The feeding behavior of the Black Kite (Milvus migrans) in the rubbish dump of Rome

Abstract

We studied the feeding behavior of Black Kites (Milvus migrans) in a rubbish dump in Rome, Italy, from April-September 2005. The earliest kites reached the rubbish dump at dawn and the last left just after dusk. The number of individuals foraging in the dump increased during the course of the day and also from April to August. The number of kites in the rubbish area of the dump was usually small and tended to show rapid increases and equally quick declines. Kites searched for food while directly standing on the rubbish or, more often, while flying low over the ground. The first strategy, which was never observed in April but was more common during the following months, was used when there were few foraging gulls or trucks in the dump. Cleptoparasitism. was the technique most frequently used to acquire food (76% of all foraging events). It was directed toward conspecifics in 35% of the observed cases, toward Yellow-legged Gulls (Larus cachinnans) in 57% and toward Carrion Crows (Corvus corone) in 8%. The success rate of cleptoparasitic attempts was 32% against conspecifics, 73% against Yellow-legged Gulls and 66% against crows. The higher frequency of cleptoparasitic attempts against gulls may thus be explained by its higher success rate, although its efficiency declined with increasing gull numbers. The frequency of intraspecific cleptoparasitism paralleled variations in kite density and its effectiveness increased progressively from April-August. © 2008 The Raptor Research Foundation, Inc.