Comparative foraging behaviour and efficiency of adult and juvenile great blue herons

Abstract

Foraging behaviour and efficiency of adult and newly fledged juvenile great blue herons, Ardea herodius L., were studied at the Gaspereau River estuary. Nova Scotia, in July and August 1977 and 1978. Pace and strike rates of adults and juveniles were similar, whereas capture and probe rates differed markedly. Adults captured prey more successfully than juveniles but the ability of the latter improved with age. Foraging success of adults was greater in flocks of more than five individuals. In contrast, juvenile success does not seem related to flock size. Ninety-eight percent of the identified prey were flounder Liopsetta putnmi Gill. Handling time of small prey items was the same for adults and juveniles but juveniles took much longer to swallow medium-sized prey than adults did.