Migratory movements, distribution, habitat preference, and activity patterns of the endangered Abbott’s booby Papasula abbotti

ABSTRACT: The Abbott’s booby Papasula abbotti is one of the most threatened seabirds in the world. The non-breeding behaviour and distribution of Abbott’s boobies are largely unknown but evidence suggests they migrate between breeding attempts. This lack of information impedes the identification and quantification of the threats the birds are exposed to outside of their breeding season. We studied the migratory movements of Abbott’s booby using geolocator-immersion loggers. A total of 22 adult birds were tracked between 2007 and 2014. Analysis of the 27 migratory trips revealed that birds migrated on average 2500 km east of Christmas Island to an area centred around the Banda Sea, Indonesia. The timing of Abbott’s booby migration (from November-December to April) coincides with the Indonesian-Australian monsoon, a period characterised by reversing prevailing winds and decreased regional oceanic primary productivity. The birds’ movements matched the pattern of reversal of the prevailing winds. No birds were recorded on migration between 17 May and 26 October, which suggests that the whole population of adult Abbott’s boobies is on Christmas Island during that period. Migrating Abbott’s boobies spent little time on the water during the day or at night (15%), and individuals preferred waters with a narrow range of sea surface salinity (32.5-34.5 PSU), rugged seafloor topography, and sea surface temperatures above ca. 28°C. Overall, these novel results identify the area within which potential threats, such as interactions with fisheries or effects of climate change on the species’ marine habitats, should be investigated.