By Martin Perrow, Andrew Harwood, Richard Berridge, Brian Burke, Stephen Newton and Daniel Piec
Abstract Rockabill, in Co. Dublin, supports the most important colony of Roseate Terns Sterna dougallii in Europe, testament to intense conservation effort over the last 30 years. This paper describes the first boat-based visual tracking of Roseate Terns from Rockabill and relates this to observations of chick provisioning at the colony. Roseate Terns are capable of rapid flight and routinely forage up to 30 km from the colony. Characteristic ‘power-diving’ from a relatively low height allows birds to reach greater depths than similar-sized terns, offering a competitive advantage, especially in deep, clear, oceanic waters. Birds are drawn to foraging auks, which bring schooling ‘bait-fish’ to the surface, but Roseates seem to be outcompeted by other species, especially Common Terns S. hirundo, in the ensuing melee and may be more successful foraging alone. Adult Roseates from Rockabill fed mainly on small fish (<3 cm in length) but carried larger clupeids or sandeels to provision chicks. Further work is needed to test the idea that a local stock of Atlantic Herring may be of fundamental importance to the success of the Rockabill colony.
To read the issue in full, you can subscribe to BB here