6 Raptor Research Foundation, Inc. and Macdonald Raptor Research Centre of McGill University ISBN: 0-935868-34-8 Proceedings of a. Symposium on Kestrel Species St. Louis, Missouri, December 1st, 1983 The Ancestral Kestrel Edited by DAVID M. BIRD and REED BOWMAN RAPTOR RESEARCH REPORTS NO.6 RAPTOR RESEARCH FOUNDATION, INC. MACDONALD RAPTOR RESEARCH CENTRE OF MCGILL UNIVERSITY 1987 First published 1987 by Raptor Research Foundation, Inc. and Macdonald Raptor Research Centre of McGill University. © 1987 Raptor Research Foundation, Inc. and Macdonald Raptor Research Centre of McGill University. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owner. Printed and bound in the U.S. by Allen Press, Inc., Lawrence, Kansas. This publication was produced using lDTE)X, a document preparation macro package based on the 'J.EX typesetting system. Suggested quoting title: BIRD, DAVID M. and REED BoWMAN(eds.). 1987. The Ancestral Kestrel. Raptor Res. Found., Inc. and Macdonald Raptor Res. Centre of McGill Univ., Ste. Anne de Bellevue, Quebec. Preface My feelings about kestrels are probably best summed up by the fact that I have bred in captivity over 1,500 of them, yet I still get that special thrill from watching a. single wild bird hovering intently over a. roadside ditch. It is that same feeling which brought together about one hundred people to hear about "The Ancestral Kestrel" at a. symposium on kestrel species on December 1, 1983 1n St. Louis, Missouri. Twenty papers were presented in all, originating from kestrel sxperts from five countries. Naturally, the U.S. and Canada. were the most heavily represented and hence, the symposium focused mainly on the American Kestrel (Falco sparuerius). Since 1844, more than 450 articles have been published on the American Kestrel alone, 90 of which featured the species as an experimental animal. Although used somewhat less as a. laboratory animal, similar statistics could likely be generated for the Eurasian Kestrel (F. tinnunculus). According to Douglas Boyce and Clayton White in their lead paper on kestrel evolution and systematics, there are 15 species of kestrel world-wide, if one includes the Red-footed Falcons (F. uespertinus and F. amurensis). Moreover, the American Kestrel is perhaps the most recently evolved kestrel and is, in fact, the only New World representative of the kestrel's subgenus tinnunculus. Formerly known as the Sparrow Hawk, the American Kestrel is closely related to its old world cousin, the Eurasian Kestrel. Mark Fuller, Danny Bystrak, Chandler Robbins and Robert Patterson examined trends in counts from the North American Breeding Bird Survey to conclude that the American Kestrel is the most common diurnal ra.ptor throughout its range in North America.. Andrew Village of the U.K. reviewed published information on population regu­ lation in kestrels to find considerable variation in dispersion patterns both within and between species. Possible mechanisms for population regulation within and outside the breeding season are suggested, along with experiments which might test their validity during the breeding season. Paper themes then become more localized as Carlos Wotzkow Alvarez and Jorge de la Cruz Lorenzo of Cuba. discuss their findings on the nesting success of the American Kestrel (F. s. sparuerioides), a. little studied race to date. Another subspecies of American Kestrel, F. s. paulus, is featured in an article by Mark Hoffman and Michael Collopy who examined its distribution and nesting ecol­ ogy near Archer, Florida.. Petra Bohall-Wood also teams up with Michael Collopy to determine the foraging behavior of these same kestrels in relation to their habitat use. As a. more general follow-up to the latter paper, Keith Bildstein and Michael Collopy offer an excellent review of the literature on both American and Eurasian Kestrels to discuss their hunting behavior and success in light of current ecological thought. Stimulating suggestions for further research are also given. Even more controversial is prey selection by kestrels. To this end, Helmut Mueller provides a rather lengthy, but thought-provoking critique of published results of both laboratory and field experimentation on prey selection, including his own extensive stud­ ies. III Two other current thorny issues are habitat separation by sex in wintering American Kestrels and reversed size dimorphism in birds of prey. Ruthe Lash Meyer and Tom Balgooyen tackle both these topics in their•study of wintering American Kestrels in central California.. What all of the above really comes down to in the final analysis is the balance of energy gained and lost. Dirkjan Masman and Serge Daan of The Netherlands provide an excellent summary of their 700 days of continuous observation on Eurasian Kestrels throughout their annual cycle to determine allocation of energy. The annual changes in the daily use of energy were constructed for both sexes in terms of repro­ duction, moult and thermoregulation. They also discuss the energetic consequences of alternative behavioral patterns. Their study is neatly followed by one on the energetics of the American Kestrel in northern Utah by James Gessaman and Lucinda Haggas. They computed daily energy expenditures for three different periods of the year: non-breeding, breeding, and post-breeding. Next, Reed Bowman, Jim Duncan and David Bird delve into the behavioral ecology of the American Kestrel by examining data from four long-term banding projects across North America to estimate rates of natal philopatry and adult site tenacity. Alan Kemp momentarily diverts our attention from the more common, well-known kestrels by presenting data on linear and weight measurements of mated pairs of Greater Kestrels (F. rupicoloides). He nicely ties the information together into discussions of reversed size dimorphism and biological fitness of individuals. Despite the overwhelming success of nest box programs for kestrels around the world, there is always room for improvements. Tom Wilmers perused the literature to con­ clude that Starlings (Sturnus vulgaris), perhaps the kestrel's main competitor for nest sites, shun nest boxes with large entrances and high interior light levels. Elizabeth Curley, Reed Bowman and David Bird took Wilmer's ideas one step further by field-testing them. Indeed, Starling occupation can be reduced by decreasing the amount of cover above the boxes and by orienting the opening of the boxes such as to maximize light intensity in them. Lastly, both American and Eurasian Kestrels breed readily in confinement, the for­ mer first bred in 1921 and the latter as early as 1850. Moreover, the American Kestrel was particularly valuable in helping to indict DDT as a significant cause of reproduc­ tive failure in wild birds. Both species of kestrel have actually contributed far more to the field of toxicology, as Stanley Wiemeyer and Jeffrey Lincer point out in their comprehensive review of the subject. Beyond any doubt, both kestrel species will continue to make contributions toward the management and conservation of birds of prey, as well as toward avian biology in general. Books on both species are already in the works by Andrew Village and myself. Each of the sixteen papers included in these proceedings was subjected to rigorous reviews by two referees and in some cases, an in-house review as well. Disagreements were resolved by a third referee. Additionally, each paper was scrutinized by two finicky editors, Reed Bowman and myself. If I had one misgiving about these proceedings, it would be the considerably long delay between the actual symposium and their publica­ tion. The reasons for this are not worth discussing here. In spite of the delay though, I am very confident that each paper has been adequately updated to provide fresh, original thinking on the subject. The editors gratefully acknowledge the kind assistance of the following referees: Tom Balgooyen, Keith Bildstein, Peter Bloom, Sandy Boyce, Michael Collopy, Serge Daan, Jim Enderson, Jim Gessaman, Charles Renny, Alan Jenkins, Roger Jones, Alan IV Kemp, James Koplin, James Layne, Harry Lumsden, Carl Marti, Dirkjan Masman, David Peakall, Seri Rudolph, Fred Sheldon, Steve Sherrod, John Smallwood, Dwight Smith, Karen Steenhof, Christopher Stinson, Andrew Village, and Tom Wilmers. Marie Kubecki is thanked for her assistance with word processing. I also extend my gratitude to the Department of Renewable Resources of McGill University for use of their facilities, to the Raptor Research Foundation, Inc. for allowing me to piggyback the symposium on their annual conference, and to Walter Crawford for being such a helpful .host. Lastly, I offer special thanks to Shawn Farrell, Word Processing Consultant at McGill's Computing Centre, for introducing me to the world of PC 'lEX, which added considerable polish to these proceedings. DAVID M. BIRD v Table of Contents Preface . III Evolutionary Aspects of Kestrel Systematics: A Scenario Douglas A. Boyce Jr. and Clayton W. White ..... 1 Trends in American Kestrel Counts from the North American Breeding Bird Survey Mark R. Fuller, Danny Bystrak, Chandler S. Robbins, and Robert M. Paterson . 22 Population Regulation in Kestrels Andrew Village . 28 Nesting Success of the American Kestrel (Falco sparverius sparverioides Vig­ ors) in the Boca de la Jaula, Tapaste, Havana Province Carlos Wotzkow Alvarez and Jorge de la Cruz Lorenzo . 43 Distribution and Nesting Ecology of the American Kestrel (Falco sparverius paulus) near Archer, Florida Mark L. Hoffman and Michael W. Collopy. 47 Foraging Behavior of Southeastern American Kestrels in Relation to Habitat Use Petra G. Bohall- Wood and Michael W. Collopy . 58 Hunting Behavior of Eurasian (Falco tinnunculus) and American Kestrels (F. sparverius): A Review Keith L. Bildstein and Michael W. Collopy . 66 Prey Selection by Kestrels: A Review Helmut C. Mueller ........ 83 A Study and Implications of Habitat Separation by Sex of Wintering American Kestrels (Falco sparverius L.) Ruthe Lash Meyer and Thomas G.