Black-and-White Colobus

Colobus guereza

Colobus 300x200 Black and White ColobusSize:

Head and body length: Female 48 – 65 cm; Male 54 – 75 cm

Tail length: 65 – 90 cm

Weight: 10 – 23 kg [in Uganda, Males 9-14.5kg; Females 6.5 – 10 kg]

Description:

Distinctive, black-and-white monkey with a long, bushy white tail and white cheek hair. Long limbs, small head, four fingers on front hands. Has short, thin hair in lowland forests and longer, thicker hair in mountain areas.

Breeding:

Most young are born in the rainy season, after a gestation of about six months. The young are mostly white with pink faces until they are 14 – 17 weeks old. They are carried by females for up to 8 months, but are able to move on their own beginning at about 5 weeks. By four months they are playing and exploring on their own and are only carried when the whole troop is traveling. Mothers largely ignore their offspring by 23 – 25 weeks

Where to look for them:

When entering the park through either of the southern gates, it is possible to see these monkeys from your car, especially when there is forest canopy overhanging the road. You can increase your chances of seeing them by taking a forest walk at Busingiro, Kaniyo-Pabidi or Rabongo forests.

What to notice:

  • “Colobe”, the root of the name “Colobus” is Greek for “cripple.” This name derives from the fact that colobus monkeys do not have thumbs on their hands. They have evolved to be almost entirely arboreal (tree-dwelling), and their hands have developed into modified hooks for swinging on branches. A thumb would simply get in the way.
  • The lack of a thumb makes it difficult to catch live prey, so colobus monkeys have evolved to be far more vegetarian than most other primates. Their digestive systems have adapted to be almost like that of an antelope, allowing them to consume leaves and twigs that would be either too coarse, non-nutritious, or even toxic for other monkeys. They can take up to a third of their body-weight into their two-chambered stomachs where it is processed during the hours when they are asleep.
  • Chimpanzees prey on colobus monkeys where they co-exist, as they do in all of the forest areas in Murchison Falls Conservation Area.

Conservation Status:

They are not considered endangered, but their range has been seriously restricted by habitat loss and hunting. The mountain populations have very valuable pelts and may be hunted to extinction since there is no legal protection for them. Their pelts are also used for drum heads, and there are efforts to get drum makers to use the skins of black-and-white goats instead.

Detailed Information:

Order: Primates
Superfamily: Catarrhini
Family: Cercopithecoidea
Subfamily: Colobidae
Genus: Colobus
Species: guereza

General Description/Adaptations:

Distinctive, black-and-white monkey with a long, bushy white tail and white cheek hair. Long limbs, small head, four fingers on front hands. Has short, thin hair in lowland forests and longer, thicker hair in mountain areas. (Kingdon, p 26)

General info on monkeys:

The primates in Africa are all cercopithecoid monkeys except for humans, other great apes, and bushbabies. The cercopithecoid monkeys are divided into colobids (“thumbless monkeys”) and “cheek-pouch monkeys”, which are a more diverse grouping. The monkeys probably diverged from the great apes between 20 and 10 million years ago.

The colobids were able to exploit dense forest because of an ability to digest plant parts (stems, unripe fruits and leaves) that the apes were not able to consume (being largely restricted to shoots and ripe fruits). Cheek-pouch monkeys adapted to feeding in open areas – they are able to quickly gather large quantities of food, and store it in their cheek pouches to be sorted out later. Baboons are an example of this. Cheek-pouch monkeys are also likely to be more extremely sexually dimorphic, as the males compete aggressively for available food sources and are more visible in open areas. (Kingdon, p. 17)

Food:

The adaptation of the hands shows that they evolved to be wholly arboreal and wholly vegetarian at an early stage. The hands are modified into curved ‘hooks’ for swinging, and the lack of a thumb means they cannot grab live prey and so choose to take vegetation directly into their mouths. The pied colobus is more highly evolved that the red colobus, and so is able to subsist on lower-quality vegetation. This gives them an advantage. (Kingdon, p. 18)

The digestion of colobus monkeys has adapted in a similar way to the ruminants. They are able to hold 1/3 of their body weight in their stomachs, which is then processed during long sleeping and resting periods during the middle of the day. Digestion is assisted by bacterial fermentation, like ruminants and other herbivores. (Kingdon, p. 19)

They have a two-chambered stomach, with fermentation happening in one and then acid digestion in the other. The fermentation process also detoxifies leaves, seeds and fruit that would otherwise be poisonous. This allows them to feed with less competition from other primates. (Estes, p. 520)

Newborns are entirely white, with pink faces. (Estes, p. 523)

Communication:

Vocal:

(Estes, p.527)
Roaring: This is supposedly only emitted by dominant males, especially early in the morning. It is a low, resonant croaking sound with a rolling “r” that can be heard for over a mile. They may call like this for up to 20 minutes. It can be used either for advertising the male’s presence or as a threat display.

Snorting: Explosive sound, emitted by all except infants, to express alarm. Often a prelude to roaring for dominant male.

Snuffling: A sound like a pig rooting. Females and young will emit this sound during intra-troop conflict such as a female pushing away an infant that wants to nurse, or in aggressive interactions between females and males.

Squealing: Adult females and young emit this as a signal of strong distress.

Soft grunting or purring: Alert call for short-distance communication such as a signal for troop movement. May also signal a predator nearby.

Tongue-clicking: Adults use this as a prelude to an aggressive interaction. Milder than snorting.

Jumping around and crashing through branches may be used by dominant male to show size and strength. Sometimes joined with roaring. (Estes, p. 529)

Activity Patterns:

They spend the middle of the day almost totally inactive or asleep, like ruminants. (Kingdon, p. 17)

These monkeys leave their sleeping trees well after sunup, then proceed to the canopy where they sunbathe in sight of neighboring troops for up to an hour. They travel regular arboreal routes to get to their feeding trees, then feed until it gets hot. They will rest and groom until the evening, at which point there is another activity peak until about one hour before sunset, when they return to their sleeping trees. (Estes, p. 526)

Sign:

Look for the track of the hand with only four fingers.

Predators:

Chimps, humans, leopards, crowned hawk-eagles.

References:
Estes, R. (1991). The Behavior Guide to African Mammals. Berkeley, CA: The University of California Press.

Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. Princeton, NJ: Princeton University Press.

Photo by Charles Steinberg

Leave a Reply

%d bloggers like this: