On Monday 12 June, we put our first GPS loggers on to incubating Sooty Terns on Bird Island, for a third season of investigating where Seychelles Sooty Terns feed at this stage of their breeding season. These small loggers, made by Pathtrack Ltd (www.pathtrack.co.uk) weigh about three grams and we put them on to incubating birds that weigh a minimum of 180 grams. They are attached to the lower back of the birds using a flexible elastic harness that is held around the base of the thighs, a system that we have developed and which appears ideally suited to Sooty Terns. Each logger has a small battery that is charged by tiny solar panels. The loggers record GPS locations at fixed time intervals and the stored data are downloaded when we recapture the marked birds.
Today, 15 June, we recaptured our first marked bird of 2017 and the Google Earth map shows where the bird went during its 38 hours away from the nesting colony. It travelled west from Bird Island. following the northern boundary of the shallow Seychelles Bank. And eventually spent most of its feeding time (where the yellow markers are concentrated) where the Bank drops off over deep water, about 170 km from Bird Island.
Data of this kind will continue to be gathered as the breeding season progresses, providing an overview of feeding areas used by Sooty Terns. It is hoped that these data will be used to determine marine areas of importance to Seychelles seabirds and thereby identify areas that should be protected to preserve the archipelago’s marine biodiversity.