Multi-decadal changes in the at-sea distribution and abundance of black-browed and light-mantled sooty albatrosses in the southwest Pacific Ocean

Abstract

Abstract Many long-term studies have reported changes in seabird abundance and distribution in response to climate change and various anthropogenic activities. However, a greater understanding of how species are responding to change over large spatial and temporal scales are required—particularly at high latitudes such as the Southern Ocean. We examined black-browed Thalassarche melanophris (BBAL) and light-mantled sooty Phoebetria palpebrata albatross (LMSA) observations spanning over 50 years. Both species have a wide-ranging distribution in a rapidly changing Southern Ocean. We used generalized additive models (GAMs) to investigate environmental drivers of their abundance and occurrence. Our results show that climate indices, sea surface temperature and sea surface height are the main drivers influencing the distribution and abundance of both species. The abundance of BBAL southeast of Australia was observed to be decreased substantially whereas no significant change was observed in the abundance of LMSA. Both species demonstrated contrasting distributions along their latitudinal gradient with BBAL showing early stages of a southward range shift. Our analyses suggest that responses to climate change are species-specific. These rare, long-term data have provided an understanding of species’ responses to past changes in the marine environment and can provide critical information for future conservation and management.