Buffy-headed marmoset

The buffy-headed marmoset (Callithrix flaviceps) is a rare marmoset endemic to the rainforests of south-eastern Brazil. It occurs in southern Espírito Santo and possibly northern Rio de Janeiro, and its distribution extends into Minas Gerais. Adults vary widely in weight, from roughly 119 to 710 grams, and the species has a low metabolic rate and an enlarged cecum that lets it digest food high in fibre. Because of its small size it is exposed to many predators, among them ocelots, green anacondas, hawks and toucans. It answers danger with a graded set of responses: soft closed-mouth whistles warn of distant aerial predators, louder open whistles send the group into cover, and against snakes or larger ground predators such as the tayra the group gathers to mob the intruder with calls. Separate calls are used within the group and between groups, and special calls announce a find of food.