Geographic variation and subspecies of Corvus Enca (Horsfield, 1821)

In this paper a survey is given of the geographic variation and the subspecies of Corvus enca (Horsfield). For that purpose the collections of the Rijksmuseum van Natuurlijke Historie in Leiden and the Zoölogisch Museum in Amsterdam were studied and compared with the literature. My examinations resulted in the following division of subspecies: - Corvus enca compilator Richmond: Malaya, Sumatra, Simalur, Nias, Borneo, (Rhio Archipelago). - Corvus enca enca (Horsfield): Java, Bali, Celebes, Sula Islands, (Mentawei Islands). - Corvus enca violaceus Bonaparte: Ceram (and perhaps Buru). - The birds from Mindoro, Samar, Mindanao, Palawan, Balabac and Luzon possibly belong to two or three subspecies. Geographic variation also appears to exist among the populations of C. e. compilator of the various islands this subspecies inhabits. Besides geographic variation I found differences between the sexes as well: males have a larger bill and wing length than females.