Current wintering habitat of an endemic seabird of Réunion Island, Barau’s petrel Pterodroma baraui, and predicted changes induced by global warming

The impacts of global climate change on marine ecosystems are of increasing concern. Because of their restricted distribution, endemic organisms are especially sensitive. In this context, we investigated the impact of climate change on the wintering habitats of Barau’s petrel Pterodroma baraui, an Endangered endemic species of Réunion Island (western Indian Ocean). Birds were tracked with Global Location Sensing loggers, over 3 different years. We built suitability models to determine the environmental drivers that influence habitat selection. These models were then used to predict changes in the location and size of the wintering habitats in 2100. After breeding, Barau’s petrels consistently migrate eastward to a large oceanic area in the central and eastern Indian Ocean (centred on the Ninety East Ridge). Three main factors best predicted the presence of wintering Barau’s petrels: surface wind speed, sea surface temperature and chlorophyll a concentration. Adult Barau’s petrels tended to select cool, oligotrophic areas with stronger than average winds. Based on these variables, we identified 3 distinct areas of high suitability. This suitable habitat is predicted to shift westward and southward in the future, as a consequence of global warming, and the surface of total suitable habitat for wintering Barau’s petrels may be reduced by an average of 11% by the year 2100. These predictions are discussed in terms of biological conservation and adaptation to climate change. Our study is among the first to demonstrate the utility of using current tracking data and habitat modelling to predict the long-term effects of climate change on marine birds.