Climate oscillation and alien species invasion influences oceanic seabird distribution

Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at-sea observations of seabirds (n = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red-footed booby, brown noddy, white tern and wedge-tailed shearwater), geomorphology, oceanographic variability, and climate oscillation in the Chagos Archipelago. We documented positive relationships between red-footed booby and wedge-tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution respectively). The abundance of red-footed boobies, brown noddies and white terns declined abruptly with greater distance to island (17.6%, 34.1% and 41.1% contribution respectively). We further quantified the effects of proximity to rat-free and rat-invaded..., Data was collected by Peter Carr and one or two assistants between 2012-2016 in the Chagos Archipelago using transects with a duration of 30 minutes. During each transect, the vessel typically steamed at 12 knots and travelled ca. 11 km. Sightings were annotated within a 180 arc from the vessel out to ca. 300 m. Any detail of how environmental variables were collected, please see the main manuscript., ,