Why specialise? A comprehensive comparison of foraging behaviours of sea lion species

• Applicant: Jonas Schwarz, Ph.D.
• Subject Area: Sensory and Behavioural Biology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 525832609

The survival and reproductive success of predators is strongly dependent on their individual foraging strategies, which also play an important role in the coping ability of populations towards different environments. Sea lions, as apex predators, play a key role in the ecosystem. They have the potential to influence the structure of entire ecosystems through a variety of mechanisms and, as indicator species, help draw conclusions about the condition of the ecosystem. However, little research has been conducted on the development of sea lion foraging behaviour, which is essential for a deeper understanding of the consequences of a changing environment on sea lion populations. Therefore, the aim of this research project is to analyse the ecology of foraging behaviour of different sea lion species and colonies from diverse regions of the world, and to investigate the development and resulting consequences of different foraging strategies. The international cooperation between six sea lion research groups that I have established enables me to compare the diving behaviour of lactating females from different colonies of Galápagos, Californian, Australian, South American and New Zealand sea lions. The necessary dive data have already been collected in the past, but never directly put into relation to each other. Using a novel, comprehensive, and high-resolution analysis approach that I developed over the course of my PhD, I will analyse dive and location data from individuals of the North Pacific, Tropics, South Pacific and South Atlantic, Eastern Indian Ocean, and Southern Ocean. This allows me to describe foraging behaviour of sea lions from a wide variety of ecosystems in unprecedented detail, providing deep insights into the foraging ecology of these apex predators and highlighting behavioural differences among species, colonies, and individuals. Information on the geographic zone, stability of primary productivity, oceanic variability, bathymetric diversity, and inter- as well as intraspecific competition from the sea lion colonies provides the foundation to analyse the impact of a wide variety of factors on the development of foraging behaviour. This approach provides a clearer understanding of the roles that phylogeny, environmental factors, and ecological factors hold as drivers of foraging behaviour diversity, and offers deeper insights into the development of behavioural polymorphisms. Finally, I will examine the effects of foraging behaviour and its diversity, in relation to fishing intensity, on population trajectories. With this step, I will enable a better understanding of the multivariate causes that lead to variation in population dynamics of sea lion colonies.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professor Dr. Daniel Costa