Use of sea ice by arctic terns Sterna paradisaea in Antarctica and impacts of climate change

Arctic Terns spend their breeding and non-breeding seasons in polar environments at opposite ends of the world. The sensitivity of polar regions to climate change makes it essential to understand the ecology of Arctic Terns but the remoteness of the Antarctic presents a considerable challenge. One solution is to use ‘biologgers’ to monitor remotely their behaviour and distribution in the Antarctic. Data from birds tagged with light-level global location sensors (geolocators) in 2015 and 2017 showed that a third of their annual cycle was spent amongst Antarctic sea ice. After reaching the East Antarctic in the austral spring, they gradually moved west, foraging in fragmented ice zones of the Antarctic coastline, leaving in the austral autumn for their return northward migration via the Atlantic. Changes in patterns of movement between phases of 24-h daylight and diel day/night conditions were likely linked to the annual moult, and stable isotope analyses suggest that krill (Euphausia spe...