About the GeladaGelada monkeys live only in the high mountain meadows of Ethiopia—an environment very unlike those of their forest- or savanna-dwelling primate relatives. This high-altitude homeland is replete with steep, rocky cliffs. With their short and stumpy fingers, geladas are adept rock climbers. At night, the animals drop over precipice edges to sleep huddled together on ledges. Life on the GroundThese baboon-size animals are the world's most terrestrial primates—except for humans. As mostly grass-eaters, they are the last surviving species of ancient grazing primates that were once numerous. Geladas spend most of their day sitting down, plucking and munching on grasses and herbs. They have fatty sitting pads on their rear ends, which seem well adapted to this activity. Geladas live in multi-level societies. The smallest is that of the family, a stable unit of one male or a few males, two to ten females and their dependent offspring. Family units combine to form bands that travel together during the day. Sometimes geladas sill form large herds of up to 1200 individuals. These are some of the largest groups observed among any primate. Geladas can form such large groups because they feed mostly on grass, which is widely available. Gelada males are larger and hairier than females. The leader male is dominant to all other members of his family unit, but is eventually replaced by a younger rival. The fights during these replacements can be vicious and noisy. A strict dominance hierarchy exists among the females in a family unit as well. Aerial surveys suggested that 500,000 geladas existed in Ethiopia in the 1970s. Since then geladas have been increasingly exposed to the effects of encroaching agriculture and development, threatening the grasslands they inhabit. Surveys are currently under way to determine how many geladas still survive today.