Inter- and intra-specific kleptoparasitism at a mixed-species colony of Royal (Sterna maxima) and Cayenne terns (S. eurygnatha)

Abstract

Within seabirds, terns are frequently affected by foodrobbing. We document the occurrence of kleptoparasitism at a mixed-species colony of Royal (Sterna maxima) and Cayenne (S. eurygnatha) terns at Punta León, Chubut. In two seasons we observed both inter- and intra-specific food robbing by adult terns. The amount of food lost to pirates was relatively low, only 2% of prey brought back by the terns (n = 1127). Intraspecific food robbing was higher than interspecific kleptoparasitism in the Royal Tern and similar in the Cayenne Tern. The percentage of food lost to pirates in the colony (2.1%,n = 921) was similar than in groups of tern chicks at the beach (2.4%, n = 206). Kleptoparasitism between terns at Punta León appears to be of little importance with respect to its effects on both tern populations.