A Case of Female Usurpation in the Australian Pied Oystercatcher Haematopus longirostris

Abstract

This note documents a prolonged and eventually successful territory usurpation experienced by a long-term breeding pair of Australian Pied Oystercatchers Haematopus longirostris. The disruption was caused by a novice female breeder and initially led to a temporary, apparently non-breeding, trio formation. Unusual aspects of the event are discussed and compared with known usurpation and divorce behaviour in this species and in the Eurasian Oystercatcher H. ostralegus.