Arils as Food of Tropical American Birds

In Costa Rica, 16 kinds of trees, lianas, and shrubs produce arillate seeds which are eaten by 95 species of birds.These are listed and compared with the birds that feed on the fruiting spikes of Cecropia trees and berries of the melastome Miconia trinervia.In the Valley of El General, on the Pacific slope of southern Costa Rica, arillate seeds and berries are most abundant early in the rainy season, from March to June or July, when most resident birds are nesting and northbound migrants are leaving or passing through.The oil-rich arils are a valuable resource for nesting birds, especially honeycreepers and certain woodpeckers, and they sustain the migrants.Vireos are especially fond of arils, and Sulphur-bellied Flycatchers were most numerous when certain arillate seeds were most abundant.Many species of birds take arils from the same tree or vine without serious competition.However, at certain trees with slowly opening pods, birds vie for the contents while largely neglecting other foods that are readily available.