Fig. 1. Distribution of fruit chromaticities from the diet of Ateles geoffroyi for red–green (RG) and yellow–blue (YB) colour vision signals, as defined in the text. Values are calculated for cone sensitivities of the standard catarrhine type of trichromatic colour vision with 535 and 562 nm pigments. Green circles represent the background (i.e. mature leaves), red circles represent fruits consumed by spider monkeys (N=39 species, representing more than 77.5% of feeding time in fruits). Red circles with pink dots represent the fruit species also eaten by males. The five most important species in the diet of A. geoffroyi are marked with squares and have the species names beside them. Whiskers represent standard errors of fruit chromaticities.