Abstract:
Grey-headed albatrosses Thalassarche chrysostoma are listed as endangered on the IUCN Red List. Key threats include incidental bycatch in fisheries, climate change and predation at their breeding colonies. Globally their numbers are declining, but the population at sub-Antarctic Marion Island, the larger of the Prince Edward Islands, comprising 7 % of the global population, is currently considered stable. Though most of their life is spent at sea, little is known about where they go. At Marion Island, I investigated their year-round foraging during the breeding and non-breeding seasons in relation to environmental variables, marine protected areas and longline fishing effort. I tracked foraging trips of breeding greyheaded albatrosses during four years between 2012 and 2017 using GPS loggers, and recorded their year-round distribution from 2002 to 2005 and 2012 to 2016, using light-level Geolocation Sensors (GLSs.. I found that during the breeding season adults take much shorter trips (both in distance and duration. to waters over the South West Indian Ridge, an area of high productivity due to upwelling, whereas trips during incubation are much more wide-ranging and longer in duration, extending east and west of the island. During the non-breeding season, several migration strategies are observed – either remaining near the island; going east or west; or circumnavigating the Southern Ocean. Several core use areas were also identified. More wide-ranging trips, during both seasons, also mean that birds spend most of their time outside of Marine Protected Areas and in the high seas where they are more at risk to incidental bycatch in fisheries. As long-lived and wide-ranging predators, they are indicators of global ocean health and shifts in climate. Thus obtaining accurate descriptions of their distribution and at-sea habitat selection are essential in both contributing to their conservation as well as giving insight into global climate change. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
