Mascarene High Variability Shapes the Demography of a Wind-Reliant Marine Top Predator

Subtropical anticyclones are semi-permanent atmospheric high-pressure systems located in all five major ocean basins and are associated with large-scale wind and weather patterns. They shape the physical environments of many species, yet their impacts on wildlife remain unexplored. We combined population and climate analyses to investigate the demographic effects of the Mascarene High, the Southern Indian Ocean subtropical anticyclone, on a wind-reliant marine top predator. Using 39 years of population data for wandering albatrosses (Diomedea exulans) breeding in the Southern Indian Ocean, we explored the mechanisms linking variability in the subtropical anticyclone to demographic rates. We found that an intensified and poleward-shifted Mascarene High toward Antarctica enhances westerly winds, increasing survival and reproduction probability across all life stages of wandering albatrosses. These findings uncover a direct link between subtropical anticyclones and population dynamics, highlighting subtropical anticyclones as important drivers of the responses of wind-reliant taxa to climate variability and change.