| Summary: | Recent improvements in biotelemetry and analytical methods have increased our understanding of the at-sea movements and behaviour of elusive pelagic seabirds, many of which are becoming the focus of conservation efforts. In this thesis, I consider several issues related to the environmental correlates of the foraging movements and at-sea distributions of a critically endangered shearwater in UK waters and of two penguin species in Antarctic and sub-Antarctic waters; I also consider the use of the ‘dual foraging strategy’ (i.e., both short- and long-distance foraging) during chick-rearing of different seabird taxa. This thesis explores the associations of oceanographic variables and prey abundance with the at-sea distribution of both non-breeding seabirds (Balearic shearwater Puffinus mauretanicus, Chapter 2) and of breeding seabirds (macaroni penguins Eudyptes chrysolophus, Chapter 4). Chapter 2 combines 5 years of vessel-based surveys of post-breeding Balearic Shearwaters in the western English Channel and southern Celtic Sea with simultaneously collected bio-acoustics data of fish abundances and remote-sensed environmental data. I map Balearic shearwater presence across the area using both Generalized Additive Models (GAMs) and Random Forest (RF) models, providing the first estimate of the distribution of this critically endangered seabird in UK waters, information that is essential for the designation of a Special Protection Area (SPA). Oceanic variables associated with prey distributions were better predictors of seabird movements than direct measures of prey distribution, possibly because snapshots of prey availability cannot capture the dynamic nature of prey distributions. Using data from GPS and time-depth recorders, this thesis also investigates the presence and dynamic nature of prey depletion around breeding colonies in two penguin species (chinstrap penguins Pygoscelis antarcticus in Chapter 3, and macaroni penguins in Chapter 4) and estimates foraging patch quality based on time allocation during ...
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