Habitat preference, accessibility, and competition limit the global distribution of breeding Black-browed albatrosses

• Published in: Ecological Monographs
• Main Authors: Wakefield, Ewan D., Phillips, Richard A., Trathan, Philip N., Arata, Javier, Gales, Rosemary, Huin, Nic, Robertson, Graham, Waugh, Susan M., Weimerskirch, Henri, Matthiopoulos, Jason
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2011
• Subjects: Sea ice
• Online Access: https://eprints.gla.ac.uk/72284/

Telemetry methods and remote sensing now make it possible to record the spatial usage of wide-ranging marine animals and the biophysical characteristics of their pelagic habitats. Furthermore, recent statistical advances mean that such data can be used to test ecological hypotheses and estimate species' distributions. Black-browed Albatrosses Thalassarche melanophrys are highly mobile marine predators with a circumpolar breeding and foraging distribution in the Southern Hemisphere. Although they remain relatively abundant, increased fisheries bycatch has led to their listing as endangered by conservation bodies. We satellite-tracked 163 breeding Black-browed Albatrosses and eight closely related Campbell Albatrosses T. impavida from nine colonies. We then quantified habitat usage, and modeled population-level spatial distribution at spatiotemporal scales > 50 km and 1 month, as a function of habitat accessibility, habitat preference, and intraspecific competition, using mixed-effects generalized additive models (GAMM). During incubation, birds foraged over a wider area than in the post-brood chick-rearing period, when they are more time constrained. Throughout breeding, the order of habitat preference of Black-browed Albatrosses was for neritic (0–500 m), shelf-break and upper shelf-slope (500–1000 m), and then oceanic (>1000 m) waters. Black-browed Albatrosses also preferred areas with steeper (> 3°) bathymetric relief and, in addition, during incubation, warmer sea surface temperatures (peak preference 16°C). Although this suggests specialization in neritic habitats, incubation-stage Black-browed Albatrosses from South Georgia also foraged extensively in oceanic waters, preferring areas with high eddy kinetic energy (> 250 cm 2 /s 2 ), especially the Brazil-Malvinas Confluence, a region of intense mesoscale turbulence. During chick-rearing, this species had a more southerly distribution, and following the seasonal retreat of sea ice, birds from some populations utilized neritic polar waters. ...