Consistent foraging habitat use by a vulnerable breeding seabird highlights potential areas for protection in the mid-Atlantic Ocean

Abstract

Identifying animal foraging habitat can help prioritise areas for conservation and enable better predictions of how populations respond to environmental change. Recent reductions in the size of biologging devices now enable fine-scale foraging habitat tracking for very small seabirds. We investigated the foraging distribution and habitat preferences of Monteiro’s storm-petrel Hydrobates monteiroi, a tiny (<60 g), vulnerable seabird that is endemic to the Azores Archipelago. We tracked 67 storm-petrels with 108 GPS deployments across 4 consecutive breeding seasons (2018-2021) to identify important foraging areas and preferences for dynamic and static features of their mid-ocean environment. We found that static bathymetric features such as seafloor depth and distance from the nearest seamount were the most important predictors of foraging location, suggesting that topographic features may provide areas of enhanced biological productivity in the mid-Atlantic Ocean that are predictable across long timescales. Although dynamic oceanographic variables (sea surface temperature and chlorophyll a) also helped predict foraging activity, both the location and environmental characteristics of foraging habitat were relatively stable across 4 consecutive years. This suggests that meso-scale oceanographic dynamics do not drive strong interannual variation in foraging behaviour in this system. Currently, only 11.4% of Monteiro’s storm-petrel foraging locations overlap with designated marine protected areas. A total of 95% of unprotected foraging locations fell within the Azores exclusive economic zone (EEZ), indicating a responsibility of the Portuguese government to increase habitat protection. Our findings suggest that more comprehensive at-sea conservation for this vulnerable species could be focused in predictable geographic areas over the mid-Atlantic ridge and seamounts.