Bats are assumed not to use vision for communication, despite recent evidence of their capacity for color vision. The possibility that bats use color traits as signals has thus been overlooked. Some tent-roosting bats have a potential for visual signaling because they exhibit bright yellow skin, a trait that in birds often acts as a sexual signal. The authors searched for evidence of sexual dichromatism in the yellow bare skin of Honduran white bats Ectophylla alba.

Colourful plumage is typical of males in species with conventional sex roles, in which females care for offspring and males compete for females, as well as in many monogamous species in which both sexes care for offspring. Reversed sexual dichromatism—more colourful females than males—is predominant in species with sex role reversal. In the latter species, males care for offspring and females compete for mates, the mating system is mainly polyandrous and there is reversed size...

Melanins are the most common pigments providing coloration in the plumage and bare skin of birds and other vertebrates. Numerous species are dichromatic in the adult or definitive plumage, but the direction of this type of sexual dichromatism (i.e., whether one sex tends to be darker than the other ones) has not been thoroughly investigated. Using color plates, the presence of melanin-based color patches in 666 species belonging to 69 families regularly breeding in the Western Palearctic was...

Human populations and breeds of domestic animals are composed of individuals with a multiplicity of eye (= iris) colorations. Some wild birds and mammals may have intraspecific eye color variability, but this variation seems to be due to the developmental stage of the individual, its breeding status, and/or sexual dimorphism. In other words, eye colour tends to be a species-specific trait in wild animals, and the exceptions are species in which individuals of the same age group or gender all...