| Summary: | Long-lived species exhibit a slow adaptation through natural selection and should rather adapt to rapid environmental changes through phenotypic plasticity, e.g. by showing behavioural changes. The degree to which species can adapt by phenotypic plasticity appears particularly critical for survival of a species in times of global climate change and other anthropogenic threats. In the framework of my PhD, I studied the reactions of southern rockhopper penguins (Eudyptes chrysocome) in response to environmental variability in terms of physiology, foraging behaviour and survival. Southern rockhopper penguins should be limited in their phenotypic plasticity compared to other species, as they are less mobile than flying seabirds and as they are feeding on low trophic level prey. These characteristics should make them more susceptible to changes in the food web. Populations of southern rockhopper penguins worldwide have declined dramatically in recent decades, and reasons for these declines remain unclear yet might be related to on-going climate changes. The southern rockhopper penguins' Subantarctic marine habitat is particularly affected by global climate change through an increase in sea surface temperatures (SST), and will likely experience changes in the wind regime, as the southern ocean west wind drift shifts polewards. How will southern rockhopper penguins react to such changes in their environment, which go beyond current environmental variability, in the future? To answer this question, I first studied the species' adaptations to its current environment, before focussing on the birds' reactions in foraging behaviour and survival to occuring environmental variability. Given that southern rockhopper penguins should be limited in their phenotypic plasticity, I expected them to show strong adaptations to their current environment and hypothesized that enhanced environmental variability negatively affects foraging behaviour and survival. My results indicate that southern rockhopper penguins are physiologically ...
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