Quantifying the demographic and population impact of avian cholera on northern common eiders in the face of ancillary threats and changing environmental circumstances by Samuel A. Iverson M.Sc. A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology Carleton University Ottawa, Ontario © 2015, Samuel A. Iverson Abstract Emerging infectious diseases are on the rise globally; however, determining demographic impacts and the influence of disease on wildlife population dynamics remains a significant challenge. A poleward expansion of disease-causing pathogens has been predicted in association with globalization and climate change and historically unaffected Arctic wildlife may be particularly vulnerable to epidemic disease. My research examines the influence of newly emerged avian cholera outbreaks on northern common eiders (Somateria mollissima borealis) in the Canadian Arctic. Avian cholera is a highly virulent disease of birds caused by the bacterium Pasteurella multocida. I take advantage of a unique opportunity to investigate transmission dynamics and the impact of this disease on eider survival and reproductive rates in a marked population at Mitivik Island, Nunavut (64.030 N, 81.789 W). I also test hypotheses on ecological factors influencing spatial occurrence of the disease with data gathered from extensive site investigations, undertaken with the assistance of Inuit harvesters throughout the Hudson Strait region. To date, mass-mortality events have been confined to northern Québec (Nunavik) and Mitivik Island with annual mortality rates of up to 43% of the female nesting population at affected colonies. Consistent with expectations for a novel pathogen, case incidence increased in an exponential fashion during the initial wave of invasion (R0 = 2.5). Recurrent outbreaks were documented during eight consecutive breeding seasons at Mitivik Island and prolonged low-frequency transmission (Rt < 1) was evident at the epidemic tail—a hallmark of disease persistence facilitated by environmental transmission. Harvest mortality appears to be additive to disease mortality in this population, which is relevant because ii adjustment of hunting regulations is among the few logistically feasible interventions to conserve abundance. Demographic recovery has so far been constrained by a climate-mediated increase in the frequency of polar bear (Ursus maritimus) incursions onto eider breeding colonies and associated declines in nesting success. The causes and effects of emerging infectious diseases rarely operate in isolation from other ecological stressors and the types of information that I gathered informs scientific understanding of the interacting processes regulating population dynamics in the face of rapid anthropogenically-driven environmental change. iii Acknowledgements I am privileged to count myself among the small group of individuals fortunate enough to make a career in biology. I have never been as aware of this fact as during my time as PhD student at Carleton University. I would like to express my gratitude to Mark Forbes, who has been a tremendous mentor, advocate, and lightning quick advisor when lightning speed was required. I would also like to thank Grant Gilchrist for letting me into his Arctic playground and showing me the ropes. There were many ropes. The advice and criticism provided by my supervisory committee: Mark, Grant, Tom Sherratt, and Gabriel Blouin-Demers were invaluable and much appreciated. The logistics, permitting and stakeholder consultation required to implement an Arctic research project like mine requires the support of many people and I am particularly indebted to Amie Black, Mike Janssen, Christine McDonald, and Isabel Buttler in that regard. My field work was funded by the Nunavut Wildlife Trust, Nunavut General Monitoring Program, Nunavik Marine Region Wildlife Board, ArcticNet, and Canadian Wildlife Service. I was assisted in the field by members of the Cape Dorset, Iqaluit, Kimmirut, Kangiqsujuaq, Aupaluk, Kangirsuk and Ivujivik Hunters, Fishers and Trappers Associations. Field work was carried out and/or facilitated by Manon Simard and Sandy Suppa (Nunavik Research Centre), Gary Donaldson, Cédric Paitre and Jason Akearok (Canadian Wildlife Service), and Mark Travers, Amie Black, Jennifer Provencher, Jon Brown, Rian Dickson, Mike Janssen and Jeff Werner (Environment Canada, National Wildlife Research Centre). I benefitted tremendously from the long hours, commitment to detail, and bravery in the face of polar bears, infectious pathogens, and snow iv buntings (oh my) of the many biologists that have been stationed at Mitivik Island over the years. I expressly acknowledge the efforts of Grant Gilchrist in keeping the station afloat for all these years and for being the most generous collaborator I have ever run across. My academic support network at Carleton University, Environment Canada - National Wildlife Research Centre, and partner institutions was extensive. There are many people to thank and I apologize for any omissions. They include: Jennifer Provencher, Jane Harms, Catherine Soos, Guylaine Séguin, Paul Smith, Greg Mitchell, Tony Gaston, Sébastien Descamps, Mark Mallory, Ian Stirling, Manon Simard, Oliver Love, Joël Bêty, Stacey Robinson, and Julia Mlynarek. I would also like to than Peter Arcese and Kathy Martin for providing an academic home away from home at the University of British Columbia during the final stages of my write-up and to Dan Esler and John Takekawa for their perpetual mentorship. I was personally supported by scholarships from NSERC Canada through an Alexander Graham Bell Canadian Graduate Scholarship, the W. Garfield Weston Foundation, and the Kenneth M. Molson Foundation, as well as various and sundry grants provided to Dr Forbes and Dr Gilchrist. Finally, I wish to acknowledge the sacrifices that have been made by my family so that I could complete my dissertation. Thank you Risa, whom I love, and thank you Felix, who thought it normal to ask everyone in his day care class how their thesis was going. v Statement of Coauthorship This document follows an integrated thesis format and contains a General Introduction (Chapter 1), General Discussion (Chapter 6), and four data chapters configured as independent research articles (Chapters 2-5). One data chapter has already published (Chapter 4) and the necessary permissions have been obtained from the publisher for reproduction here. The remaining data chapters are currently under review or in preparation for scientific journal submission. I have received permission from each of my coauthors for the reproduction of our collaborative work in my thesis. My contributions to the research were as follows: (1) I proposed and developed the research questions outlined in the data chapters with input from my co-advisors Dr. M. R. Forbes (Carleton University) and Dr. H. G. Gilchrist (Environment Canada). (2) I was responsible for carrying out and/or supervising the field work described in the four data chapters. Specifically, I developed the field methodologies, hired and trained field assistants, and participated in the collection of the data. I was also granted access to a long-term dataset collected by biologists under the direction of Dr. H. G. Gilchrist (Mitivik Island) and Dr. A. J. Gaston (Cape Pembroke). (3) I was responsible for all of the data analysis and presentation of results for the data chapters. (4) I was responsible for all of the writing in this document, receiving helpful review comments on earlier drafts. vi Table of Contents Abstract........................................................................................................................................... ii Acknowledgements ....................................................................................................................... iv Statement of Coauthorship .......................................................................................................... vi Table of Contents ......................................................................................................................... vii List of Tables ................................................................................................................................ viii List of Figures ................................................................................................................................. ix Chapter 1: General Introduction .................................................................................................. 11 Chapter 2: Transmission dynamics and mortality patterns associated with an emerging infectious disease in an Arctic-nesting migratory bird ................................................................. 19 Chapter 3: Spatial distribution and ecological drivers of avian cholera emergence in the eastern Canadian Arctic ............................................................................................................................. 42 Chapter 4: Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic ............................................................................. 81 Chapter 5: Demographic impact and potential constraints population recovery following a highly virulent disease epidemic ................................................................................................. 107 Chapter