Gelada
They are sometimes called the bleeding-heart monkey or the gelada baboon. They are large and robust. It is covered with buff to dark brown, coarse hair and has a dark face with pale eyelids. Its arms and feet are nearly black. Its short tail ends in a tuft of hair. Adult males have a long, heavy cape of hair on their backs. The gelada has a hairless face with a short muzzle that looks more similar to a chimpanzee's than a baboon's. It can also be physically distinguished from a baboon by the bright patch of skin on its chest.
This patch is hourglass-shaped. On males, it is bright red and surrounded by white hair; on females, it is far less pronounced. However, when in estrus, the female's patch will brighten, and a "necklace" of fluid-filled blisters forms on the patch. This is thought to be analogous to the swollen buttocks common to most baboons experiencing estrus. In addition, females have knobs of skin around their patches. Geladas also have well developed ischial callosities. There is sexual dimorphism in this species: males average 18.5 kg while females are smaller, averaging 11 kg. The head and body length of this species is 50–75 cm for both sexes. Tail length is 30–50 cm. The gelada has several adaptations for its terrestrial and graminivorous (grass-eating) lifestyle. It has small, sturdy fingers adapted for pulling grass and narrow, small incisors adapted for chewing it. The gelada has a unique gait, known as the shuffle gait, that it uses when feeding. It squats bipedally and moves by sliding its feet without changing its posture. Because of this gait, the gelada's rump is hidden beneath and so unavailable for display; its bright red chest patch is visible, though. There are two subspecies; the northern gelada, and the Eastern gelada, southern gelada or Heuglin's gelada
Habitat
Geladas are found only in the high grassland of the deep gorges of the central Ethiopian plateau. They live in elevations 1,800–4,400 m (5,900–14,400 ft) above sea level, using the cliffs for sleeping and montane grasslands for foraging. These grasslands have widely spaced trees and also contain bushes and dense thickets. The highland areas where they live tend to be cooler and less arid than lowlands areas. Thus, the geladas usually do not experience the negative effects that the dry season has on food availability. Nevertheless, in some areas, they do experience frost in the dry season, as well as hailstorms in the wet season.
Diet
Geladas are the only primates that are primarily graminivores and grazers – grass blades make up to 90% of their diet. They eat both the blades and the seeds of grasses. When both blades and seeds are available, geladas prefer the seeds. They eat flowers, rhizomes and roots when available, using their hands to dig for the latter two. They consume herbs, small plants, fruits, creepers, bushes and thistles. Insects can be eaten, but only rarely and only if they can easily be obtained. During the dry season, grasses are eaten less and herbs are preferred. Geladas consume their food more like ungulates than primates, and they can chew their food as effectively as zebra.
Breeding
When in estrus, the female points her posterior towards a male and raises it, moving her tail to one side. The male then approaches the female and inspects her chest and genital areas. A female will copulate up to five times per day, usually around midday. Breeding and reproduction can occur at any time of the year, although some areas have birth peaks. Most births occur at night. Newborn infants have red faces and closed eyes, and they are covered in black hair. On average, newborn infants weigh 464 g.
If a new male assumes mastery of a harem, females impregnated by the previous leader have an 80% likelihood of aborting. This phenomenon is known as the Bruce effect. Females come into estrus quickly after giving birth, so males have little incentive for practising infanticide, although it does occur in some communities in the Arsi region of Ethiopia, which may be an incentive for females to abort and avoid investing caring for an infant that will most likely be killed. It has been proposed the females who cancel their pregnancy can bond with the new leader faster. When a male loses his position as dominant harem-master, the females and new leader may allow him to remain in the social unit as a non-breeding resident who acts as a babysitter. This way the ex-leader can protect any infants he had fathered from being killed by the new leader, the females can protect the infants they had fathered from him, and when the new leader faces a potential rival, the ex-leader will be more inclined to help support him in keeping rivals at bay. Females that have just given birth stay on the periphery of the reproductive unit. Other adult females may take an interest in the infants and even kidnap them. An infant is carried on its mother's belly for the first five weeks, and thereafter on her back. Infants can move independently at around five months old. A subordinate male in a reproductive unit may help care for an infant when it is six months old. When herds form, juveniles and infants may gather into playgroups of around ten individuals. When males reach puberty, they gather into unstable groups independent of the reproductive units. Females sexually mature at around three years but do not give birth for another year. Males reach puberty at about four or five years, but they are usually unable to reproduce because of social constraints and wait until they are about eight to ten years old. Average life span in the wild is 15 years.
Population
Geladas are widespread throughout much of their present range, although they are probably not as abundant as they were in the 1970s when an aerial survey of the central Ethiopian Highlands yielded a population estimate of 440,000 individuals. A concurrent alternative estimate based on known ground densities from a small proportion of the Gelada’s geographic range and the total area of gorge face on the plateau yielded a figure of 884,000. Detailed ground surveys at five sites yielded overall densities varying between 15-69 animals/km², although densities of animals within their home ranges typically reached 70–80/km². A recent estimate for what is believed to be the largest remaining population of Geladas, in and around Simien Mountains National Park, was ~4,300 individuals, down from ~10,000 individuals in the 1970s.
Threats
The overall range of the Gelada is being eroded by agricultural expansion resulting from rapid human population growth in the Ethiopian highlands. Conversion of Gelada habitat to farmland and livestock grazing is common and soil erosion is a serious problem throughout the region. Grazing pressure is intense, and competition from domestic livestock has forced the Gelada to remain on the less productive gorge slopes in some areas. Gelada densities are considerably lower in heavily populated areas than in undisturbed habitats. Geladas are also harassed, shot or hunted with dogs as crop pests and occasionally sold locally as pets. In the past, Geladas were trapped for zoos though this practice no longer occurs. Also, in the past, adult male numbers were reduced as a result of selective shooting for their capes of hair, which were made into ceremonial costumes used by the Oromo people. The extent of this practice today is unknown. There are also historical records of Gelada capes being made into fur hats for tourists.
Government-sanctioned trophy hunting of Geladas by tourists is currently allowed in controlled hunting areas, although the extent and impact of this practice are unknown.
Parasitic swellings caused by tapeworms are a major cause of death in some Gelada populations.
Climate change poses a long-term threat to Geladas, especially for populations inhabiting higher elevations, where agriculture has previously been impossible or uncommon.
Conservation
This species is listed on Appendix II of CITES and as Class A under the African Convention.
Approximately 4,300 Geladas inhabit Simien Mountains National Park (a UNESCO World Heritage Site) in Begemdir, representing what is believed to be the largest remaining population. Geladas are also formally protected in the recently established Borena Sayint National Park, South Wollo, and they receive local protection in several community conservation areas (e.g., Guassa, North Shoa and Abune Yosef, North Wollo). It is recommended that formal protection be given to the Wabi Shebelle and Robe Gorges which are occupied by the unique Geladas that occur east of the Rift Valley. There is also an urgent need for further research to resolve the intraspecific taxonomy of Geladas, determine the remaining population numbers and distributions of the different subspecies, and identify the most important locations for Gelada conservation.