Comparison of the Diets of Nestling Cattle Egrets and Intermediate Egrets in the Hunter Valley, New-South-Wales

摘要

The foods of Ardeola ibis coromandus and Egretta intermedia plumijera were determined from boluses regurgitated by chicks. There were 61 boluses collected from A. ibis and 33 from E. intermedia over four breeding seasons. A. ibis ate orthopteran insects (66% bulk weight) with fewer vertebrates (23%). E. intermedia relied on vertebrates (69%), mainly fish (58%), but also ate orthopterans (22%). Each species was largely opportunistic in its feeding but probably selected different habitats in which to forage. From the small dietary overlap revealed in this study, we conclude that interspecific competition for food was unlikely during the 1985-1987 breeding seasons.