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Abstract

Seabirds are the most threatened of all birds, with half of all populations being on decline due to anthropogenically driven changes to their environment. Many of the issues affecting seabirds are directly or indirectly tied to their foraging, but tracking seabirds’ food resources has been challenging due to their extensive ranges. With novel technologies, fine-scale information on prey distributions is increasingly accessible, enabling new insights into predator-prey interactions. In this thesis, I contribute with knowledge on how diving seabirds utilize and respond to dynamic prey landscapes, with a particular focus on niche divergence among closely related predators. I explored the ecological consequences of predator adaptations in relation to foraging behaviour, environmental variability, and the consequences of adaptations to seabirds’ conservation on a global scale. I first investigated the utility of hydroacoustic prey data monitored using an unmanned surface vehicle from April-July in 2019-2023 and predicted the spatiotemporal distribution of the small pelagic fish community. Then, I used biologging (GPS and dive loggers) of two diving seabirds, common guillemot (Uria aalge) and razorbills (Alca torda), to investigate their responses to diel distribution patterns of prey and found that their niche partitioning could be traced to divergent responses to prey distribution patterns and sensitivity to light levels. I further showed how common guillemots were dependent on predictable and stable foraging sites, but with clear responses in distance moved based on prey abundance and depth of site indicating active search. I finally zoomed out to the world’s seabirds and demonstrated how species-specific potential foraging range could be predicted by morphometrics and flying mode. This relationship was used to conclude that only 1% of the global seabirds’ foraging habitats during their breeding season are fully protected. By developing new methods and linking fine-scale behavioural responses to prey with broad-scale, trait-based conservation frameworks, this thesis provides a multiscale perspective on how foraging ecology in predators relates to marine ecosystems and prey fields. Such insights can inform biologically grounded conservation strategies for wide-ranging marine predators in a rapidly changing ocean.

Keywords

Predator-prey; spatiotemporal distribution; hydroacoustics; biologging; niche; diel behaviour; foraging behaviour; conservation; predator-bytesdjur; spatiotemporal distribution; hydroakustik; biologgning; nisch; dielt beteende; födosöksbeteende; bevarande

Published in

Acta Universitatis Agriculturae Sueciae
2025, number: 2025:32
Publisher: Swedish University of Agricultural Sciences

SLU Authors

UKÄ Subject classification

Ecology

Publication identifier

  • DOI: https://doi.org/10.54612/a.2dpu51qvq6
  • ISBN: 978-91-8046-467-3
  • eISBN: 978-91-8046-517-5

Permanent link to this page (URI)

https://res.slu.se/id/publ/132972