Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Frontiers in Ecology and Evolution 1028317 [18 p.] habitat overlap distribution loggers movement ecology spatial ecology post-breeding segregation PACIFIQUE PACIFIQUE NORD 2022 fdi:010086731 ENG Frontiers in Ecology and Evolution 2296-701X ISI:000901963400001 10.3389/fevo.2022.1028317 https://www.documentation.ird.fr/hor/fdi:010086731 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2023-02/010086731.pdf 10 Horizon (IRD) Understanding the at-sea movements of wide-ranging seabird species throughout their annual cycle is essential for their conservation and management. Habitat use and resource partitioning of Laysan (Phoebastria immutabills) and black-footed (Phoebastria nigripes) albatross are well-described during the breeding period but are less understood during the post-breeding period, which represents similar to 40% of their annual cycle. Resource partitioning may be reduced during post-breeding, when birds are not constrained to return to the nest site regularly and can disperse to reduce competitive pressure. We assessed the degree of spatial segregation in the post-breeding distributions of Laysan (n=82) and black-footed albatrosses (n=61) using geolocator tags between 2008 and 2012 from two large breeding colonies in the Northwestern Hawaiian Islands, Midway Atoll, and Tern Island. We characterized the species-and colony-specific foraging and focal distributions (represented by the 95 and 50th density contours, respectively) and quantified segregation in at-sea habitat use between species and colonies. Laysan and black-footed albatross showed consistent and significant at-sea segregation in focal areas across colonies, indicating that resource partitioning persists during post-breeding. Within breeding colonies, segregation of foraging areas between the two species was more evident for birds breeding at Tern Island. Spatial segregation decreased as the post-breeding season progressed, when spatial distributions of both species became more dispersed. In contrast to studies conducted on breeding Laysan and black-footed albatross, we found that sea surface temperature distinguished post-breeding habitats of black-footed albatrosses between colonies, with black-footed albatrosses from Midway Atoll occurring in cooler waters (3.6 degrees C cooler on average). Our results reveal marked at-sea segregation between Laysan and black-footed albatross breeding at two colonies during a critical but understudied phase in their annual cycle. The observed variation in species-environment relationships underscores the importance of sampling multiple colonies and temporal periods to more thoroughly understand the spatial distributions of pelagic seabirds. 034 ; 080 ; 082 UR248