Document Type


Date of Original Version



We studied the ecology of the endangered Hawaiian Hawk (Buteo solitarius) on the island of Hawaii for three breeding seasons. Their breeding strategy is a prime example of a K-selected species characteristic of many birds in tropical environments: clutch size was one and brood-rearing was among the longest reported for any diurnal raptor. Twenty-eight nests were found in a variety of native and exotic habitats. Incubation lasted 38 days, nestlings fledged after 59-63 days, and parents cared for fledglings for an average of 30.2 weeks, which was 2.5 to 10 times longer than similar-size temperate zone raptors. Males assisted females with incubation, but only females brooded young. Radio-tagged juveniles remained within 0.63 km of their nests for the first two months after fledging, after which dispersal distances expanded gradually. Avian (45%) and mammalian (54%) prey dominated the diet of nestlings. There was no evidence that avian malaria, introduced predators, or environmental contaminants were affecting their population. Based upon estimates of population size, the availability of suitable nesting habitat, and reproductive success, we suggest the species be considered for downlisting from endangered to threatened status.

Publisher Statement

© 1998 by the Regents of the University of California/Cooper Ornithological Society. Copying and permissions notice: Authorization to copy this content beyond fair use (as specified in Sections 107 and 108 of the U. S. Copyright Law) for internal or personal use, or the internal or personal use of specific clients, is granted by the Regents of the University of California on behalf of the Cooper Ornithological Society for libraries and other users, provided that they are registered with and pay the specified fee via Rightslink® on [JSTOR (] or directly with the Copyright Clearance Center,