Behavioural consistency and foraging specialisations in the Australasian gannet (Morus serrator) By Marlenne Adriana Rodríguez Malagón B.Sc. Biology, M.Sc. Ecology Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy (Life & Env) Deakin University October 2018 i To MM and JMB, for your unconditional love and your faith in me, thanks to you I fulfilled this dream. I love you ii ABSTRACT For decades conspecifics were considered as equivalent in ecological studies, but recent science now recognises the presence and importance of inter-individual differences. These differences can be driven by intrinsic factors such as sex, phenotype, and/or personality, and are known to influence individual foraging decisions. The concept of ‘individual foraging specialist’ refers to the use of a specific proportion of the full range of available resources (or foraging strategies) used by a subset of a population and involves the repetition of specific behaviours over time. Furthermore, behavioural consistency and/or individual specialisation can arise within different aspects of a species’ ecological niche. The presence of both phenomena may vary over spatial and temporal scales due to environmental stochasticity, but because these phenomena can have major implications for the ecology of individuals, it is important to identify and quantify the presence individual foraging specialisation and behavioural consistency in animal populations. Seabirds are major marine predators and traits such as colonial breeding, central-place foraging during the breeding season, and high levels of nest-site fidelity make them good models to investigate behavioural consistency. The Australasian gannet (Morus serrator) is a large pelagic seabird endemic to Australia and New Zealand. It is considered a generalist predator with high levels of foraging plasticity. However, little is known about the factors influencing behavioural consistency in this species. Thus, the objectives of this research project were to determine: 1) the level of inter- and intra-individual variation within foraging behaviour, diet and winter dispersal patterns in Australasian gannets, 2) how these attributes vary over different timescales and habitats, and 3) the factors influencing these same attributes. Data were collected at two breeding colonies in southeastern Australia, Point Danger and Pope’s Eye, which are subject to contrasting oceanographic conditions and foraging habitats. A combination of bio-logging, stable isotope analysis, and diet analysis was used to v investigate behavioural consistency. Breeding individuals and in most cases, their nest partners, were sampled over two breeding seasons. The present study found that colony, breeding stage, year, and sex were factors influencing the foraging behaviour of Australasian gannets and the isotopic values (δ13C and δ15N) measured in blood plasma of individual adults. Behavioural consistency, measured as the contribution of the individual to the observed variance based on all study birds, was low to moderate for the five foraging metrics tested (maximum distance from the colony, bearing from the colony to the most distal point, tortuosity index, total number of dives, and mean Vectorial Dynamic Body Acceleration [VeDBA]), with greater consistency values occurring over shorter timescales. Similarly, intra-individual diet variation was lower over medium timescales (breeding stage-to-breeding stage), compared to long timescales (year- to-year). In addition, behavioural consistency in foraging activity and the average degree of individual diet specialisation were both higher in individuals foraging in inshore, shallow water habitats compared to those foraging in pelagic habitats, supporting the notion that consistency is favoured in more stable environments. Finally, similarity between nest partners in trophic levels (δ15N values) was found, although no reproductive advantage was observed in relation to the degree of similarity. Regarding winter dispersion behaviour, Australasian gannets exhibited differences between the two sampled colonies and between years, as well as between sexes. Study individuals could be separated into three distinctive winter dispersal strategies based mainly on location, distance from colony, and duration. Intra-individual similarity in winter dispersal behaviour between two years was found in bearing from the colony to the most distal point and in return dates to the colony. In addition, nest partners showed similar values in departure dates, bearing, and return dates, suggesting coordinated behaviour between members of a mated pair. The findings of the present study highlight the presence of behavioural consistency in Australian gannets, and give insights about its potential drivers. More importantly, this study vi reveals ecological opportunity as a major component for the development of foraging consistency and foraging specialisation in wildlife populations. Additionally, this research contribute with the understanding of the level of resource partitioning among the individuals of the two study populations, which is crucial information for their conservation and management. vii PREFACE The animal handling procedures conducted for the present study complied with the ethical guidelines of Deakin University Animal Ethics Committee under Approval B20-2013. The fieldwork was conducted in accordance with the regulations of Parks Victoria and Department of Environment, Land, Water and Planning (Wildlife Research Permit No. 10006878, File No. FF383295), issued to Professor John Arnould. The student conducted all leg banding of birds under an Australian Bird and Bat Banding Scheme R Class Banding Licence (No. 3168). Two chapters of this thesis (Chapters 2 & 3) have been submitted for publication in peer- reviewed journals. Chapter 1 serves as an introduction to the main body of work while Chapter 6 discusses the main findings of the study within the context of the larger field of study. I am the primary contributor to all aspects of the work presented in this thesis, with the exception of the minor additional data collection for Chapters 3, 4, and 5 and the data analysis of Chapters 2 and 5. John P.Y. Arnould is a co-author on all submitted publications for providing logistic and financial support, contributing to the study designs and required permits, providing equipment, editorial advice, guidance, and general support in all aspects of my PhD. Chapter 2 - Elodie C.M. Camprasse and Lauren P. Angel contributed substantially to the data analysis about linear mixed effect models and accelerometry data, respectively. Chapter 3 - Lauren P. Angel contributed to fieldwork and collection of marine prey samples. viii Chapter 4 - Lauren P. Angel contributed to fieldwork and collection of bird blood samples. Chapter 5 – Mark A. Hindell and Melanie R. Wells contributed substantially to the analysis of the geolocation data, and with fieldwork activities for the recovery of the geolocators loggers from the birds, respectively. ix Publications arising from this thesis Chapter 2 Marlenne A. Rodríguez-Malagón, Elodie C.M. Camprasse, Lauren P. Angel and John P.Y. Arnould (in review). Influences on foraging behaviour and consistency in a marine aerial predator. Royal Society of Open Science. Chapter 3 Marlenne A. Rodríguez-Malagón, Lauren P. Angel and John P.Y. Arnould (in review). Temporal and spatial variability in isotopic niche of marine prey species in south-eastern Australia: potential implications for predator diet studies. Marine Biology. x ACKNOWLEDGEMENTS Empezaré por agradecerle a mi familia, la cual fue, ha sido y seguirá siendo siempre mi mayor soporte de vida. A mi madre hermosa que siempre ha creído y disfrutado de mis sueños tanto como yo, a mis queridas hermanas Martha y Queta, a mis sobrinas Renné y Luna a quienes extraño todos los días y por la cuales lamento no estar cerca para disfrutarlas y verlas crecer. Ustedes saben que las amo. Al resto de mi familia, tíos, tías, primos y sobrinos, de los que siempre he recibido apoyo y cariño y quienes me recuerdan todo el tiempo que la familia es el tesoro más grande que la vida te puede brindar. Gracias a todos ustedes por estar siempre a mi lado. A mi querida familia australiana: Edgar, Laura, Jorge, Mayte, Mayela, Paco, Karina, Tere, Pablo, Débora, Pablo Juliano, Lisa, Leo, Sue, Michael, Fernanda, Sergio, Luis, Nora y Fernanda V., quienes me adoptaron desde mi llegada y me han hecho sentir querida y apoyada en estas tierras lejanas. Les agradezco mucho esa hermandad y todos los buenos momentos. A mis queridas amigas y hermanas de vida Darlene Guerra y Alejandra Portillo, quienes en los últimos meses de este viaje me ayudaron a seguir de pie, me enseñaron a conocerme a mí misma y a ser una mejor persona. Por esto, les estaré a ambas eternamente agradecida. Finalmente, a ‘mi héroe’, ese ser de noble corazón que me ha acompañado en muchos buenos y malos momentos, que me ama, me cuida y me cocina, y que siempre encuentra la manera de sacarme una sonrisa. A ti, todo mi ser y todo mi amor! Gracias por esta hermosa y divertida aventura que es vivir! I will start by thanking my family which was, has been and always will be my greatest support in life. To my beautiful mother who has always believed in me and has enjoyed my dreams as much as I do; to my beloved sisters Martha and Queta; to my nieces Renné and Luna, whom I miss every day and regret not being close to cherish and see them grow, you xi know I love you. To the rest of my family, my uncles, aunts, cousins and nephews, who have always loved and supported me, and constantly remind me that family is the greatest treasure in life. Thank you for always being by my side. To my dear Australian family: Edgar, Laura, Jorge, Mayte, Mayela, Pablo Juliano, Paco, Karina, Tere, Pablo, Débora, Lisa, Leo, Sue, Michael, Fernanda, Sergio, Luis, Nora and Fernanda V., who adopted me since my arrival to the country and have made me feel loved and supported in these distant lands. Thank you very much for your brotherhood and all the good times. I also want to give special thanks to Jenny, Molly and Max Cummings, who were at first my landlords and soon after became my friends and family.