraxinus americana (White Ash), Prunus sero- tina, Amelanchier arborea (Serviceberry), and Acer saccharum (Sugar Maple) are well repre- sented. All of the oaks are represented to a limited extent in the sapling layer (approxi- mately 20% of sapling-density) but are less important here than in the tree layer. Hickory reproduction appears to be maintaining the status of this species. A rich assortment of tall shrubs is found including (listed in order of
is y Ne ; nie me j 9 @
FAHSELT ET AL.: ORISKANY SANDSTONE OUTCROP FEATURES 33
FIGURE 8. Open oak-hickory forest on sandstone at the Oriskany outcrop in southern Ontario. The best of these stands are presently scheduled for quarrying by King Paving and Materials of Burlington, Ontario, a Division of the Flintkote
Company of Canada.
decreasing dominance) Cornus racemosa (Race- mose Dogwood), Amelanchier arborea, Vibur- num rafinesquianum (Downy Arrow-wood), Prunus virginiana (Choke-cherry), and Vibur- num acerifolium (Maple-leafed Viburnum). Pyrus coronaria (Wild Apple) is one uncom- mon species of note. Amelanchier arborea does not often attain tree sizes but in this stand there are a number of large specimens. There is also a rich tall herb layer which includes Preridium aquilinum (Brake), Solidago caesia (Blue-stem Goldenrod), and Aster sagittifolius (Arrow- leafed Aster), and a low herb layer with Carex pensylvanica, Galium aparine (Cleavers), and G. circaezans (Wild Licorice). In total 108 species of herbs and shrubs are present. Lichens are uncommon in forests of the deciduous forest regions but both lichens and mosses are locally abundant in Site I.
Site II is immediately below Site I on a gradual south-facing slope and also has shallow soils. The dominant trees are Red Oak and White Oak with a lesser representation of Shagbark Hickory and Black Cherry. Black Cherry, Shagbark Hickory, and Red Oak are well represented in the sapling layer, while Cornus racemosa and Prunus virginiana are important elements in the shrub layer. In the medium-height herb layer Solidago caesia and Geranium maculatum (Wild Cranesbill) are found, and in the low herb layer are Maian- themum canadense (\wo-leafed Solomon’s- seal), Carex pensylvanica, and Aster macro- phyllus (Large-leafed Aster). This is also a dry complex with considerable diversity including 24 tree species and 87 herbs and shrubs.
Site III is just south of Site II toward the bottom of the gentle slope. In Site III the
34 THE CANADIAN FIELD-NATURALIST
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TABLE |—Tree species growing in selected stands at the Oriskany outcrop area. Locations of the four sites are shown in Figure |. Presence is indicated by plus signs and importance values (defined in text) for the two larger sites are given in parentheses
Species
] Acer nigrum (Black Maple) + Acer rubrum (Red Maple) + (4) Acer saccharum (Sugar Maple) + (9) Amelanchier arborea (True Serviceberry) + (20) Carpinus caroliniana (Ironwood) + (3)
Carya cordiformis (Bitternut Hickory) + Carya ovata (Shagbark Hickory) Celtis occidentalis (Hackberry) + Crataegus chrysocarpa (Hawthorn) + Crataegus sp. (Hawthorn) ste Fagus grandifolia (Beech) - Fraxinus americana (White Ash) + (17) Juglans nigra (Black Walnut) + Juniperus virginiana (Red Cedar) + Ostrya virginiana (Hop-hornbeam) + Pinus strobus (White Pine) + Populus grandidentata (Large-tooth Poplar) + Populus tremuloides (Trembling Aspen) P Prunus cerasus (Cherry) + Prunus serotina (Black Cherry) tp Pyrus coronaria (Wild Apple) at Quercus alba (White Oak) Quercus macrocarpa (Bur Oak) F Quercus muehlenbergii (Chestnut Oak) Quercus rubra (Red Oak) Quercus velutina (Black Oak) Tilia americana (Basswood) Ulmus americana (White Elm) + Total trees 28 Total herbs and shrubs 108
Soil pH 4.6-7.0 Depth A, (cm) 6 Depth B (cm) 13 Moisture dry
Sites
I] Il] IV + (3) + (3) + + + (18) a + (3) + + + + (7) + (21) + + fi A
+ + (1) + + i 2 + (15) + + (4) + + + (6) + + + (5) + (19) + + 4 + (78) + + + (4) + + (86) + + se (112) 7 + (8) + + 24 13 12 87 45 27 8.0 Usd) 6.4-7.8 8 10 10 10 48 18 dry—mesic dry—mesic mesic
unconsolidated surface soil is deeper (see Table 1) than in either Site I or I]. White Oak and Shagbark Hickory are the two dominant trees and scattered Black Cherry is also found. In the sapling layer cherry and White Oak are well represented. Prominent tall shrubs are Cornus racemosa and Viburnum acerifolium, while herbs include Aster macrophyllus, Carex pen- sylvanica, Galium aparine, and Potentilla sim- plex (Old-field Cinquefoil). In total there are 13 tree species in Site II] and 45 species of herbs and shrubs.
Site IV, like Site III, is on deeper soil. The dominants are Sugar Maple and Red Maple
with some White Oak, White Ash, and Red Oak. This stand is heavily shaded and the saplings are mostly maple. The low shrub layer is very sparse and includes scattered Viburnum acerifolium. The only herbs are low and include Carex pensylvanica, C. pedunculata, and Solidago caesia. There are 12 tree species represented in Site IV and 27 herbs and shrubs. There are few mosses or lichens.
In the forest openings, common dominants are Cornus racemosa, Danthonia spicata (Pov- erty Grass), Rhus typhina (Staghorn Sumac), Prunus virginiana, Desmodium canadense (Canadian Tick-trefoil), Hypericum perforatum
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(St. John’s-wort), Solidago canadensis (Can- adian Goldenrod), and S. juncea (Stiff Golden- rod). One of the openings (P in Figure 1) is of particular interest because of its high component of dry prairie elements, notably Lespedeza intermedia (Intermediate Bush-clover), L. capi- tata (Headed Bush-clover), Polygala verticillata (Whorled Milkwort), P. pol/ygama(Polygamous Milkwort), Desmodium paniculatum (Panicu- late Tick-trefoil), D. rotundifolium (Round- leafed Tick-trefoil), D. dillenii, Galium pilosum, Linum vriginiana (Virginian flax), Andropogon gerardi (Gerard’s Beardgrass), Monarda fistu- losa (Wild Bergamot), Physalis heterophylla (Variable-leafed Groundcherry), Solidago nem- oralis (Woodland Goldenrod), Panicum lineari- folium (Linear-leafed Panic Grass), and Aster ericoides.
The Oriskany outcrop is considered to be a drier-than-average site for southern Ontario. If sites in the province were ranked along a continuum according to water availability, the Oriskany outcrop would be the driest of those capable of supporting forest. The trees are rather widely spaced approaching a condition inter- mediate between forest and savanna. The open condition of the canopy results in high light intensities within the stand and permits repro- duction of species such as Black Cherry, hickory and oaks, as well as heavy shrub and herb layers.
Populus grandidentata (Large-toothed Pop- lar) is one species found at the site that 1s usually characterized by a very shallow rooting system. Many of the dominants, however, are species able to form long tap roots. For example Quercus velutina, Q. alba, and Carya ovata all produce vigorous primary roots early in devel- opment enabling the seedlings or young saplings to withstand drought conditions. Quercus rubra is another species represented at the site that is capable of producing deeply penetrating tap roots (Fowells 1965). Pinus strobus (White Pine) typically produces just the vestige of a tap root but has several large laterals extending outwards and down (Fowells 1965). White Pine root systems have been shown to penetrate toa depth of 4.5 m (Brown and Lacate 1961).
Many trees and shrubs are first- or second- collection records for the Haldimand County which close gaps in the distributional patterns
FAHSELT ET AL.: ORISKANY SANDSTONE OUTCROP FEATURES 35
for species both east and west. Thus the site has phytogeographical significance.
In the Oriskany outcrop area, the favorable sites with deeper soil are definitely less diverse in tree species. On better sites more dominance is exerted by fewer species. Greater moisture, more favorable pH, and perhaps better nutrition contribute to this pattern of tree occupancy. Species diversity is much greater in sites with shallow soils (e.g., I and II). At these sites there are a number of major tree species but no clear dominants, and there are far greater numbers of shrub and herb species. Diversity is undoubtedly related to the great variety of microhabitat available for plants. Some rock surfaces are exposed, others are covered with thin soil. The soil depth varies and the shallower soils have a low pH due to sandstone and absence of carbonate rocks providing opportunities for acid-loving plants, conditions which are seldom available in southern Ontario.
The maple stand (Site IV) is on deeper soil and is representative of a type of vegetation very common in southern Ontario. The interesting species of the sandstone outcrop type are absent. The sites of most value botanically are very heterogenous at the ground surface, 1.e., those with shallow acidic soil over sandstone. The age of older trees in the maple stand is approxi- mately the same as the age of older trees in the other forested sites studied.
The openings adjacent to the forest stands have allowed the invasion of dry prairie ele- ments, further adding to the diversity of the area. The high diversity indicates that there may be other unusual species or communities in ad- jacent areas. For example, the Dry Lake area nearby has an interesting assortment of thicket and seasonal meadow communities. Quercus bicolor (Swamp White Oak) is one uncommon species that has been found in the lowland fringes of Dry Lake.
One group of rare and notable plants occur- ring in the outcrop area consists of more northern species that are quite uncommon in southern Ontario, although they may be wide- spread northward, and the other is composed of southern species that are rare throughout their range in Ontario. Northern species such as Hairgrass (Deschampsia flexuosa) and Running
36 THE CANADIAN FIELD-NATURALIST
Clubmoss (Lycopodium clavatum) are without doubt present here owing to the sandstone substrate and are otherwise quite rare in south- ernmost Ontario. Because of its southern loca- tion, the site also contains a number of un- common species that are members of the Carolinian flora of Ontario. This flora occupies the region directly north of Lake Erie to a sinuous line from Toronto through London to Port Franks on Lake Huron. Examples of such species in this area are Wild Crab (Pyrus coronaria), Black Walnut (Jug/ans nigra), Hack- berry (Celtis occidentalis), and Chestnut Oak (Quercus muhlenbergii). In summary, the unique vegetational status of the area is com- plemented by the presence of a number of rare and interesting species. Twenty-two of the species found in the Oriskany outcrop area are among those that have been listed as rare by Argus and White (1977) (Table 2). It is most unusual to find such a large number of rare plants concentrated in so small an area.
Habitat for the Black Rat Snake
The presence of unusual forest associations and unusual understorey plants provides a particular habitat for wildlife. The most notable animal known to inhabit the Oriskany site 1s the
Vol. 93
Black Rat Snake (Elaphe obsoleta obsoleta), the largest species of snake in Canada. The Black Rat Snake is considered rare, threatened, or endangered in Ontario and Canada by several authors (Campbell 1969; Cook 1970a; Anony- mous 1970; Froom 1972; Stewart 1974; Parsons 1976; Cook 1977; Gregory 1977).
Observations of Elaphe obsoleta at the out- crop were made by W. W. Judd (University of Western Ontario) in 1976 and J. Webber (Erindale College, University of Toronto) in 1977, and by at least four local residents during the past two years. Judd observed a snake at close range for about | min; Webber was able to sketch anatomical details from a distance of 2 ft. One local person observed many snakes (of varying sizes) simultaneously in the spring of NSE
It should be noted that the combination of rocky terrain and extensive relatively undis- turbed forested area such as that found at the Oriskany site constitutes ideal habitat for the Black Rat Snake. Knudsen (1955) stated that the Black Rat Snake inhabits areas that have an abundance of rocky areas and crevices, and from these sites they venture out into nearby agri- cultural lands. The snake is sometimes con- sidered a forest species (Hay 1892; Morse 1904;
TABLE 2—Rare plants (Argus and White 1977) found at the Oriskany outcrop. Areas are those shown on Figure |
Species
Asplenium platyneuron Panicum lanuginosum var. praecocius Carex laxiflora var. gracillima Disporum lanuginosum Polygonatum biflorum Juglans nigra
Quercus bicolor
Quercus muehlenbergii Ranunculus hispidus
Arabis canadensis
Prunus americana Desmodium rotundifolium Lespedeza intermedia
Linum virginianum
Viola pedata var. lineariloba Thaspium barbinode Vaccinium pallidum (V. vacillans) Asclepias exaltata
Conopholis americana
Galium pilosum
Swertia caroliniensis
Aster pilosus
Common name Area found Ebony Spleenwort I Woolly Panic Grass P V Fairy Bells II Solomon’s Seal II Black Walnut I Swamp White Oak V Chinquapin Oak II Stiffly-hairy Buttercup I Sickle-pod ] Wild Plum 111 Round-leafed Tick-trefoil I Intermediate Bush-clover Pp Virginia Flax le Bird-foot Violet IP Meadow Parsnip Vv Hillside Blueberry I II Squawroot I I American Columbo V P
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Wright and Wright 1957; Fitch 1963); Wright and Wright (1957) and Fitch (1963) both mention occurrences associated with oak-hick- ory forests. Nearly half of the location records for radio-implanted specimens (Fitch 1963) were in trees while others were in burrows, low vegetation, or buildings. At the Oriskany site approximately 300 ha (3 km2) including the outcrop and immediately adjacent areas are considered suitable habitat.
In Ontario, there are now two main isolated ranges for the Black Rat Snake. The one in the Kingston ~ Rideau Lakes area is maintaining itself to some degree, but the range in south- western Ontario is clearly discontinuous despite maps (e.g., Conant 1975) indicating a continu- ous range along Lake Erie. In southwestern Ontario, there are only a few small isolated locations which are considered by C. A. Camp- bell to be sites of Black Rat Snake populations. These with dates of sightings in parentheses are (1) Essex County: Point Pelee, Pelee Island (1977), (2) Kent and Middlesex County: Skunk’s Misery (1968, 1974), (3) Haldimand-Norfolk Regional Municipality: the western part of the former Norfolk County (the main center of abundance) (1940-1978) and other locations including the Oriskany site (1976-1978), and (4) Niagara Region: Fonthill in the Shorthills area (1928-1976). Even at these locations the snakes are not abundant; they are threatened by agriculture and a multitude of other human activities. Clearly, the number of large snakes in southwestern Ontario is seriously declining, as 1s the available habitat. There is no evidence that the Oriskany population is continuous with others in Ontario. Further details on the Black Rat Snake in Ontario are in an unpublished report by C. A. Campbell (1977) entitled “The status of the Black Rat Snake Elaphe obsoleta obsoleta in Ontario and particularly in the Haldimand-Norfolk Region” (available from C. A. Campbell or D. Fahselt).
Fitch (1963) calculated that the home range of adults in Kansas is 12 ha for males and 9 ha for females. In Maryland, the average home range of E. obsoleta was estimated to be 18+ha (Stickel and Cope 1947). Small populations are always particularly vulnerable, so the entire forest and outcrop complex must be maintained in its present condition in order to maximize
FAHSELT ET AL.: ORISKANY SANDSTONE OUTCROP FEATURES 37
numbers. Restriction of habitat is listed as one of the three major factors contributing to the decline of Elaphe obsoleta (Cook 1970a, b).
General Discussion Threats to the Area
As the area is unique and interesting in several ways it is useful to consider the impact of likely types of disturbances. First, there is abundant evidence that fires have occurred in the past. Second, it is obvious that exposed bedrock of this nature is an attractive commercial source of mineral aggregate.
(a) Fire
Certainly dry sites such as this are quite susceptible to fire. Within the area blackened stumps or charcoal in the soil are evident at various locations. Though some scattered trees are older than 90 yr, it is clear that neither the oak nor maple forest represents an advanced state of succession. Few of the trees are large, most having basal areas of 516 mm2 (80 in2) or less. Fire may be one of the factors responsible for maintaining the oak-hickory forest in its present secondary successional state; burning would permit oaks, hickories, and Large- toothed Poplar to persist and predominate. Y oung oaks and hickories, and to a lesser extent even mature trees, sprout vigorously after the tops are killed back to the ground by burning (Fowells 1965); and fire may help to perpetuate Populus grandidentata as well as some of the prairie elements. Periodic burning may be partially responsible for maintaining the present successional state of the stand and contributing to the diversity of the interesting plant species. Selective logging at the site may have produced a similar effect.
(6) Commercial quarrying
Beneath the Oriskany formation at the Nelles Corners site is approximately 15m of dolo- stone, a calcilum-magnesium carbonate (the Bass Islands Formation), which is desirable as aggre- gate for paving and building. Quarrying would remove the sandstone formation upon which the oak-hickory forest depends. The forest could not re-establish itself afterward on the freshly ex- posed rock surfaces of the quarry floor because soil chemistry and water availability would be
38 THE CANADIAN FIELD-NATURALIST
quite different. Also there would be cold air drainage into the quarry bottom. If commercial removal of dolostone does take place an excava- tion with sheer vertical faces would result and this would have adverse effects on any peripheral remnants of forest. The edge effect associated with a disturbance as drastic as quarrying would likely be much more pronounced in a dry area such as this than it would in a mesic site. The establishment of a preserve for the fossiliferous portion of the Oriskany outcrop would not have a sufficiently large geographic area to support the unique plant communities such as those in Sites I and II, nor would it be suitably placed to include them.
Another problem associated with a possible quarry operation would be the effects of wind- blown particulates. Dust reduces available light and in some cases reacts with water to form toxic solutions. Trees growing near a source of carbonate dust were reported to have reduced terminal growth (Manning 1971) or to be ina generally poor condition (Brandt and Rhoades 1972). Particulate interference with stomatal behavior seriously affects the diffusion resis- tance of leaves and changes the rates of gaseous exchange (Ricks and Williams 1974). This could aggravate moisture stress on sites that are exposed or dry (Smith 1974). The rates of degradation of photosynthetic pigments in the leaves of Quercus petraea were significantly changed owing to particulate pollutants (Ricks and Williams 1975) and senescence occurred earlier at the polluted sites. Leaves with moder- ate limestone dust deposits had a greater incidence of fungal leaf spots (Manning 1971), and plants dusted with cement-kiln dust were more susceptible to fungus leaf spot disease (Schonbeck 1960).
A numerical model which predicts the rate of dispersion of atmospheric particulates and the amounts of deposition in wooded areas was described by Belot et al. (1976). A forest canopy significantly increases the concentration of par- ticulates deposited near the source. It is pre- dicted that maximal deposition would occur within | km of dust-producing activities.
Tree species respond differentially to dust accumulation. Brandt and Rhoades (1973) have shown that while lateral growth of Liriodendron
Vol. 93
tulipifera (Tulip Tree) was increased as a result of deposition of dust from nearby limestone quarries and processing plants, Quercus prinus, Q. rubra, and Acer rubrum underwent a reduction in lateral growth. Therefore, in a mixed stand involving these species, importance values would be altered with time. In fact Brandt and Rhoades (1972) documented significant differences in the seedling-shrub and sapling strata between two comparable sites, one witha heavy accumulation of limestone from quarries and processing plants and the other a control area with no dust accumulation. The dominant species at the dusty site would therefore change with continued dust accumulation. The papers by Brandt and Rhoades indicate that it would be difficult to maintain a natural balance among tree species in a forest adjacent to a sustained source of heavy limestone dust.
It cannot be imagined that quarrying would have anything but a detrimental effect on Elaphe obsoleta. First, the snake is susceptible to road- kill (Fitch 1963). Second, it retreats with the advent of disturbance to wooded areas (Morse 1904; Minton 1968). Quarrying would lead to an obvious loss of suitable habitat.
Synopsis
We have emphasized the geological impor- tance of the Oriskany Formation in Canada and provided some indication of the unusual nature of this forest tract and its richness in tree and other plant species as well as its unusual structural and compositional features. We have also attempted to show its value as a habitat for the Black Rat Snake. The Oriskany site repre- sents the on/y example of oak-hickory forest on sandstone in Ontario. It is decidedly unique in representing a dry upland type of oak-hickory forest not recognized in Ontario. The oak- hickory type in Ontario is usually associated with heavy clay soils which have peculiar drainage and moisture features and never seems to approach a classical dry oak-hickory type as does the existing example at Nelles Corners. This feature coupled with the large number of unique and interesting plant occurrences, es- pecially the unusually large number of oak species, combines to produce a natural area of great value and interest, and one which should
1979
be given complete protection. Preservation of the entire area would be consistent with the adopted policy statement of the Canadian Institute of Forestry (Weetman 1972) that 123-410 ha (300-1000 acres) is a highly desir- able size for forested natural areas. Interesting natural features, geological and biological, oc- cur throughout the Oriskany outcrop area, so it is particularly crucial in this case that a large preserve be set aside.
The Flintkote Company has selected an “environmental protection area” of 19 ha (47 acres) to be located along Townline Road, the southern boundary of the quarry site. This selection has been approved by the Ontario Municipal Board and by the Ontario Minister of Natural Resources. The area does contain features of geological interest but, because of its very small size and the disturbances there, it is of virtually no importance biologically.
Acknowledgements
Maycock, Winder and Fahselt acknowledge the financial assistance of the National Research Council of Canada.
Literature Cited
Anonymous. 1970. Table of extinct, rare and endangered vertebrates in Ontario. Ontario Fish and Wildlife Review 9: 15-21.
Argus, G. W. and D.J. White. 1977. The rare vascular plants of Ontario. National Museums of Canada, Syl- logeus Number 14.
Belot, Y., A. Baille, and J.L. Delmas. 1976. Model numérique de dispersion des polluants atmosphériques en présence de couverts végétaux. Atmospheric Environment 10: 89-98.
Best, E. W. 1953. Pre-Hamilton Devonian stratigraphy of southwestern Ontario. Ph:D. thesis, University of Wis- consin, Madison, Wisconsin.
Boucot, A. J. and J. G. Johnson. 1967. Paleography and correlation of Appalachian Province Lower Devonian sedimentary rocks. Tulsa Geological Society Digest 333 35-67-
Brandt, C. J. and R. W. Rhoades. 1972. Effects of lime- stone dust on lateral growth of forest trees. Environ- mental Pollution 4: 207-213.
Brandt, C. J. and R. W. Rhoades. 1973. Effects of lime- stone dust accumulation on composition of a forest community. Environmental Pollution 3: 217-225.
Brown, W.G. E.and D.S.Lacate. 1961. Rooting habits of white and red pine. Forestry Research Branch Technical Note 108. (Available from Department of Fisheries and Environment, Ottawa.)
Caley, J. F. 1940. Palaeozoic geology of the Toronto- Hamilton area, Ontario. Geological Survey of Canada, Memoir 224. pp. 83-87.
FAHSELT ET AL.: ORISKANY SANDSTONE OUTCROP FEATURES 39
Campbell, C. A. 1969. Who cares for the Fowler’s Toad? Ontario Naturalist 4: 24—27.
Conant, Roger. 1975. A field guide to reptiles and am- phibians of eastern and central North America. 2nd edition. Houghton Mifflin Co., Boston.
Cook, F. R. 1970a. Rare or endangered Canadian amphib- ians and reptiles. Canadian Field-Naturalist 84(1): 9-16.
Cook, F. R. 1970b. Endangered wildlife—reptiles and am- phibians. /n Endangered wildlife in Canada. Canadian Wildlife Federation, Ottawa. pp. 10-11.
Cook, F. R. 1977. Review of the Canadian herpetological scene. Proceedings of the Symposium on Canada’s Threatened Species and Habitats. Canadian Nature Fed- eration, Special Publication Number 6.
Curtis, J. T. 1959. The vegetation of Wisconsin. PEON of Wisconsin Press, Madison.
Fernald, M. L. 1950. Manual of botany. American Book Company, New York.
Fitch, H.S. 1963. Natural history of the black ratsnake (Elaphe o. obsoleta) in Kansas. Copeia 1963 (4): 649- 658.
Fowells, H. A. 1965. Silvics of forest trees of the United States. Forest Service, United States Department of Agriculture, Handbook Number 271.
Froom, Barbara. 1972. The snakes of Canada. McClelland and Stewart, Toronto.
Gregory, P. T. 1977. Rare and threatened snake species of Canada. /n Canada’s threatened species and habitats. Canadian Nature Federation, Special Publication Num- ber 6.
Hay, O. P. 1892. The batrachians and reptiles of the state of Indiana. Indiana Department of Geology and Natural Resources Annual Report 17: 409-602.
Hewitt, D.F. and B.A. Liberty. 1972. Map 2254. In Paleozoic geology of southern Ontario. Edited by D. F. Hewitt. Ontario Division of Mines, Geological Report 105.
Knudsen, G. J. 1955. Pilot blacksnake (Elaphe o. obso- leta). Wisconsin Conservation Bulletin 1955 (November): 12:
Kreidler, W. L. 1964. Gas and oil developments in New York State 1963. American Association of Petroleum Geologists Bulletin 48: 778-783.
Lytle, W.S. 1964. Developments in Pennsylvania. Ameri- can Association of Petroleum Geologists Bulletin 48: 784-800.
Manning, W. J. 1971. Effects of limestone dust on leaf condition, foliar disease incidence and leaf surface microflora of native plants. Environmental Pollution 2: 69--76.
Maycock, P. F. 1963. The phytosociology of the deciduous forests of extreme southern Ontario. Canadian Journal of Botany 41: 379-438.
Minton, S.A., Jr. 1968. The fate of amphibians and reptiles in a suburban area. Journal of Herpetology 2(3--4): 113-116.
Morse, M. 1904. Batrachians and reptiles of Ohio. Pro- ceedings of the Ohio State Academy of Science 4(3), Special Paper Number 9: 93-144.
Parks, A. W. 1913. The palaeontology of the Guelph, Onondaga and Hamilton formations in western Ontario. Canada Geological Survey, International Geological
40 THE CANADIAN FIELD-NATURALIST
Congress Field Guide Book Number 4.
Parsons, H. 1976. Foul and loathsome creatures. Parks Canada, Ottawa.
Rickard, L. V. 1975. Correlation of the Silurian and Dev- onian rocks in New York State. New York Science Service Geological Survey, Chart Series 24.
Ricks, G. R.and R. J. H. Williams. 1974. Effects of atmos- pheric pollution on deciduous woodland. Part 2. Effects of particulate matter upon stomatal diffusion resistance in the leaves of Quercus petraea (Mattuschka) Leibl. En- vironmental Pollution 6: 87-109.
Ricks, G. R.and R. J. H. Williams. 1975. Effects of atmos- pheric pollution on deciduous woodland. Part 3. Effects on photosynthetic pigments of leaves of Quercus petraea (Mattuschka) Leibl. Environmental Pollution 8: 97-106.
Sanford, B.V. 1969. Geology: Toronto—Windsor area. Geological Survey of Canada, Map 1263A.
Schonbeck, H. 1960. Beobachtungen zur Frage des Ein- flusses von industriellen Immissionen auf die Krank- bereitschaft der Pflanze. Berichte der Landesanstalt Bodennutzungsschutz (Bochum) |: 89-98.
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Smith, W. H. 1974. Air pollution — effects on the struc- ture and function of the temperate forest ecosystem. Environmental Pollution 6: 111-129.
Stauffer, C. R. 1915. The Devonian of southwestern On- tario. Geological Survey of Canada, Memoir 34.
Stewart, Darryl. 1974. Canadian endangered species. Gage Publishing, Toronto.
Stickel, W. H. and J. B. Cope. 1947. The home ranges and wanderings of snakes. Copeia 1947(2): 127-136.
Telford, P.G. 1974. Dunnville area. Ontario Department of Mines, Map P988.
Weetman, G. F. 1972. Canadian Institute of Forestry poli- cy for selection, protection and management of natural areas. Forestry Chronicle 48: 1-3.
Wright, A.H. and A.A. Wright. 1957. Handbook of snakes of the United States and Canada. Volume I. Comstock Publishing Associates, Ithaca, New York.
Received 19 June 1978 Accepted 19 October 1978
Breeding Areas and Overnight Roosting Locations in the Northern Range of the Monarch Butterfly (Danaus plexippus plexippus) with a Summary of Associated Migratory Routes
FRED A. URQUHART and NORAH R. URQUHART
Life Sciences, Scarborough College, University of Toronto, West Hill, Ontario
MIC 1A4
Urquhart, F. A. and N. R. Urquhart. 1979. Breeding areas and overnight roosting locations in the northern range of the Monarch Butterfly (Danaus plexippus plexippus) with a summary of associated migration routes. Canadian Field-
Naturalist 93(1): 41-47.
Key Words: Monarch Butterfly, breeding areas, overnight roosting locations, northern range, Lepidoptera, Danaidae.
Asa result of over 40 years of investigation dealing with the ecology of the Monarch Butterfly (Danaus plexippus plexippus). with special reference to its migratory habits, it is now possible to outline the major breeding areas in its northern range in Canada and to explain the absence of such areas in the western provinces. The characteristics of the overnight roosting clusters located along the migratory routes are described and compared to those of the overwintering clusters. Asummary of the migratory routes for these northern populations is presented, based on previous published records for North America.
For the past 41 yr, commencing in the summer of 1937, we have been involved in a long-term study of the biology of the Monarch Butterfly, Danaus plexippus plexippus (Danaidae: Lepi- doptera), with special reference to its migratory habits. Although most of our field studies and alar tagging (Urquhart 1941, 1960) have been centered in Ontario, observations have been made in all provinces from Vancouver, British Columbia to Cape North, Nova Scotia. These field surveys were for the purpose of investi- gating the presence, or absence, of breeding areas and, where adults were found, to alar tag them for migratory studies.
It is the purpose of the present paper to summarize our field data for the northern range in Canada, correlating this information with the migratory habit. Because the program has been carried out over a long period of time it has been possible to witness the change in the northern range of the Monarch Butterfly and the increase in its abundance where at one time larvae were unknown or of rare occurrence.
Methods
Field trips were carried out in various locali- ties in each Canadian province and notes made concerning the presence or absence of milkweed plants (Asclepias spp.), the source of food for the
41
larvae of the Monarch Butterfly, and of the larvae and adults of the Monarch Butterfly.
Members of the Insect Migration Association (IMA) sent observations concerning the pres- ence of the larvae and adults of the Monarch Butterfly, together with notes as to their abun- dance in each area.
An alar-tagging program (Urquhart 1960, 1965; Urquhart and Urquhart 1976b) was carried out along with field investigations and by members of the IMA in order to follow the movements of the Monarch Butterfly.
Publicity arising from the recapture of alar- tagged specimens resulted in further observa- tions being sent to us by interested individuals.
All observations and recapture data are on permanent file at Scarborough College, Univer- sity of Toronto.
Results and Discussion
Breeding Range
Field surveys carried out from 1937 to 1940 indicated that breeding areas of the Monarch Butterfly in Ontario were mostly confined to the lower Great Lakes regions extending from Gananoque and Kingston in the east to Goderich in the west and south to Leamington. Large concentrations, owing to the presence of
42 THE CANADIAN FIELD-NATURALIST
dense growths of the Common Milkweed (Asc/e- pias syriaca), were concentrated in the Sarnia- Leamington, Brantford-Hamilton, Toronto- Oshawa, and Belleville regions. Although larvae were collected further north at Barrie and Midland they did not occur in large numbers because growths of the Common Milkweed were not as dense as those found further south.
As a result of the increase in the number of roads and highways and the clearing of forested areas for power lines, the Common Milkweed has gradually spread northward thus increasing the amount of this host plant for the larvae. By 1975 records of large concentrations of both larvae and adults were reported from various locations along the north shore of Lake Superior, particularly at Sudbury, Sault Ste. Marie, and Thunder Bay. Inthe early summer of 1977 larvae were more abundant in the Sault Ste. Marie area than in the T oronto-Oshawa area; we had larvae mailed to our laboratory in Toronto from Sault Ste. Marie in order to carry out various research projects.
The reason for this difference in the numbers of Monarch Butterfly larvae in the Lake Superior regions in the early summer as com- pared to the Toronto-Oshawa area can be explained. We have previously shown (Urquhart and Urquhart 1976d, 1977) that Monarch Butterfly migrants travel in a northwesterly direction in the autumnal migration and north- easterly in the vernal. In this way the migrants reach the north shore of Lake Superior, via Michigan, before arriving in the Ontario penin- sular regions. Since the Common Milkweed 1s now abundant in the Lake Superior regions larger populations of butterflies have occurred here in early summer than further south.
Field surveys each summer from 1962 to 1977 from Toronto north to the northeast shore of Georgian Bay disclosed increasing abundance of the Common Milkweed covering hundreds of hectares along roads, highways, and unculti- vated fields. Also, as a result of the clearing of forested areas, with particular reference to power lines, ever increasing areas have been made available for the further spread of the larval food plant. One experimental plot of 0.5 ha located in a forested area, that had been cleared during lumbering operations, revealed a population of 536 larvae on 15 July 1977.
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For other Canadian provinces records accumulated over the past 41 yr (including 4 yr of field investigations of 1940-1944 in the western provinces and surveys in the eastern provinces together with numerous reports from various interested individuals and members of the IMA) indicate conclusively that there are no breeding areas in British Columbia and Alberta. A few scattered larval populations have been reported for southern Saskatchewan (Duval) and southern Manitoba (Transcona, Furness). Although there have been numerous records of adults seen in Nova Scotia, New Brunswick, Prince Edward Island, and occasionally in Newfoundland, we have no records of any breeding populations there. Three reports have been received from Quebec (Montreal, Drum- mondville, Quebec).
The marked differences among the population numbers in the various provinces are due in part to the migration routes and in part to the distribution of the species of milkweed. Since the migration tends to a northeast-southwest direc- tion from the overwintering Mexican Site (Urquhart and Urquhart 1976d) the migrants miss the western provinces with only a few stragglers being reported. Similarly, the eastern provinces are outside the regular migratory route. Although species of milkweed of the genus Asclepias are found in all provinces, except Prince Edward Island, Labrador, and Newfoundland, the majority of species are found in Ontario where Asc/epias syriaca occurs in the greatest abundance. One species is reported for British Columbia (A. speciosa); there are no records from Alberta: six occur in Manitoba (A. incarnata, A. verticillata, A. ovalifolia, A. syriaca, A. speciosa, A. viridiflora); two occur in Saskatchewan (A. ovalifolia, A. speciosa): 10 occur in Ontario (A. incarnata, A. verticillata, A. tuberosa, A. exaltata, A. quadrifolia, A. syriaca, A. sullvantii, A. purpurescens, A. hirtella, A. veridiflora); two species occur in Quebec (A. incarnata, A. syriaca); one species 1s recorded from New Brunswick (A. syriaca); and one species from Nova Scotia (A. incarnata).
From the above records of the distribution of species of the larval food plant and the direction of migration, it is obvious why there 1s by far the largest population in the northern range located in the province of Ontario.
SU)
Overnight Roosting Clusters
During the autumnal migration the Monarch Butterflies cluster on trees of various species along the migratory routes to remain during the night period (Urquhart 1960). Of the species of deciduous trees chosen Red Maple (Acer rub- rum), Sugar Maple (Acer saccharum), Mani- toba Maple (Acer negundo), and willow (Salix sp.) were most common. Pine (Pinus sp.) and spruce (Picea sp.) were most frequently chosen since it was possible for the butterflies to obtain a secure hold with the sickle-shaped tarsal claws (Urquhart 1960).
During periods of calm weather individuals of a cluster are widely spaced (Figure 1). During stormy conditions with strong winds the
migrants cluster closer together and there are fewer clusters on the trees. The massing together
URQUHART AND URQUHART: MONARCH BUTTERFLY 43
under conditions of strong winds has the distinct advantage of causing the weighted branch of the tree to sway in the wind rather than being whipped about, which would dislodge the migrants. The leeward side is always chosen as a protection against the wind.
Since migrants tend to cluster on certain trees year after year, it has been thought that perhaps an odor of some kind may have been left the previous year thus acting as a guide for future generations of migrants. Numerous observa- tions in many localities, however, have not produced evidence to substantiate such a sug- gestion. For example, when a particular group of roosting trees was removed, the migrants selected another group that had not been used previously. As has been demonstrated, the direction of migration, the presence of suitable
FIGURE |. Overnight roosting Monarch Butterflies during the autumnal migration showing the widely scattered nature of the
clusters.
44 THE CANADIAN FIELD-NATURALIST
trees en route located near nectar-producing flowers such as the Canada Goldenrod (Soli- dago canadensis) and the New England Aster (Aster novae-anglia), and topography are the factors determining the choice of roosting trees (Urquhart 1960).
Although overnight clusters may occur in numerous localities throughout southern On- tario, they are most abundant and composed of larger clusters along the north shores of Lake Ontario and Lake Erie. This is owing to the migrants’ antipathy to fly over large bodies of water beyond sight of land; hence they move in ever increasing numbers along the lake shores (Urquhart 1960, 1966, 1976a).
The manner in which the migrants cluster ona particular part of the roosting tree or trees is as follows. The first arrival flies around the tree, testing wind direction and a suitable site upon which to land. Many tests are made before a final location is chosen. Having finally landed the butterfly opens the wings to display the more brilliantly colored dorsal surfaces. This acts as a beacon to others that in turn land and open their wings. If one migrant lands too close to one already at rest the latter snaps its wings in a warning gesture which acts as a further stimulus for others to land upon the particular branch. Eventually a cluster is formed.
When the migrants reach their final over- wintering destination in the Neovolcanic Moun- tain site of Mexico (Urquhart 1976b; Urquhart and Urquhart 1977), they form dense clusters that are quite unlike those of the overnight roosts (Figure 2). Migrants on the overnight roosts, as mentioned previously, occur as small scattered clusters, the individuals widely spaced; they do not cluster on the trunks of the trees or upon adjacent bushes or upon the ground. Inthe overwintering clusters, the roosting trees are so densely covered that it is not possible to see the foliage of the trees; the trunks are also densely covered as well as the neighboring bushes. In some loci! the ground is also covered (Urquhart
'Site refers to the geographic location of an overwintering site, such as the Mexican Site, the California Site, etc.; Area refers toa particular geographic location where a number of clusters are to be found, such as a volcanic mountain in Mexico or the Monterey Peninsula in California; Locus (1) refers to a particular location within an area where a cluster exists which may change from year to year, suchas lociinan area in Mexico or in the Monterey Peninsula.
Vol. 93
and Urquhart 1977: Urquhart and Urquhart 1976a, b, d, 1977). This difference between the two clusterings is due to the massed millions of migrants in the overwintering roosts as com- pared to the smaller clusters scattered over a wide area along the migratory routes.
Migratory Routes
The Monarch Butterflies migrate from the breeding areas in Canada mainly to Mexico where they overwinter in various loci in various moun- tain areas of the Mexican Site in the Neovolcanic Mountains, sometimes referred to as the “Cross Range” (Urquhart and Urquhart 1979).
Migrants from west of Lake Superior move SSW (190°): those from the north shore of Lake Huron move SSW (200°) and those from extreme southwestern Ontario move SSW (215°) (Figure 3, route D). Migrants from the rest of Ontario and western Quebec indicate two flight patterns. The greater number move SSW (200°) to the coast of the Gulf of Mexico and thence westward (270°) (Figure 3, route C) following the Gulf coast eventually towards the overwintering site (Figure 3, route E) on a tra- jectory SSW (195°). Others, perhaps as a result of strong westerly winds during the flight period, move SSE (110°) (Figure 3, route A) to the Atlantic coast. Following the coast line SSW (195°-210°) the majority reach the coast of the Gulf of Mexico where, following the coast line, they travel westward (Figure 3, route C). Others, representing a small proportion of the migrating population, termed an “aberrant” population (Urquhart 1976a, b: Urquhart and Urquhart, 1976c, 1977), move down the Florida peninsula SSE (140°), thence to Cuba and Yucatan SSW (240°) (Figure 3, route B) or, continuing SSE (120°-140°) become scattered over the islands of the Antilles. The final destination of this aberrant population is as yet unknown.
Vernal Migration
Vernal migrants leave the Mexican Site in late February and March (Urquhart and Urquhart 1979). Mating takes place at the site, when the clusters break up, and along the migratory routes as far as central Texas — males rarely proceed further. They enter the various Cana- dian provinces, especially Ontario, commencing in the last week of May through June and early July. During late June and early July second-
1979 URQUHART AND URQUHART: MONARCH BUTTERFLY 45
FIGURE 2. Overwintering roosting Monarch Butterflies on a tree in the Neovolcanic Plateau Site of Mexico showing the compact nature of the clusters completely covering the branches and trunks of one of over a thousand trees.
46 THE CANADIAN FIELD-NATURALIST Vol. 93
FIGURE 3. Migration routes of the Monarch Butterfly from the breeding areas in Canada to the overwintering site in Mexico and the aberrant migration routes to Yucatan and the Antilles. @ breeding areas; * major overnight roosting areas; Aoverwintering site;—sdirection of flight. A, flight pattern to the Atlantic coast: B. flight pattern through Florida to Yucatan: C, flight pattern along the north coast of the Gulf of Mexico; D, flight pattern from the western provinces, north of Lake Huron and southwestern Ontario; E, overwintering Mexican Site; F, possible flight direction towards the Antilles.
1979
generation adults, resulting from eggs deposited on species of milkweed by migrating females, enter Canada. These are readily identified by their brighter coloration, those from the Mexi- can Site being decidedly faded with tattered wing margins (Urquhart 1966). First-generation adults from breeding areas in Canada appear from mid-July through August. A second generation occurs in the more southern sections from mid-August through September.
Autumnal migration commences in mid- August, the numbers increasing through late August and September and, under conditions of high temperature, through October. A few stragglers have been collected in November and three specimens during the first week of Decem- ber. It is highly unlikely that these late migrants reach the overwintering sites.
Acknowledgments
Financial support for the studies of the biology of the Monarch Butterfly has been received from the National Research Council of Canada; the National Geographic Society, Committee for Research and Exploration; and the Insect Migration Association.
Literature Cited
Urquhart, F. A. 1941. A proposed method for marking migrant butterflies. Canadian Entomologist 1941 (February): 21-22.
Urquhart, F. A. 1960. The Monarch Butterfly. University of Toronto Press, Toronto. 361 pp.
Urquhart, F.A. 1965. Monarch Butterfly (Danaus plexippus) migration studies: autumnal movement.
URQUHART AND URQUHART: MONARCH BUTTERFLY 47
Proceedings of the Entomological Society of Ontario 5: 23-33.
Urquhart, F. A. 1966. A study of the migration of the Gulf Coast populations of the Monarch Butterfly (Danaus plexippus L.) in North America. Annales Zoologici Fennici 3: 82-87.
Urquhart, F. A. 1976a. Migration of butterflies along the gulf coast of northern Florida. Journal of the Lepidop- terists’ Society 30: 59-61.
Urquhart, F. A. 1976b. Found at last: the monarch’s winter home. National Geographic Magazine 150: 161-173.
Urquhart, F. A. and N.R. Urquhart. 1976a. Monarch Butterfly (Danaus p. plexippus L.) overwintering popula- tion in Mexico (Lepidoptera: Danaidae). Atalanta 7: 56-60.
Urquhart, F. A. and N.R. Urquhart. 1976b. Ecological studies of the Monarch Butterfly (Danaus p. plexippus L.). National Geographic Society Research Report 1976: 437-443.
Urquhart, F. A. and N.R. Urquhart. 1976c. A study of peninsular Florida populations of the Monarch Butterfly (Danaus p. plexippus L.; Danaidae). Journal of the Lepidopterists’ Society 30: 73-87.
Urquhart, F. A. and N.R. Urquhart. 1976d. The over- wintering site of the eastern population of the Monarch Butterly (Danaus p. plexippus L., Danaidae) in southern Mexico. Journal of the Lepidopterists’ Society 30: 153-158.
Urquhart, F. A. and N. R. Urquhart. 1977. Overwintering areas and migratory routes of the Monarch Butterfly (Danaus p. plexippus; Lepidoptera: Danaidae) in North America, with special reference to the western popula- tion. Canadian Entomologist 109: 1583-1589.
Urquhart, F. A. and N. R. Urquhart. 1979. Vernal migra- tion of the Monarch Butterfly (Danaus p. plexippus L.; Lepidoptera: Danaidae) in North America from the overwintering site in the neovolcanic plateau of Mexico. Canadian Entomologist (In press).
Received 25 May 1978 Accepted 14 August 1978
Reproductive Biology of the Big Brown Bat (Eptesicus fuscus) in Alberta
DAVID B. SCHOWALTER and JOHN R. GUNSON
Alberta Fish and Wildlife Division, 6909-116 St., Edmonton, Alberta T6H 4P2
Schowalter, D. B. and J. R. Gunson. 1979. Reproductive biology of the Big Brown Bat (Eptesicus fuscus) in Alberta.
Canadian Field-Naturalist 93(1): 48-54.
Data on Big Brown Bat (Eptesicus fuscus) populations in Alberta were collected from 1972 to 1977 during surveys to determine the prevalence of rabies. The 60 maternity colonies located included 56 in older buildings; many of these sites were used as hibernacula. Most young were born during the latter part of June; parturition was estimated to extend from at least 5 June to 12 July. Fifteen of 115 pregnancies were twins. Ages of a sample of bats were determined by counts of dental annuli; those ages generally correlated with tooth wear. Yearling females had a lower pregnancy rate than older females.
Key Words: Big Brown Bat, life history, dental aging, Alberta.
The Big Brown Bat (Eptesicus fuscus) 1s relatively abundant and widely distributed over North America (Hall and Kelson 1959; Barbour and Davis 1969). Most studies of the species have been in eastern North America (Christian 1956; Brenner 1968; Davis et al. 1968; Barbour and Davis 1969; Kunz 1974; Mills et al. 1975) where the usual litter size is two. Comparatively few data are available for the species in western North America, particularly western Canada, where the usual litter size is evidently one (Cockrum 1955; Christian 1956; Kunz 1974).
A bat-rabies monitoring program in Alberta was prompted by the first diagnosis of a rabid bat in the province in 1971, and an outbreak of rabies among other animals in 1970 and 1971. Epidemiological results of this program have recently been presented by Dorward et al. (1977); biological data on Ef. pallidus in Alberta collected during the course of the study are presented here.
Methods
Colonies were located through the following means: complaints of bats relayed by govern- mental personnel and systematic surveys during 1971 to 1977; newspaper advertisements in 1971 and 1972; results of a questionnaire mailed to rural homeowners in 1973; and reviews of histories of rabies-suspect bats. Collections of 10 to 20 bats for rabies testing were made at a number of maternity roosts; larger collections
48
were made at two maternity roosts and a fall roost, all of which were known to have harbored rabid individuals. Bats were collected within colonies by hand, forceps, and a modified Constantine trap (Constantine 1958); at colony exits by a variety of enclosure traps; and by mist-nesting away from colonies. Colonies were generally visited only once, although two or three visits per year were made to one colony to band bats. Available for analysis were 256 Big Brown Bats submitted as rabies-suspect indi- viduals from 1974 to 1977.
Age (adult or juvenile) as determined by closure of the epiphyses of the fingers, and sex were noted for each bat. Reproductive status of adult females was recorded, as was the number and sex of fetuses of parous individuals. Ages of adult bats taken at two maternity roosts, a fall roost, and a sample of rabies-suspect individuals were determined from counts of dental annuli (Schowalter et al. 1978). The first of January was arbitrarily used as the date on which bats became a year older: thus a bat classified as a l-yr-old was taken the summer after the summer of its birth. Tests for significance were by the simple chi-square test.
Results and Discussion
Big Brown Bats appeared to be more abun- dant in southern than central Alberta (Figure 1). We discovered 32 colonies in southern Alberta and 28 colonies in the larger area of central
1979
HINTON Colony Size
@® 1-25
@ 26-250
ee Over 250
(0) 50 100 Km +4
FIGURE |. Distribution of known
Alberta. Although estimates of the number of bats were approximate, colonies were evidently larger in the south, where the average number of adults was 80. In central Alberta average colony size was 44. Mist-net captures indicated that Big Brown Bats were relatively abundant in natural habitats along river valleys in the southern area of the province. Much of this apparent greater abundance in the south is related to the occurrence of maternity roosts in the cities of Medicine Hat and Lethbridge. We have seldom located maternity roosts of Big Brown Bats, or other species, in more northerly cities in Alberta. A search of 28 old buildings in Edmonton, mostly schools, which were similar to buildings
SCHOWALTER AND GUNSON: BIG BROWN BAT, ALBERTA 49
-— _—_— — = aw = =, =-
EOMONTON a e e
C ) S O CAMROSE e @ ° @ @ e® ® e @ g RK) CALGARY
Big Brown Bat colonies in Alberta.
frequently colonized in Medicine Hat and Lethbridge, produced no evidence of active maternity colonies.
A strong preference was evident for the formation of maternity colonies in older build- ings; 56 of 60 buildings with Big Brown Bat maternity colonies were built prior to 1925. Banding studies (Beer 1955; Davis et al. 1968; Barbour and Davis 1969) have demonstrated strong site attachment of Big Brown Bats. Failure to colonize newer buildings may in- dicate a decreased or stable population that is strongly attached to roosts currently in use. Alternatively the variable environment in older buildings may meet the physiological needs of
50 THE CANADIAN FIELD-NATURALIST
the bats better, by permitting both summer and winter roosting. Many nurseries were evidently utilized as hibernacula by at least a few (and often many) bats in Alberta, as noted by others (Mills et al. 1975; Hitchcock 1949). Environ- mental conditions in newer buildings are likely to be different as a result of recent changes in heating systems and insulation standards.
Big Brown Bat roosts were similar to those described elsewhere (Barbour and Davis 1969; Mills et al. 1975); those we observed were generally cooler than Little Brown Bat (Myotis lucifugus) maternity roosts inspected. Big Brown Bats were extremely tolerant of light in some roosts.
Many owners of the buildings that were used as maternity roosts by Big Brown Bats believed that bats were resident during the winter, although only 19 reported having seen bats in this period. Other buildings, particularly in the city of Edmonton, that were not maternity roosts were utilized by wintering bats. Our winter captures of Big Brown Bats, and citizen submissions of bats for rabies testing from Edmonton, far exceeded those of summer. On the other hand, numerous summer submissions were made of Little Brown Bats and a few Silver- haired Bats (Lasionycteris noctivagans) (Dor- ward et al. 1977; this study, unpublished data). These observations suggest that Big Brown Bats moved into Edmonton to hibernate.
Five buildings in Edmonton and one non- maternity roost building in Camrose and Hinton regularly were occupied by bats in winter. As many as six bats captured in one winter at two of these sites were known to us; however, it is unlikely that most bats encountered in these buildings were reported. Winter occurrences were frequently associated with the onset of cold weather. In addition Big Brown Bats have been discovered during the course of building demoli- tion and remodelling; and in one case, loud rock bands in a high school gymnasium were con- sidered almost certain to cause bat activity.
As noted by Barbour and Davis (1969) E. fuscus is extremely cold-tolerant. Two indi- viduals were captured outside a building on 3 December 1975. Temperature at time of capture was near —15°C, and had been even lower earlier in the day. One bat was alert and shivering; the other was torpid, but quickly became active
Vol. 93
when warmed. The bats had roosted near a recently filled crack and may have been attempt- ing to enter the building.
Timing of events at maternity roosts was difficult to define as visits were made ir- regularly. It was evident, however, that there was variation between colonies, and probably be- tween years. Bats were active at one location, which was thought to be a hibernaculum as well, on 8 April 1976 and 13 April 1977. The nature of bat activity at these times was unknown as the apparent food supply was extremely limited. One maternity site was determined to be without bats as late as 10 May 1977.
Roosting in four types of groups (pregnant females, females with naked young, furred young, and lactating females) was observed in one maternity roost. Similar separate roosting, although usually in only two or three types of groups, was noted in other colonies. This grouping created uncertainty as to the timing of parturition, as generally not all the bats in a roost were known to have been observed. These groupings were thought to be related to differ- ing thermal requirements of individuals at different stages of reproduction and growth.
Time of parturition varied considerably both in, and between, colonies. Fetal examination and observation of neonates indicated that most young were born in the latter part of June. The earliest estimated birth date was 5 June. Near- term pregnant females were taken as late as 12 July.
Of 114 adult females taken from maternity roosts during late May and early June, 105 were pregnant. Of 115 bats examined in advanced pregnancy, 15 had twins, which corroborates Christian’s (1956) finding that one is the usual litter size in western North America. Sixty-two of 84 single young had implanted in the right horn of the uterus. Kunz (1974) also noted a tendency towards implantation in the right horn. Fetal sex ratio was near 50:50 (Table 1).
During 1974 and 1975 significantly more adult females (P< 0.05) than adult males were sub- mitted for rabies testing (Table 1). During these two years public concern about bat rabies was high; more than 400 bats were submitted per year. It appeared that many normal-acting bats were submitted as rabies suspects from mater- nity roosts. Most bats submitted in 1976 and
1979
SCHOWALTER AND GUNSON: BIG BROWN BAT, ALBERTA 5]
TABLE |—Age-specific sex ratio in samples of Epresicus fuscus from Alberta, 1972 to 1977
Sample Adults Juveniles Fetuses No. % Male No. % Male No. % Male
Colony survey
20 May-31 July 261 3.1 100 45.0 73 S23
1 Aug-30 Sept 69 23.2 79 26.6
Rabies suspect
1974-1975 107 36.4 46 60.9
1976-1977 58 S522 45 71.1
1977, when approximately 200 bats a year were submitted, were either grounded or found in other atypical situations. In those two years the numbers of adult males and females submitted were similar (Table 1).
Juvenile males tended to leave colonies earlier than juvenile females during late July and August. They occurred significantly less fre- quently (P< 0.01) than juvenile females in our samples from buildings during August and September (Table 1). This earlier departure may have subjected them to higher mortality, as they were submitted for rabies testing more frequently (P< 0.05) than juvenile females (Table 1).
Results of dental aging (Figure 2) indicated a life-expectancy similar to that found by Goeh- ring (1972) from a 20-yr banding study in a Minnesota hibernaculum. Our samples varied in age structure, particularly in the proportion of I- yr-old bats (Figure 2). One-year-olds constituted 39% of the rabies-suspect sample; the sample was comprised of bats from the greatest variety of situations and capture dates, and may be the most representative of the population age structure. It is, however, made up of bats that died from natural or human causes. One-year- old females from maternity colonies made up only 16% of the sample (Figure 2). That only 15 of 31 l-yr-old rabies-suspect and survey females were parous or had suckled young demonstrated that many lI-yr-old females are non-parous as noted by Christian (1956) and Barbour and Davis (1969). Non-parous 1|-yr-old females may tend not to roost in maternity colonies and may be more likely to be submitted as rabies-suspect bats than older females.
Ages of bats from Connaught School (Figure 2) have been discussed by Schowalter et al.
(1978). Younger animals appeared to be under- represented in that sample compared to the other samples and what would be expected from banding results (Goehring 1972). Estimates of the total number of adults in the Connaught colony in June ranged from 500 to 1000, comparable to the largest colonies noted by Mills et al. (1975). Those authors determined that there was an unknown density-dependent mechanism functioning to regulate populations in large colonies. The relatively small number of individuals in some of the younger age-groups in the Connaught sample suggests low survival of young or that a large proportion of juvenile females disperse from the colony prior to their second year. The pregnancy rate of adult females from Connaught, 45 of 51, while less than that of females from other colonies (P< 0.05), is not low enough to suggest that the regulatory mechanism operates primarily through limiting reproduction.
Tooth wear has been considered as a means of aging bats (Twente 1955; Christian 1956; Stege- man 1956). Mills et al. (1975) found a highly: significant relationship between tooth wear and ages of 208 Big Brown Bats banded as im- matures. They observed wide variation in wear rates of individual bats. One of us (JRG) recorded tooth wear of bats in the Connaught School sample. Although analysis was limited by the subjective nature of the estimates of tooth wear and the possibility of errors in aging by annuli, there was general agreement between the two methods (Figure 3). Tooth wear would appear to be potentially useful as a method of determining relative population-age structures of Big Brown Bats in Alberta.
The possibility of a population decline and the factors governing the growth and size of colonies
S52 THE CANADIAN FIELD-NATURALIST Vol. 93
Connaught School
Maternity Sample n=51
Stony Plain Maternity Sample
White Elephant Fall sample =43
Percent of Sample
Rabies Suspect n= 49
12 Si waa eal 7emoie > elOm lal l2ilS ue lAghlow Onl Zale Age Group
FIGURE 2. Distribution of ages of samples of Big Brown Bats from Alberta (determined by counts of dental annuli). Specimens from Connaught School, Medicine Hat; Stony Plain; and White Elephant Theatre, Bow Island. Numerals at base of bars indicate number of bats.
1979
—~-~NWAU—NWEUNUAN DWDODO,H NW EN AN © DO O
Number of Bats
EF] EI = eo es
SCHOWALTER AND GUNSON: BIG BROWN BAT, ALBERTA 53
Light wear n=19 x=2.9
Moderate wear n= 19 x= 5.8
Heavy wear n= 13 x= 9.)
De Si Ae Ol 72a, LOnill 2) 1S 42 lo Onl7a18" 19-20,
Dental Age Group
FIGURE 3. Comparison of amount of tooth wear and ages, as determined by counts of dental annuli, of Big Brown Bats
from Connaught School.
in central and southern Alberta need further investigation. Dental aging appears to offer a powerful tool in such investigations, although this technique requires further evaluation.
Acknowledgments
The interest and support of H. Vance and G. Whenham of the Veterinary Services Division, Alberta Department of Agriculture are greatly appreciated. The Agriculture Canada Animal Diseases Research Institute (Western) at Leth- bridge, Alberta has provided continued co- operation in allowing access to specimens and records of rabies-suspect animals; W. Dorward,
J. Bradley, H. Boumans, B. Prins, and D. Meyers of that institution contributed in various ways to this study. Field and laboratory assis- tance were provided by L. Harder, B. Treichel, L. Dube, P. Cole, W. Johnson, and W. Wynnyk. N. Previsich contributed generously of his time and energy. We thank A. Todd and L. Harder for comments on an earlier draft.
Literature Cited
Barbour, R. W. and W. H. Davis. 1969. Bats of America. University Press of Kentucky, Lexington. 286 pp.
Brenner, F. J. 1968. A three-year study of two breeding colonies of the Big Brown Bat, Eptesicus fuscus. Journal of Mammalogy 49: 775-778.
54 THE CANADIAN FIELD-NATURALIST
Beer, J. R. 1955. Survival and movements of banded Big Brown Bats. Journal of Mammalogy 36: 242-248.
Christian, J.J. 1956. The natural history of a summer aggregation of the Big Brown Bat, Eptesicus fuscus fuscus. American Midland Naturalist 55: 66-95.
Cockrum, E. L. 1955. Reproduction of North American bats. Transactions of the Kansas Academy of Sciences 58: 487-511.
Constantine, D. G. 1958. An automatic bat-collecting de- vice. Journal of Wildlife Management 22: 17-22.
Davis, W. H., R. W. Barbour, and M.D. Hassell. 1968. Colonial behavior of Eptesicus fuscus. Journal of Mam- malogy 49: 44-50.
Dorward, W.J., D.B. Schowalter, and J. R. Gunson. 1977. Prelimary studies of bat rabies in Alberta. Can- adian Veterinary Journal 18: 341-348.
Goehring, H.H. 1972. Twenty-year study of Eptesicus fuscus in Minnesota. Journal of Mammalogy 53: 201- 207.
Hall, E.R. and K.R. Kelson. 1959. The mammals of North America. Volume |. Ronald Press, New York. 546 pp.
Vol. 93
Hitchcock, H. B. 1949. Hibernation of bats in southeastern Ontario and adjacent Quebec. Canadian Field-Naturalist 63: 47-59.
Kunz, T. H. 1974. Reproduction, growth and mortality of the vespertilionid bat Eptesicus fuscus in Kansas. Journal of Mammalogy 55: 1-13.
Mills, R. S., G. W. Barrett, and M. P. Farrell. 1975. Pop- ulation dynamics of the Big Brown Bat ( Eptesicus fuscus) in southwestern Ohio. Journal of Mammalogy 56: 591— 604.
Schowalter, D. B., L. D. Harder, and B. H. Treichel. 1978. Age composition of some vespertilionid bats as deter- mined by dental annuli. Canadian Journal of Zoology 56: 355-358.
Stegeman, L. C. 1956. Tooth development and wear in Myotis. Journal of Mammalogy 37: 58-63.
Twente, J. W., Jr. 1955. Aspects of population study of cave-dwelling bats. Journal of Mammalogy 36: 379-390.
Received 14 June 1978 Accepted 18 September 1978
Wild Mallard Stocking in a Large Marsh Habitat
ROBERT O. BAILEY
Macdonald College of McGill University, Ste. Anne de Bellevue, Québec
HOA !CO
Bailey, R.O. 1979. Wild Mallard stocking in a large marsh habitat. Canadian Field-Naturalist 93(1): 55-62.
During 1971 and 1972, 1204 female and 214 male wild-strain Mallard (Anas platyrhynchos) ducklings were released on the Delta Marsh to test Mallard stocking as a method to increase breeding populations. Hand-reared yearling hens arrived after most of the unmarked hens in spring. Homing to the release site was observed in 26-28% of yearling hens and 53% of 2-yr-olds. Yearling marked hens initiated nests later and were less successful than unmarked hens in producing broods. Differences between the marked yearlings and unmarked breeders were attributed to the presence of the adult hens in the unmarked portion of the breeding population. In view of the poor reproductive success of hand-reared birds and apparently high potential for natural immigration and production, Mallard stocking is a questionable procedure on the Delta Marsh.
Key Words: Mallard, stocking, spring arrival, homing, nest initiation, productivity, breeding success.
Early propagation efforts involved mainly the release of semi-domestic strains of Mallard (Anas platyrhynchos) ducklings. Lincoln (1934), Errington and Albert (1936), Benson (1939), Foley (1954), Hunt et al. (1958), and Schlad weiler and Tester (1972) concluded that releases of game farm birds were generally unsuccessful, because of the inability of these birds to survive and reproduce in the wild, and because they were extremely vulnerable to hunting. Stocking pro- grams using wild-strain birds, however, have been successful in establishing Mallards (Foley et al. 1961; Lee and Kruse 1973) and Wood Ducks (Aix sponsa) (Doty and Kruse 1972) on vacant or understocked habitat.
In 1969 the Delta Waterfowl Research Station began to study the potential of releasing hand- reared wild Mallard ducklings to increase local breeding populations. Sellers (1973) made sev- eral releases into pothole habitat near Minne- dosa, Manitoba, and the breeding population increased from 12 pairs in 1969 to 66 pairs in 1971 on his 2.56-km2 study area. But only 9% of the homing (marked, hand-reared) females at Minnedosa produced broods in 1971. Sellers attributed poor production to severe nest preda- tion associated with a lack of nesting cover. Upland nesting cover had been removed by agricultural tilling and burning. Based on those findings, the present study was initiated in 1971 on the Delta Marsh, where agricultural land use is negligible and nesting cover appeared ade- quate.
The objective of this study was to determine whether hand-reared Mallards would home to a specific release site in the Delta Marsh and, if so, would reproduce at a level to maintain their numbers. When it became evident in 1972 that yearling hens were not producing broods, the emphasis of the study was changed to a comparison of productivity in hand-reared and wild Mallards on the same areas.
Study Area
The Delta Marsh is a 140-km?2 expanse of shallow bays, creeks, and potholes at the south end of Lake Manitoba (Figure 1). The north edge of the marsh is separated from the lake bya sandy wooded ridge. Dense stands of Yellow Cane (Phragmites australis) interspersed with patches of White-top (Scolochloa festucacea) meadow cover most of the dry surface from the ridge to the bay edges. Cattail (Typha /atifolia) grows in dense stands around potholes, creeks, and on flooded bay shorelines. Bulrush (Scirpus spp.) is common in large shallow bays. Addi- tional description of topography, climate, and vegetation is given by Bird (1961, p. 19), Love and Love (1954), and Anderson and Jones (1976).
In 1971 duckling releases were made at the Diversion, 4.8 km W of the village of Delta. This study area is 2.56 km? in size, divided by the Assiniboine River Diversion. Creeks, potholes, and borrow pits are typical wetlands on the area.
In 1972 an additional release site was estab-
56 THE CANADIAN FIELD-NATURALIST
ASSINIBOINE
Voles93
STUDY AREAS | DIVERSION
2 AIKENS BAY
3 COOKS CREEK
@PAIRS OF YELLOW SADDLED MALLARDS 1 KM +—4
FiGure |. Map of the Delta Marsh illustrating the study areas and the location of marked females established outside the
release sites in 1973.
lished at Aikens Bay, a 0.8-km? area, 8 km E of Delta. The aquatic and upland habitat at Aikens Bay was managed for waterfowl (mainly by water-level regulation) and was considered to be high quality. An unknown number of wild Mallards occupied each release site prior to stocking.
A 2.56-km? area at Cooks Creek Meadow, 4.8 km E of Delta, was chosen for a control (1.e., no birds released) in 1972. That area is typical marsh habitat.
In 1973 water levels were lower than usual on parts of the Delta Marsh. Wind tides from Lake Manitoba maintained water levels in the larger bays, but lack of precipitation left many nearby potholes and shallow marshes dry. Precipitation at Portage la Prairie was 7.62 cm lower than the long-term mean for 6 mo prior to 30 March 1973 (Atmospheric Environment Monthly Reports).
Methods
Ducklings were hatched 1n an incubator, from eggs taken from a captive flock originating from eggs gathered in the wild and hatched at Delta. Ducklings were hand-reared (Ward and Batt
1973) until 4-5 wk of age before release. Each duckling was fitted with an individually num- bered plastic nasal saddle and a standard U.S. Fish and Wildlife Service leg band immediately prior to release. Birds were liberated in groups of 10-15 throughout all wetlands on the study areas.
In 1971, 456 females and 180 males were released at the Diversion. In 1972, 503 females and 34 males were liberated at Aikens Bay and 245 females at the Diversion site.
Mallard breeding densities were estimated by checking on foot each wetland on the study area. Each Mallard observed was checked for a nasal saddle. Counts were conducted as suggested by Dzubin (1969). A 12.87-km roadside transect was run 5-6 times a week on the Diversion and surrounding area each year and several walking transects were conducted at Aikens Bay. These transects provided information on the ratio of marked to unmarked females, homing hens, and the male:pair ratio. The ratio of marked to unmarked females was used to obtain an estimate of marked hens represented by drakes.
Sex ratio of Mallards counted prior to 15
1979
April was applied to lone males and groups of five or less to correct breeding pair estimates for the unmated drake cohort. I assumed that all Mallards present were counted during each census.
Several square kilometres of marsh sur- rounding the study areas were searched each year for marked birds. Locations of marked hens were plotted on a map and revisited until the hen was identified or had disappeared.
In 1973, nest searches were carried out 2-3 times a week between 09:00 and 12:00 from the second week of April to the beginning of July. Two observers and a Labrador retriever partici- pated in each search. Nests were located, plotted on a map, and marked witha piece of fluorescent tape on vegetation or a stake 3-4 m away. Nest initiation date was estimated for each nest by back-dating eggs in incomplete clutches (Dane 1966). Eggs in nests containing down were floated (Westerskov 1950) to estimate the ap- proximate stage of’ incubation. Nests were revisited after the anticipated hatching date and nests containing finely crushed egg-shells and membranes were considered hatched.
Brood searches consisted of walking the emergents surrounding wetlands. The number and age of young (in weeks) and the marking, if any, on the female were used to avoid duplica- tion in counts. This technique was supplemented with morning and evening road transects, walking transects, and observation periods wherein one block of habitat was observed for 2-3 h. Broods in Aikens Bay were observed from a 6-m tower in a central location on the site.
In spring 1973, 15 paired Mallard females were collected on the marsh, at least 2 km away from the study areas, in an attempt to estimate the proportion of adults in the unmarked population. Only females from isolated pairs were shot. Hens were qualitatively classed as yearling or adult based on examination of wing feathers (Carney and Geis 1960; Hopper and Funk 1970). Wings from known adults were examined for comparison.
Results Spring Arrival and Breeding Densities
The first Mallards (six) in 1972 arrived on the Diversion on 7 April, and did not include any
BAILEY: WILD MALLARD STOCKING 57
TABLE I—Mallard breeding pair counts (with 95% con- fidence intervals) on the Diversion and Aikens Bay, Delta, Manitoba. Pairs are corrected for sex ratio.
Pairs Study area 1971 1972 Total released released unmarked Diversion 5 May 1972 7 ae 7/ — 1947 36 17 May 1972 19+5 = 6} a8 5) ay Means 18.0 13.5 32 1 May 1973 644 9+4 1145 26 17 May 1973 9+5 10+6 WD) ae 7/ 30 Means ES 9.5 LES 28 Aikens Bay 26 April 1973 —— 1444 il ae 5 35 8 May 1973 — 1344 9+5 22 Means 13.5 15.0 29
marked hens. On 13 April the first marked female and her mate were observed in a flock of five pairs on the study area. Most of the marked Mallards did not arrive until the week starting 21 April, when the mean number of marked hens observed per road transect increased to 3.85 from 0.58 the previous week. Over the same time period the mean number of unmarked hens observed per road transect decreased from 17.4 to 10.6.
Spring 1973 was phenologically very early, and the first Mallards arrived at Delta on 21 March. On 27 Marcha marked yearling hen was seen at Aikens Bay (Peter Ward, personal communication). When I arrived on 12 April, all hens were back.
The breeding pair censuses (Table 1!) were timed to correspond with Mallard nest initiation dates as indicated by increases in the male: pair ratio along roadside transects. Prior to 15 April 1972, 496 Mallards were seen with a sex ratio of 57.3 males to 42.7 females. Prior to 15 April 1973, 543 Mallards showed a sex ratio of 54.7 males to 45.3 females.
Mallard breeding pairs on the Diversion averaged 32 per 2.56 km? in 1972 and 28 in 1973 (Table 1). Aikens Bay contained 29 pairs of Mallards (93 pairs per 2.56 km?2). Surveys commencing 14 and 21 May 1973, on Cooks Creek Meadow revealed a population of 54 and 55 pairs of Mallards per 2.56 km? respectively.
58 THE CANADIAN FIELD-NATURALIST
Homing of Mallards Released in 1971 and 1972
High pre-fledging mortality of an unknown number of ducklings in 1971 severely limited the number of hens alive to return in 1972 (Bailey, unpublished data). In all, 28 females were individually identified on the Diversion in 1972 (see below for number that actually settled on the area). All homing females were accompanied by unmarked drakes and no marked males were observed. Extensive searches of the surrounding marsh did not reveal additional marked birds.
Breeding pair counts indicated that about eight 1971-released birds returned to the Diver- sion in 1973, (Table 1). It was not possible to recognize individually all 2-yr-old females in 1973 because the paint had worn off many saddles. Assuming a 52% annual survival rate for adult females in southwestern Manitoba (Anderson 1975) and considering that 28 hens returned to the Diversion in 1972, then the eight birds observed in 1973 represented a homing rate of 53% for 2-yr-old females. This adult homing rate is considered minimal since the Delta Marsh is a major Mallard harvest area within south- western Manitoba.
In 1973, 17 hens released in 1972 were identified on the Diversion (see below for number that settled). Marked hens from 1972 releases there appeared to have homed solely to the release site, because they were not found elsewhere in the marsh.
Females homing to Aikens Bay encountered high densities of marked and unmarked Mal- lards (Table 1). At Aikens Bay, 14 returning marked hens and | unmated marked male were identified. An additional 17 marked hens were observed scattered widely throughout the marsh E of Delta and W of Clandeboye Bay (Figure 1). Numerous marked females from Aikens Bay releases only established themselves on the lakeshore opposite Aikens Bay. Another marked male was observed with an unmarked hen at Marshy Point, 30.4km E of Delta (Robert Blohm, personal communication).
I estimated that 186 of the females released at the Diversion and 366 females in Aikens Bay fledged in 1972. Robert Jones (personal com- munication) calculated that the first-year mor- tality rate of hand-reared Mallards released at Delta between 1954 and 1970 was 67.2%. To
Vol. 93
calculate homing rate I assumed this mortality rate for first-year fledged females in this study. The 17 returning hens at the Diversion in 1973 represented 28% of the possible yearling sur- vivors. There was a 26% homing rate (n = 31) of marked yearling hens returning to Aikens Bay and the east marsh in 1973.
Comparison of Breeding Pair Counts and Homing Individuals
There was a discrepancy between the number of identified yearlings homing to the Diversion and the corresponding breeding pair estimates (28 identified homing in 1972 vs. pair estimate of 18; and in 1973, 17 identified homing vs. pair estimate of 9.5). This suggested that many homing marked hens were missed during the census or a certain proportion of marked yearlings visited the study area only briefly each year. In 1972, 13 (46%) of 28 homing hens were identified only once during 51 roadside transects on the Diversion whereas the remainder (15) were recognized an average of 4.7 times each. The mean residency bout for females sighted more than once was 32 d in 1972, as determined by the number of days between the first and last sighting. In 1973, 7 (41%) of 17 hens were seen only once during 53 transects and the remainder (10) recognized an average of 2.5 times. The mean residency bout was 31.3 d in 1973.
Nest Initiation and Productivity
Two of the earliest nests of unmarked hens were back-dated to 16 and 20 April 1973, whereas the earliest marked females (two) began nesting on I5 May. A second peak of nest initiation by unmarked hens occurred from 27 May to 2 June (Figure 2), and was apparently due to renesting and initial nesting by Mallards moving into newly-formed water areas after 3.2cm of precipitation received during this period. A larger proportion of unmarked hens than of marked yearlings had started nesting prior to 15 May (x° = 4.8, P< 0.05, n = 36).
Generally poor reproductive success was recorded for released birds nesting as yearlings. Nest predators, chiefly Striped Skunks (Mephi- tis mephitis), Raccoons (Procyon lotor), and Red Foxes (Vulpes vulpes), were common on both study areas and accounted for most nest failures (Table 2). No marked Mallard hens with broods were discovered on the Diversion in
1979
PERCENT OF TOTAL NESTS INITIATED = I) Os £ i) o Oo (e) Oo eo) eo) Oo
Oo
IS 2l
| APRIL | MAY
M= MARKED YEARLINGS n:=!! Ml UNMARKED MALLARDS n= 24
MR
28% 9.7 12
BAILEY: WILD MALLARD STOCKING 59
Pi biba
19°26. 25° 79 | JUNE
I6 23
FIGURE 2. Distribution of nest initiation dates for marked vearlings and unmarked Mallards on the Delta Marsh study areas,
1973.
1972. In 1973, one brood of five ducklings was found with a 1972-released hen; however, no broods led by 1971-released hens were observed. Two marked hens with broods were found at Aikens Bay and two more marked hens with broods were located in the vicinity of the release site. One marked hen with a brood was observed on Cooks Creek, 1.6 km S of Aikens Bay.
Mallard breeding pair counts for the Diversion and Aikens Bay indicated that the ratio of marked yearling hens to unmarked females (41:40) was approximately I to I each year. Significantly more broods accompanied by unmarked hens (P = 0.005, binomial test, Siegel ° 1956), however, were discovered on the release sites.
TABLE 2—Nest success records for Mallards and other dabblers, Delta Marsh, 1973
Year Hatched Not of
Species release Nests No. OK Destroved revisited! Deserted Mallard
marked 1972 1] 2 20 8 | 0
marked 1971 3 0 0 3 - 0
unmarked 28 1] 42 IS) 2 0 Other
dabblers 81 23 36 32 19 7
'Not included in the calculation of the percentage of nests hatched.
60 THE CANADIAN FIELD-NATURALIST
Vol. 93
TABLE 3—Percentage of marked and unmarked Mallard pairs producing broods at the Diversion and Aikens Bay in
1972 and 1973 1972 1973 Study area Year of Number of Percentage Number of Percentage release breeding pairs producing broods breeding pairs producing broods Diversion 1971 18.0 0.0 V3 0.0 1972 _— —_ QS 10.5 unmarked IBES 22. 15) 34.3 Aikens Bay 1972 _ — 13.5 14.8 unmarked — a 15.0 50.0 Fourteen nests of marked Mallards were Discussion
discovered during nest searches conducted in 1973 (Table 2). Eleven of these were nests of yearling hens, and three were initiated by 2-yr- old hens at the Diversion. Two of the 11 yearling nests hatched, 8 were destroyed by predators and 1 was not relocated. All three nests of 2-yr-old hens were destroyed.
Nesting success was 20% (n= 10) for nests initiated by marked yearling Mallards, whereas unmarked Mallard hens hatched 42% (n = 26) of nests initiated (no significant difference (P = 0.150) using a Fisher exact probability test (Siegel 1956)). The low probability obtained, however, suggests that the number of yearling nests found may not constitute a large enough sample to show a real difference, especially when a substantial proportion (see below) of the unmarked population was also yearling hens. When the combined nesting success of I- and 2- yr-old marked hens was compared with nesting success of unmarked hens, the Fisher exact probability decreased to 0.070. Nesting success of other dabblers encountered during nest searches was 36% (n = 81).
Fifteen paired Mallard females were shot in spring 1973. These females included nine adults and six yearlings, based on wing-feather exami- nation. Evidently there was a large proportion of adult females in the unmarked Mallard popula- tion.
The percentage of unmarked hens producing broods was much higher than that of marked hens on each study area in both years (Table 3). During the 2-yr study, 76 Mallard hens were identified as first-year breeders; of these, only 6 hens (8%) were observed with broods on orinthe vicinity of the release sites.
Most of the marked yearlings arrived well after the majority of unmarked hens. Spring arrival of hand-reared yearlings may extend over several weeks. Sellers (1973) concluded that yearling marked hens did not lag behind adults, based on the appearance of marked birds with the first arrivals in his area; however, he did not determine when the majority of marked year- lings arrived in relation to adults.
Wild-strain hand-reared Mallard females were able to return to specific release sites within the marsh. High pre-fledging mortality of 1971 releases did not prevent some survivors from returning to the study area in spring 1972. Homing of 53% (estimated) of surviving 2-yr-old hens to the Diversion showed that nesting failure during the previous year was probably not a deterrent to homing in subsequent years. A high percentage of adult hens homed in spite of low water levels in 1973.
Lower homing rates of yearlings compared to those of adults have been reported for Mallard, Gadwall (A. strepera), Pintail (A. acuta), Blue- winged Teal (A. discors) (Sowls 1955); Wood Duck (Bellrose et al. 1964); Shoveler (A. clypeata), (Poston 1974); and Tufted Duck (A. fuligula) (Mihelsons et al. 1970). The pro- portion of yearling marked Mallards homing was approximately one-half that of marked adults. Furthermore, only about 60% of homing yearling hens resided on the area for extended periods each nesting season. The remainder were sighted only once, usually prior to nest initiation or after nesting in July. These observations support the contention of Hochbaum (1955, p. 124) that some hens may home to their natal area but then move elsewhere to nest. On 29 July
1979
1973, a flightless, 1972-released Mallard was observed 0.8km S of Aikens Bay, so an unknown proportion of marked hens also used the marsh to molt.
Males did not generally home to release sites. In Mallards, pairing usually takes place on the wintering grounds and males follow their mates back to their natal area (Sowls 1955). But the appearance of one homing drake on Aikens Bay indicated that some drakes return to natal areas if unmated in the spring.
Numbers of Mallards seen in May and June aerial surveys of the marsh in 1973 increased 2.7 times over the previous three years’ average (Delta Waterfowl Research Station, unpub- lished data). This increase may have also been partially due to low water levels causing birds to be more visible than usual from the air. The extremely high density of Mallard pairs at Aikens Bay in 1973 was partly due to the homing of release hens since one-half of the females found there were marked. The unstocked Cooks Creek Meadow also contained a relatively high density of Mallard pairs. It is possible that higher than usual numbers of Mallards on wet areas of the marsh in 1973 masked the effects of the stocking effort. In contrast, the Diversion held comparatively few Mallards after two years of stocking. The number of pairs on the Diversion remained the same each year, and there was evidence that marked yearlings were homing to, but not remaining on, the site. Marked yearlings also were found along the lakeshore at Aikens Bay. It is likely that the study areas were filled to capacity with breeding pairs.
Reproductive behavior and success of first- time breeders differs from those of adults in many birds (Lack 1966). Bellrose et al. (1964) found that yearling Wood Ducks nested later than adults. Grice and Rogers (1965) showed that yearling Wood Ducks were less successful than adults in obtaining nesting sites when breeding populations were high. Heusmann (1975) indicated that limited nestings, smaller clutch size, and lower brood survival led to poorer annual production by yearling Wood Ducks. Gates (1962) found that adult Gadwall females established home ranges and began nesting earlier than yearlings in the spring. Stotts and Davis (1960) showed that adult Black Ducks
BAILEY: WILD MALLARD STOCKING 61
(Anas rubripes) were paired before yearlings and suggested that adults reach breeding “tempo” before hens nesting for the first time. Clutch size was also larger in adult Black Ducks. Mihelsons et al. (1970) found that yearling female Tufted Ducks started nesting later than the older birds and had comparatively poor success.
Yearling marked hens in this study arrived later on the release sites than most unmarked females, initiated nesting later, and were less successful than unmarked hens in producing broods. Lower productivity of released hens was apparently not caused by a lack of nesting cover, as found by Sellers (1973) because unmarked hens on the same areas were much more successful. Breeding by yearling hand-reared Mallards resembles a pattern observed in first- time breeders of other duck species, and lower productivity may be partly due to the fact that they are all breeding for the first time. The assumption that a considerable proportion of the unmarked Mallard population were adults was supported by the collecting of 15 hens.
Poor nesting success was also documented for a small sample of adult marked hens. Hence, the possible effects of hand-rearing on future breed- ing success remain unknown. It is important from a management standpoint to determine whether the differences observed between hand- reared and wild Mallards in this study are due to hand-rearing or age. The fact that no similar age- related breeding biology studies of wild Mal- lards are available to compare with these results points out an important research need. In view of the poor reproductive success of hand-reared - birds and the apparently high potential for natural immigration and production, Mallard stocking 1s of questionable value on the Delta Marsh.
Acknowledgments
I gratefully acknowledge the advice of J.R. Bider received during this study. Thanks are also due to B. D. J. Batt, P. Ward, and R. E. Jones for suggestions during the field study, and to them and A. J. Erskine, A. Dzubin, and R. D. Titman for review of the manuscript. The help of students and assistants at the Delta Waterfowl Research Station was appreciated. The com- ments and criticism of R.W. Stewart were invaluable throughout this study. R. McCulloch
62 THE CANADIAN FIELD-NATURALIST
assisted with the illustrations. Support of the Delta Waterfowl Research Station and Ducks Unlimited Foundation is acknowledged. I grate- fully acknowledge scholarships from the Na- tional Research Council of Canada and the Province of Québec.
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Doty, H. A. and A. D. Kruse. 1972. Techniques for esta- blishing local breeding populations of Wood Ducks. Journal of Wildlife Management 36: 428-435.
Dzubin, A. 1969. Assessing breeding populations of ducks by ground counts. /m Saskatoon wetland seminar. Canadian Wildlife Service Report Series 6. pp. 178-230.
Errington, P.L. and W.E. Albert, Jr. 1936. Banding studies of semi-domesticated Mallard ducks. Bird- Banding 7: 69-73.
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Foley, D. D., D. Benson, L. W. DeGraff, and E. R. Holm. 1961. Waterfowl stocking in New York. New York Fish and Game Journal 8: 37-48.
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Grice, D. and J. P. Rogers. 1965. The Wood Duck in Massachusetts. Massachusetts Division of Fish and Game, P-R Report Project W-19-R. 96 pp.
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Heusmann, H. W. 1975. Several aspects of the nesting biology of vearling Wood Ducks. Journal of Wildlife Management 39: 503-507.
Hochbaum, H. A. 1955. Travels and traditions of water- fowl. University of Minnesota Press, Minneapolis. 301 pp.
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Received 12 June 1975 Accepted 2 August 1978
Notes
Recent Collections of the Black Redhorse, Moxostoma duquesnei, from Ontario
EDWARD KotT,! ROBERT E. JENKINS,2 and GREGORY HUMPHREYS!
‘Department of Biology, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 2Department of Biology, Virginia Commonwealth University, Richmond, Virginia, USA 23284
Kott, Edward, Robert E. Jenkins, and Gregory Humphreys. 1979. Recent collections of the Black Redhorse, Moxostoma duquesnei from Ontario. Canadian Field-Naturalist 93(1): 63-66.
The Black Redhorse, Moxostoma duquesnei, a species considered endangered in Canada, was recently collected from two localities on the Nith River, a tributary of the Grand River, Ontario. It has not been collected in Canada since 1938. This species is often confused with M. erythrurum, the Golden Redhorse. A comparison between these species is included.
Key Words: Moxostoma duquesnei, redhorse suckers, Ontario, morphology, endangered species.
The Black Redhorse, Moxostoma duquesnei, 1s ROM9637 Ontario, Elgin County, Catfish Creek. 26 generally found in clear streams of moderate width March 1937. H. C. White. 1 adult. that are not subject to appreciable siltation. Because it © ROM10364 Ontario, Elgin County, Catfish Creek south is susceptible to siltation, it is becoming rare in many of Aylmer.