Geolocation and immersion loggers reveal adult red-footed boobies are year-round residents in the tropical Indian Ocean

Bio-logging has revealed much about high-latitude seabird migratory strategies, but tropical species are comparatively understudied. Here we use geolocators to study the year-round movement behaviour of adult red-footed boobies ( Sula sula rubripes ) from the Chagos Archipelago, tropical Indian Ocean. Light levels suggest that red-footed boobies are resident in the archipelago year-round, although there are large latitudinal errors this close to the equator. However, immersion data revealed tracked birds returned to land year-round, with no extended at-sea periods, further indicating this population is non-migratory. Our findings have important implications for seabird conservation and phylogenetics, as well as for assessing the impact of seabird nutrients on coral reef ecosystems.