Forest Biology Lab.

　Feeding preference of the Velvet Asity, Philepitta castanea was examined in relation to fruiting phenology and a variety of fruit characteristics (nutritive and energy contents, colour, size, weight seed load, handling time and passage time) in Ranomafana rain forest, southeastern Madagascar, during the dry season (August-October).
　In the period when total fruit supply exceeded birds’energy requirement, fruit preference was obvious an stable, that is, fruits of Oncostemon leprosum (Myrsinaceae) were preferred, and those of Psychotria spp (Rubiaceae) were taken at random without preference, and those of Saldinia sp. (Rubiaceae) were avoided. But we did not find a preference among fruits, as predicted in optimal foraging theory, when total fruit supply was in short. There was no direct correspondence between the Velvet Asity preference and any other characteristics for selection.
　Assuming that frugivorous birds have a fixed criterion of fruit characteristics for selection, the fruits of Saldinia sp. might be avoided because the criteria on nutrition and/or energy were not filled (suggested by lowest values in percent of the nutrition assimilated, energy/handling time and energy/pulp weight). Foraging the large-sized fruits of Psychotria sp.8 with some favorable properties was perhaps limited by gape size. The fruits of O. leprosum may have been preferred due to the higher pulp-to-seed ratio and the shorter seed passage time resulting in higher food processing rate than Psychotria spp.