Foraging Ecology of the Hawaiian Crow, an Endangered Generalist

Abstract

The hypothesis that food was limiting the population of the endangered Hawaiian Crow (Corvus hawaiiensis) was investigated by observing its foraging habits. This crow was an omnivore, feeding on a wide variety of items including fruits, invertebrates, flower nectar, mammals, plant parts, and passerine eggs and nestlings. It was also an opportunistic feeder, shifting to readily available resources. The crow was adept at finding passerine nests, using this high protein diet of nestlings and eggs during the passerine breeding season. Oha kepau (Clermontia spp.) and olapa (Cheirodendron trigynum) comprised the bulk of the fruits taken. Arachnida and Isopoda were the predominant invertebrates found in droppings. Crows used the upper half of the canopy of mature trees, especially ohia (Metrosideros collina) and koa (Acacia koa), for their daily activities. Although the sample size was small, in the study area food seemed to be reasonably plentiful, and the crows were adaptable. Therefore, other factors probably are restricting the population. Efforts to maintain present habitat of the Hawaiian Crow need to be increased, with emphasis on ensuring a temporally continuous source of food.