Foraging in a dynamic environment: response of four sympatric sub-Antarctic albatross species to interannual environmental variability

Seasonal and annual climate variations are linked to fluctuations in the abundance and distribution of resources, posing a significant challenge to animals that need to adjust their foraging behaviour accordingly. Particularly during adverse conditions, and while energetically constrained when breeding, animals ideally need to be flexible in their foraging behaviour. Such behavioural plasticity may separate 'winners' from 'losers' in light of rapid environmental changes due to climate change. Here, the foraging behaviour of four sub-Antarctic albatross species was investigated from 2015/16 to 2017/18, a period characterized by pronounced environmental variability. Over three breeding seasons on Marion Island, Prince Edward Archipelago, incubating wandering (WA, Diomedea exulans; n=45), grey-headed (GHA, Thalassarche chrysostoma; n=26), sooty (SA, Phoebetria fusca; n=23) and light-mantled (LMSA, P. palpebrata; n=22) albatrosses were tracked with GPS loggers. The response of birds to environmental variability was investigated by quantifying inter-annual changes in their foraging behaviour along two axes: spatial distribution, using kernel density analysis, and foraging habitat preference, using generalized additive mixed models and Bayesian mixed models. All four species were shown to respond behaviourally to environmental variability, but with substantial differences in their foraging strategies. WA was most general in its habitat use defined by sea surface height, eddy kinetic energy, wind speed, ocean floor slope and sea level anomaly, with individuals foraging in a range of habitats. In contrast, the three smaller albatrosses exploited two main foraging habitats, with habitat use varying between years. Generalist habitat use by WA and inter-annually variable use of habitats by GHA, SA and LMSA would likely offer these species some resilience to predicted changes in climate such as warming seas and strengthening of westerly winds. However, future investigations need to consider other life history stages coupled with demographic studies, to better understand the link between behavioural plasticity and population responses.All locations on land have been removed. Funding provided by: National Research Foundation South Africa*Crossref Funder Registry ID: Award Number: SNA093071Funding provided by: National Research Foundation South AfricaCrossref Funder Registry ID: Award Number: SNA093071Over three consecutive breeding seasons (2015/16, 2016/17 and 2017/18), GPS data loggers (CatLog-S GPS loggers, Perthold Engineering LLC USA, 50×22×8 mm, 34 g) were deployed on four albatross species on Marion Island during the incubation period (46°55' S; 37°40' E): wandering, grey-headed, sooty and light-mantled albatrosses. Loggers recorded locations at one-hour interval and were retrieved after one foraging trip