Kleptoparasitism in Tropical Seabirds: Vulnerability and Avoidance Responses of a Host Species, the Red-Footed Booby

Abstract

We investigated the importance of kleptoparasitism in a population of Red-footed Boobies (Sula sula) sympatric with frigatebirds (Great and Lesser Frigatebird Fregata minor and F. ariel) and identified the responses adopted by boobies. Less than 1% of the boobies lost their food by kleptoparasitism. Birds flying in a group >50 m high or after dusk were less likely to be chased than others. We compared the way boobies returned to land and the rate of successful chases in this population with another population of Red-footed Boobies where kleptoparasitic attempts were rare. Birds were more nocturnal in the former population and were better able to resist chases. These observations suggest that the coexistence of boobies with frigatebirds may have led to avoidance responses. Comparison of the behavior of the Masked Booby (Sula dactylatra) to that of the Red-footed Booby showed that the former should be more vulnerable when returning to land than the latter. Further investigations are needed on the way Masked Boobies interact with frigatebirds in a place where both coexist in large numbers and to determine if this species has adopted other avoidance tactics.