Individual Specialisations in the Foraging Ecology of Seabirds
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Individual specialisations in the foraging ecology of seabirds by Elodie Claire Marie Camprasse B.Sc. (Biology of Organisms and Populations) M.Sc. (Marine Environment and Resources) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Deakin University, April, 2017 DEAKIN UNIVERSITY ACCESS TO THESIS - A I am the author of the thesis entitled Individual specialisations in the foraging ecology of seabirds submitted for the degree of Doctor of Philosophy This thesis may be made available for consultation, loan and limited copying in accordance with the Copyright Act 1968. 'I certify that I am the student named below and that the information provided in the form is correct' Full Name: Elodie Claire Marie Camprasse Signed: Date: 20th April 2017 i DEAKIN UNIVERSITY CANDIDATE DECLARATION I certify the following about the thesis entitled Individual specialisations in the foraging ecology of seabirds submitted for the degree of Doctor of Philosophy a. I am the creator of all or part of the whole work(s) (including content and layout) and that where reference is made to the work of others, due acknowledgment is given. b. The work(s) are not in any way a violation or infringement of any copyright, trademark, patent, or other rights whatsoever of any person. c. That if the work(s) have been commissioned, sponsored or supported by any organisation, I have fulfilled all of the obligations required by such contract or agreement. d. That any material in the thesis which has been accepted for a degree or diploma by any university or institution is identified in the text. e. All research integrity requirements have been complied with. 'I certify that I am the student named below and that the information provided in the form is correct' Full Name: Elodie Claire Marie Camprasse Signed: Date: 20th April 2017 Deakin University CRICOS Provider Code 00113B ii ABSTRACT Individual specialisations in foraging involve the repetition of specific behaviours or dietary choices over time; they are thought to help individuals mitigate competition and increase foraging efficiency. Even though individual specialisations are now known to be commonly exhibited in natural populations and have the potential to influence ecological processes and foraging dynamics, their drivers and the timescales over which they are maintained are not well understood. Furthermore, quantifying the degree of specialisation is important as even populations considered to be generalists can be made of individual specialists. Lastly, a balance between individual specialisations and behavioural flexibility over different timescales might be necessary for populations to effectively cope with changes in prey availability. Seabirds are central-place foragers during the breeding season, as they generally nest in colonies, to which they return and in which individuals compete for and have access to the same resources. Three seabird species with different foraging habits were selected and a combination of bio-logging and stable isotope analysis was used to: (i) quantify the degree of individual specialisation in foraging behaviour; (ii) investigate the influence of intrinsic and extrinsic factors on individual specialisations; (iii) determine timescales over which such specialisations are maintained; and (iv) examine whether individual specialisations could be related to mate choice. Kerguelen shags Phalacrocorax verrucosus exhibited short- and medium-term consistency in foraging behaviour and strong long-term dietary specialisations that were not related to morphology or sex but rather seem to match different prey preferences. In this species, mates were more similar in behaviour and diet than expected by chance. Gentoo iii penguins Pygoscelis papua exhibited low to moderate short-term consistency in foraging metrics at the population level, independently of sex or morphology, and dietary specialisations maintained outside of a single breeding season. In Little penguins Eudyptula minor, low to moderate consistency was exhibited in some aspects of their foraging behaviour on a day-to-day basis but was not evident over longer timescales, highlighting the species’ behavioural plasticity. The findings of the present study, in conjunction with the ones of previous studies, highlight the importance of extrinsic drivers such as ecological opportunity, foraging modes (e.g. benthic vs pelagic) and sites (e.g. polar vs tropical) in determining the degree of individual specialisation. Such drivers are likely to be reinforced by intrinsic factors (e.g. physiological capacity, experience, cognitive and learning capacities). Memory-based foraging, for example, might be used depending on prey availability and diversity, resulting in site fidelity and stereotyped behaviours. In the present work, I highlighted the importance of taking timescales into account when determining the degree of individual specialisations in seabird populations as results on short timescales might not be consistent with those over longer timescales. Furthermore, it seems crucial to develop standardised metrics and analytical methods to use in order to be able to make meaningful comparisons between the degrees of individual specialisation exhibited by different species and between populations of the same species. Lastly, extending the number of species studied to cover a wider range of individual morphological and physiological variations, foraging modes and locations will help ecologists gain a deeper understanding of the drivers of individual specialisations. iv Preface Field work for the present study was done in accordance with the ethical guidelines of the Deakin University Animal Ethics Committee and Animal Welfare Committee (Permit No. B21-2013), as well as of the French Polar Institute Paul-Emile Victor’s Ethics Committee (Program 394). The project was conducted in accordance with the regulations of Parks Victoria and of the Department of Environment, Land, Water and Planning (Wildlife Research Permit No. 10006877). The core data chapters of this thesis (Chapters 2 to 5) have been published in peer- reviewed journals. Chapter 1 stands as an introduction to the main body of work while Chapter 6 places the main findings of the study in a more general context. I am the primary contributor to all aspects of the work presented in this thesis, with the exception of diet determination for Chapter 2 and the data collection for Chapter 5. John P.Y. Arnould, Yves Cherel, Charles-André Bost are co-authors on all publications for providing financial and logistical support, contributing to the study designs, and providing equipment, guidance, and editorial advice. Andrew Hoskins provided invaluable insight about statistical analysis for Chapters 2 and 3. Yves Cherel identified prey items in the regurgitates collected on Kerguelen shags. Paco Bustamante, Maud Brault- Favrou and Gaël Guillou contributed to sample preparation and isotopic analysis for Chapters 2, 3 and 4. Selina Kent, Maud Berlincourt, Melanie Wells and Grace Sutton all participated in the collection of the data on Little penguins used in Chapter 5. v Publications arising from this thesis Chapter 2 Camprasse E.C.M., Cherel Y., Arnould J.P.Y., Hoskins A.J., Bost C.A. (2017) Combined bio-logging and stable isotopes reveal individual specialisations in a benthic coastal seabird, the Kerguelen shag. PLoS ONE 12(3): e0172278. https://doi.org/10.1371/journal.pone. 0172278 Chapter 3 Camprasse E.C.M., Cherel Y., Arnould J.P.Y, Hoskins A.J., Bustamante P., Bost C.A. (2017) Mate similarity in foraging Kerguelen shags: a combined bio-logging and stable isotope investigation. Marine Ecology Progress Series. https://doi.org/10.3354/meps12259 Chapter 4 Camprasse E.C.M., Cherel Y., Bustamante P., Arnould J.P.Y., Bost C.A. (2017). Intra- and inter-individual variation in the foraging ecology of a generalist subantarctic seabird, the Gentoo penguin. Marine Ecology Progress Series. https://doi.org/10.3354/meps12151 Chapter 5 Camprasse E.C.M., Sutton G.J., Berlincourt M., Arnould J.P.Y. (2017). Changing with the times: Little penguins exhibit flexibility in foraging behaviour and low behavioural consistency. Marine biology 164: 169. https://doi.org/10.1007/s00227-017-3193-y. vi Acknowledgements “And she's going on a journey Always walking down the road And the water is always calling "My little child, please come home." That's when she went away Away from the light of day Standing by the riverside Patiently waiting for the tide To come along, to come along The waters going to her feet And on her body wind so cold and sweet, so cold and sweet” Awakening – Aurora I owe my passion for the ocean to my father, Rémi. Ever since I started scuba diving thanks to him, I had sworn to myself I was going to become a marine biologist. I owe my passion for travelling to both my mother, Carole, and my father; they have taken me around the world, helped me experience and respect different cultures and I certainly would not be where I am today if it was not for them. I am proud to have such wonderful and supportive parents and I am grateful for the education I received from them and the rest of my lovely family; they have taught me how to be adventurous and independent, even though they would vii want to see me more often! I know being away for that long has been hard on you and I hope seeing my achievements has been reward enough. Maman, Papa, merci! Je vous aime et vous m’avez manqué souvent. I am also very lucky to have wonderful, dynamic and successful cousins to inspire me, a brother who has fought worse battles than I have, and loving and caring step-mother, grand-mother, aunts and uncles. We did not communicate much during these busy past few years but it was always a pleasure when we did; you are always in my heart and I am looking forward to catching up with you soon hopefully. To the three grandparents I lost just before or during my PhD, I am sorry I have not gotten to say goodbye.