Colobus Monkeys

Red colobus monkeys (genus Procolobus or Piliocolobus) live along the equator in Africa. They come in many different colors in addition to the reddish black that gives them their name. They often have whitish or grayish faces and chests, with the deep red color appearing only on their back, crown of the head, paws, and tip of the tail. This color variety has made these monkeys difficult to classify, and there is considerable disagreement in their grouping. Red colobus monkeys have a head and body length of 17.7-26.4 in (45-67 cm), a tail length of 20.5-31.5 in (52-80 cm), and weigh 11.2-24.9 lb (5.1-11.3 kg). These monkeys have no thumb at all, lacking even the small vestigial thumb seen in black and white colobus monkeys.

Red colobus monkeys are also arboreal. Most populations are found in rain forests, but they also inhabit savanna woodland, mangrove swamps, and floodplains. Red colobus monkeys also form stable groups, but the groups are much larger than those formed by black and white colobus monkeys-ranging in size from 12 to 82 with an average size of 50. These groups usually include several adult males and 1.5-3 times as many adult females. There is a dominance hierarchy within the group maintained by aggressive behavior, but rarely by physical fighting. Higher ranking individuals have priority access to food, space, and grooming.

Red colobus monkeys also seem to breed throughout the year. A single offspring is born after a gestation period of 4.5-5.5 months. The infant is cared for by the mother alone until it reaches 1-3.5 months old.

Most red colobus species are coming under increased pressure from timber harvesting. This activity not only destroys their rainforest habitat, but also makes them more accessible to hunters. At least one authority considers red colobus monkeys to be the easiest African monkeys to hunt. Several species and subspecies are considered endangered, vulnerable, or rare by international conservation organizations. For example, the Zanzibar red colobus (Procolobus kirkii) is seriously en dangered—in 1981 less than 1,500 animals were estimated to survive.

Grouped with the red colobus monkeys because of its four-chambered stomach is the olive colobus, Procolobus verus, of Sierra Leone and central Nigeria. This monkey is actually more gray than olive or red. Its head and body length is 16.9–35.4 in (43–90 cm) and it weighs 6.4–9.7 lb (2.9–4.4 kg). This species is also arboreal and is restricted to rainforests. It forms small groups of 10–15 individuals usually with more than one adult male in each group. In a practice unique among monkeys and apes, mothers of this species carry newborns in their mouths for the first several weeks of the infant's life. This species is threatened by intensive hunting and habitat destruction; it is considered vulnerable by IUCN—The World Conservation Union.