EFFECTS OF AGE, GENDER, AND CONDITION ON THE REPRODUCTIVE EFFORT OF CASSIN'S AUKLETS (Ptychoramphus aleuticus) ON TRIANGLE ISLAND, BRITISH COLUMBIA. Hugh Arthur Knechtel B.Sc., Evergreen State College, 1993 THESIS SUBMllTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of BIOLOGICAL SCIENCES O Hugh Arthur Knechtel 1998 SIMON FRASER UNIVERSITY December 3 1998 All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author. National Libraty Bibliothèque nationale 1*1 ofCanada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. rue Wellington Ottawa ON KtAON4 Ottawa ON K1A ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence dowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/^ de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation, ABSTRACT The primacy goal of my research was to determine the effects of age, gender, and individual phenotypic quality (body reserves and immune function) on reproductive effort (egg size and laying date) in Cassin's Auklets (Ptychoramphus aleuticus) on Triangle Island, British Columbia. Breeding individuals were categorized as 'young' or 'oIdl based on iris colour. Two rneasures of condition were related to reproductive effort: body reserves (mass corrected for structural size) and immune function (heterophil :lymphocyte ratio or H:L ratio, an index of stress or infection). Although Cassin's Auklets exhibit a low degree of sexual dimorphism, I confirmed, using a molecular sexing technique, that bill depth is a reliable indicator of sex within breeding pairs. Using bill depth data from 115 pairs, 1 showed that 85% of randomly caught individuals could be accurately sexed. The ability to sex individuals is of value for determining gender in an ongoing mark-recapture study examining adult survival on Triangle Island. I further utilized the molecular sexing technique to show a male-biased offspring sex ratio close to fledging. Egg size variation was related to offspring 'quality': larger eggs produced hatchlings of greater mass and structural size. Although this effect did not persist beyond 5 days post- hatch, hatching from a large egg may lower starvation probability in years of poor food availability. 1 found significant age effects in some measures of female reproductive effort and condition, but not in others. Old females laid significantly earlier, but no age-related differences were found in egg size. By laÿing Iate, young fernales may have incurred greater fitness costs, since conditions are usually unfavourable for raising young later in the season. I found no age effect on female body reserves, however, the H:L ratios of young fernales were significantly higher, indicating greater stress or infection. Elevated H:L ratios in young females, but not in young males, may reflect the greater gametic effort of females (egg production). Variation in effort was related to condition in old breeders, but not in young breeders. Optirnization theory suggests that for individuals to maxirnize lifetime reproductive success, they should base reproductive effort on their condition, and maintain that level of condition throughout the breeding cycle. There was a positive correlation between laying date and H:L ratios in old males and fernales, but not in young breeders. This positive relationship in old males may mean that male 'quality' is important in determining laying date. Similarly, old fernales showed a positive correlation between body reserves and egg size, while young fernales did not. Since individual condition was measured late in incubation, the positive correlations between effort and condition in old, potentially more experienced individuals suggests that they are better at optirnizing current reproductive effort. Acknowledgments Many people contributed in various ways to rny research and the production of rny thesis. First and foremost, I thank rny supervisor, Fred Cooke, for this opportunity and for his support and patience throughout my journey. I am grateful to Tony Williams for introducing me to physiology, and for making valuable comments on the many drafts of this thesis. I thank Doug Bertram for his humour and advise since his arriva1 in the lab, and Ian Jones for passing on his bountiful knowledge of alcids and for his vision of a research station on Triangle Island. 1 will always be grateful for the enthusiasm shown to me by both Dov Lank and Evan Cooch; Dov in teaching me about behavioural ecology, and Evan in giving me statistical guidance. 1 also acknowledge the tireless work of Connie, Barb, and Joanne in keeping the lab on track and finely tuned. My research was funded by the CWS/NSERC Wildlife Ecology Research Chair and would not have been possible without the logistical support of the Canadian Coast Guard and West Coast Helicopters. 1 would like to thank the many people who have assisted me in the field. Foremost, 1 thank my volunteers, Uli Stiener and Edith Albertz, for their good humour and hard work grubbing burrows, measuring eggs, and bleeding birds through the hurricanes, storms, and cold of the early spring of '96. Thanks also to the colleagues who helped later that season: Alan Burger, Laura Cowen, Colleen Cassady St. Clair, Laura Jones, Suzzane Romaine, Mike WiIey, and Kerry Woo. Recognition is due to John Ryder and Kerry Woo for coliecting egg volume data for me the following year. Thanks also to Xia-Hua Xue and Brett Vanderkist for the many hours of lab work they put in to sex my birds. My time at Simon Fraser University was greatly enriched by the friendship and assistance of my lab mates and fellow grad students, for this 1 will always be grateful. My research benefited from discussions with Julian Christians, Chris Guglielmo, Brent Gurd, Anne Harfenist, Dave Moore, Patrick OIHara, Greg Robertson, Roxana Torres, and Brett Vanderkist. I also benefited from the many helpful comments on various drafts of this thesis provided by: Marion Blake, Ira Chaikin, Julian Christians, Chris Guglielmo, Brent Gurd, Cindy Hull, Lynn Lougheed, Dave Moore, Patrick O'Mara, Greg Robertson, Cyndi Smith, and Brett Vanderkist. Thanks to my family for the support they gave throughout my years at grad school. In particular, I thank my mother, Marion Blake, who showed me by example that anything is possible if you put your mind to it. Table of Contents APPROVAL ............................................................................................................................ ii ABSTRACT ............,,,............................................................................................................iii ACKNOWLEDG EMENTS....................................................................................................... v TABLE OF CONTENTS........................................................................................................... vi LIST OF TABLES..................... .. ....................................................................................... viii LIST OF FIGURES ................................................................................................................. ix CHAPTER 1. GENERAL INTRODUCTION........................................................................... 1 Study Species ..................................................................................................................... 6 Study Site........................................................................................................................... 9 Objectives...........,.......................................................................................................... 1 1 CHAPTER 2. SEXING CASSIN'S AUKLETS: METHODS AND PRELlMlNARY SU(-RATIO DATA ...................................... ,,. ....................................................................................... 1 3 Abstract ............................................................................................................................ 1 3 Introduction.................................................................................................................... 1 3 Methods............................. ... ............................................................................................ 1 4 Results............................................................................................................................. 1 6 Discussion........................................................................................................................ 1 6 CHAPTER 3. AGE-RELATED DIFFERENCES IN THE RELATIONSHIP BETWEEN REPRODUCTIVE EFFORT AND MATERNAL BODY RESERVES, AND THE INFLUENCE OF EGG SlZE ON HATCHLING SlZE AND MASS IN CASSIN'S AUKLETS ..........................................................................