On the behaviour in an alarm-evoking, constant stimulus situation in a „natural experiment“.—Observations on a pair of Herring Gulls(Larus argentatus) and Common Terns(Sterna hirundo) breeding on the same islet

Abstract

The behaviour of a pair of herring gulls nesting in a colony of common terns and the reactions of the terns towards the gulls have been observed for eleven days. The terns were found to be highly aggressive to an adult gull flying in an area of about 150×150 meters around the colony and this reaction did not decrease in intensity during the observation period.