Although often referred to as gelada baboons (Theropithecus gelada), these monkeys actually belong to a separate genus and are not true baboons. They are in fact the only member of their genus and the last surviving species of a once widespread group of grass-grazing primates. The gelada can be easily recognised by the unusual hairless patches of skin on the chest, which blaze a bright crimson colour when females are in oestrus. Since this species spends long periods sitting whilst foraging for food, the usual sexual cue of red sexual swellings around the genitals would be difficult to see. Thus, by mimicking these sexual swellings, these more conspicuous chest patches serve as a highly visible signal of sexual receptivity. The coat is short and brown with a tuft of hair at the tip of the tail, and the adult male’s shoulders are cloaked by a large cape-like mantle or mane. The muzzle is deeply grooved with longitudinal ridges, and the upper lip can be everted in flash displays of communication, just as the contrasting pale eyelids against the dark face are also used for communicative expression.
