Bristle-thighed Curlews (Numenius tahitiensis) prefer to forage on rat-free islets at Rangiroa atoll, French Polynesia

Abstract

Among several threats, the food availability at stopover and wintering sites contributes to the decline of shorebird species. It is the case in the Pacific region, where the overwater journey for the migration is very long often without the possibility of landing. We deployed GPS tags on Bristle-thighed Curlews (Numenius tahitiensis) in their wintering site (Rangiroa-French Polynesia) to explore foraging habitat use in the context of the presence or absence of introduced rats, which could impact food availability for the birds. The tracking data and the habitat mapping effort allowed us to explore habitat selection and its variability between birds and activities. Curlews used preferentially rat-free islets during the day, when they forage and feed. This preference was not occurring at night, when the birds roost. This result suggests negative interactions mediated through the resources, such as the food competition between rats and curlews, rather than a direct negative interaction. Rat eradication appears as a potential conservation tool for the endangered Bristle-thighed Curlew, to allow access to appropriate food resources and efficient refueling before the spring migration.