PAR FORMATION, MATING SYSTEM, AND WINTER PKILOPATRY IN HARLEQUTN DUCKS. Gregory James Robertson B.Sc.H., Queen's University, 1992 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE. REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the-Department Biological Sciences 0 Gregory James Robertson 1997 SIMON FRASER UNIVERSITY October 1997 t All rights reserved. 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Neither the droit d7auteurqui protege cette these. thesis nor substantial extracts from it Ni la these ni des extraits substantiels may be printed or otherwise * de celle-ci ne doivent Ctre irnprirnes reproduced without the &@or's ou autrement reproduits sans son permission. >, ; autorisation. APPROVAL Name: Gregory James Robertson 'tn ' 4. ~e~ree:' t Doctor of Philosophy Title of Thesis: '% '% pa& formation, mating system, and winter philopatry in Harlequin Ducks. Examinkg Committee: P Chair: Dr. Tony Williams, Associate Professor ~rT&edCooke, Professor, Senior Supervisor Department of ~ylo~icalSciences, SFU -- Vgfieek', Professor artment of Biological Sciences, SFU Dr. Ronalil4khMrg, Professor Department of Biological Sciences, SFU ~r.qi~'e:oudie:Research Scientist Canadian Wildlife Services - Dr. Bernard Roitberg, Professor Department of Biglo-, SFU Public Examinep/- University of California, Davis Egternal Examiner P Date Approved: 2 Z- C? c-4 ' 7 7 Y Abstratt Current theory suggests that msing systems influence the direction of a sex-bias in philopatry. Most bird species form pair bonds on the breeding grounds and exhibit a ? resource based mating system, leading to the evolution of male-biased breeding philopatry Males returning to familiar territories are expected to have a competitive advantage. In contrast, many waterfowl species form pair bonds during the nori-breeding season and their mating system at the time of pair bond formation is not known. In this thesis, I 1 studied the Harlequin Duck Histrioniczi.s histrioniczrs, to determine: which factors (such as f feather moult) influencewhen pair- bonds form, the mating system and jo test whether this 0 species follows the predicted sex-bias in philopatry given the observed mating system 4 A moulting and wintering population of about 100 Harlequin Ducks was studied from jl' 1994 to 1997 in coastal southwestern British Columbia. Harlequin Ducks formed pair e ~ bonds in October and November and pairs reunited. Males immediately began their feather moult after they returned from the breeding grounds. Males tended to clump into groups while they were moulting and grew in a set of bright white tertial feathers while they were in their basic plumage. Males may use these feathers as a badge to assess the timing and speed of moult of others. Males that moulted slowly were shown to be at a disadvantage when'attempting to attract a mate and were likely to be low quality individuals. Harlequin 1 Ducks form pair bonds as soon as possible, after the annual body moult is complete. Males did not isolate themselves from other males and did not exhibit conspecific rA. -iJ aggression along spatid boundaries, suggesting that Harlequin Ducks are not territorial during the winter. They did behave aggressively towards males that approached their i mate. These observaions suggest that Harlequin Ducks have a mate-defense mating system, and should exhibit a female-biased philgpatry. However, both sexes show equally high levels of winter return rates (females: 62%, males: 77%). The mating system was not successfid in predicting a sex-bias in winter philopatry, probably because the benefits of . * returning to fhiliar habit& are hgh for both sexes. , Acknowledgments This journey began in the summer of 1990. Although the work I did at La PCrouse Bay Z has absolutely nothing to do with ths thesis, it isathe place where I became a field biologist. Matt, James, Rocky and all the other bozos I worked with up there played a role in teaching me this business, thanks guys. Fred has fieely given me his very precious time for endless discussions about Harlequin Duck biology and waterfowl ecology. HISinput and ideas are present throughout ths - thesis. Thank you Fred, for malung it all possible. Tony was the first person to teach me how to write science, among many, many other thngs. More importantly he has always been a close fhend Tony, en and Natasha, I wish you all the best in the fbture. Besides the obvious statistical guidance I have received from Evan, he also taught me how to teach > it to others. 1 shall remember our discussions about all sorts of issues, the politically correct ones and the others.", Dov taught me how to think critically and th$jntimidating -- T, -z P equations and graphs can be understood. He also gave me the opportunity to play trucker for a week with all of his worldly possessions. Brett introduced me to the wilds of Btitish Columbia, spoiling me forever. Eric and I \. learned how to bag ducks together. Standing in the middle of ~oundar~Bay at 0530h, in the pouring rain, are some of my best memories in the last 5 years. Pat let me take his bike and boat apart, leaps of faith that I appreciate. Bill just tried to lull me, but we had a gdat time. Sean, Howie, Dave, Yo, Andrew, Tom, Brent, Chns, Don, Steph, Irene and all the others, thank for your fnendship. I would like to thank the dozens of people who have assisted us in collecting Harlequin Duck data. Carl, Jamie, Ned, Ken, Billie, Shawn, Roxana and Joanne deserve special , mention. lan Goudie is responsible for initiating the Harlequin Duck research effort in British Columbia, a huge, and by all accounts, successfid undertalung. Sean Boyd, has spent many hours observirg Harlequin Ducks and made the initiative to use radio telemetry with this species. Ian and Sean's contribution to ths thesis is invaluable, more importantly, they are extremely easy and enjoyable people to work with. It. has been a ' pleasure. Billie Gowan's work, although, not directly of this thesis is a key component of our current understanding of Harlequin Ducks. Discussions with Roxana Torres, 9 Malcolm Coupe, Billie Gowans, Ken Wright, Cyndi Smith, Bill Hunt, and Shawn Ternan about sea ducks and Harlequin Ducks helped to expand and clarifi my ideas. Connie, Joande and Barb, from someone who has dabbled in logistics and accounting, your efforts to keep the ship afloat do not go unnoticed. My comfutee members, Ron and Nico, . provided me with lots of good advice and suggestions. Jill, thank you for being thqe. To my parents and brother, although you have only a vague of idea of what I do for a living, you never once questioned the decision and gave . - me '1 00% support. Thanks. Various parts of the research presented in this thesis were generously hnded by: the \ Natural Sciences and Engineering Research Couscil of Canada (NSERC), the British Columbia Waterfowl Society, the Institute for Wetland and Waterfowl Research, the Canadian Wildlife Service, the CWS/NSERC Wildlife Ecology Research Chair and Simon Fraser University. Z able of Contents .. Approval ...............................................................................................:....................... 11... Abstract ......................................................................................................................111 Acknowledgments .......................................................................................................v Table of Contents .........................................................................................................vii List of Tables ..............................................................................................................ix List of Figures ..............................................................................................................x Preface ......................................................................................................................... xi Chapter 1 - General introduction ..................................................................................1 7 1 . 1. Introduction to the thesis ........................: ................................................ : 1 1.1.1. The research question ..... r: .......................................................... 1 1.1.2.The studyqecies..................................................................... 3 1.1.3.Outline of the thesis .................................................................... 6 1 2 Winter philopatry in migrate r). waterfowi ................................................... 8 12.1 Abstract .................................................................. .............. 8 1.2.2Introduction ...........