Gelada

The gelada is a monkey that lives only in the Ethiopian Highlands, at heights of 1,800 to 4,400 metres above sea level. It is sometimes called the bleeding-heart monkey because adult males have a bright red, hourglass-shaped patch of skin on the chest. Females have a bare patch too, but it is less striking.

Geladas spend much of their time on the ground, and they are the only living primates that live mainly on grass, which can make up as much as 90 percent of their diet. They have buff to dark brown hair, a dark face and pale eyelids. Males weigh about 18.5 kilograms on average and females about 11. They live in large, well-organised groups.

A big, layered society

Gelada society has several levels. The two basic groups are reproductive units and male units. When a reproductive unit has more than one male, only one of them mates with the females. Many units form a band, and one to four bands make up a community. Females in a unit are usually close relatives. Young males leave the group where they were born to try to take over a unit of their own, and the females can choose whether to support or oppose the newcomer. Geladas also use many different calls, and scientists think their range of sounds comes close to the complexity of human speech.

Are geladas in danger?

Their number is thought to have dropped from 440,000 in the 1970s to 200,000 in 2008. Even after such a big loss, the IUCN lists the species as Least Concern. Geladas are the only living member of the genus Theropithecus, a name that comes from Greek words meaning 'beast-ape'. Larger relatives lived in Africa, Europe and Asia in the past, and fossils have been found in many countries.

On the globe

The toy model of the gelada sits on the cliffs and grasslands of the Ethiopian Highlands. Look for the red patch on the chest.