An Australian Pelican Pelecanus conspicillatus benefits from the beating behaviour of a Pied Cormorant Phalacrocorax varius: a possible precursor to kleptoparasitism

Food parasitism on pelican species by many groups of birds, especially Larus and Sterna spp. is well known and documented. Although the Pelicanidae exhibit many behavioural and ecological traits known to facilitate parasitism, few accounts and studies of this feeding strategy by pelicans are known. The following report describes a series of inshore parasitic bouts by an Australian Pelican Pelicanus conspicillatus on a Pied Cormorant Phalacrocorax variusin Monkey Mia, Shark Bay, Western Australia. The pelican made no attempt to feed prior to the arrival of the cormorant and remained in association with the cormorant for well over a quarter of an hour. The observed behaviour was clearly one of interception of prey by the pelican, and not merely of capitalising on food which could not escape. Ecological and behavioural factors known to encourage parasitic behaviour, such as "beating", are discussed in relation to these observations, as is the possibility of this feeding association leading to kleptoparasitism, or food theft. Potential costs and benefits of this association for both species are briefly discussed, as is the possibility that the association was precipitated by the protection afforded by the physical presence of humans and their structures.

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