Black-and-white Colobus (Colobus guereza)
Size:
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)
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)
Habitat:
Colobus monkeys
are restricted to the moist, tropical and montane forest belt. Cheek-pouch monkeys are much more widely
distributed and are found in all habitats except the Sahara,
although they attain the greatest diversity in forested areas. (Kingdon, p. 17)
‘Colobe’ is Greek
for ‘cripple’ – they were given this name due to the lack of thumbs. (Kingdon,
p. 18)
Pied colobus are
able to live in more degraded forests than red colobus due to their more
specialized digestive system. (Kingdon, p. 30)
In Kibale National
Park in Uganda, there is only a 7% overlap
in food species between the red and the black-and-white colobus. Even on these common species, they eat
different stages of growth. (Estes, p. 521)
Home Range:
Size varies from
about 5 hectares to about 25 hectares.
These territories have hard edges, and the small size allows for very
high concentrations of these monkeys, ranging up to 500/sq. km in Kenya and Tanzania. (Estes, p. 525)
Food/Water:
They are often
characterized as ‘leaf-eaters’, but actually eat a wide range of difficult
plant material, including seeds, seed pods, petioles, and unripe fruits, and
avoid fresh, colorful fruits. There are also able to process leguminous plants
that are poisonous to most other animals.
The Guereza pied colobus, in particular, is able to process hard, old
leaves which allows them to survive long dry seasons. (Kingdon, p. 18)
In Uganda, 40% of
the guereza’s food comes from one tree, Celtis
durandii. This is the only monkey
that eats the leaves of this tree, eliminating competition. Figs may also constitute up to 25% of their
diet at certain times of the year. (Estes, p. 524)
Breeding:
Six month
gestation. Births happen more often in
the rainy season, spaced about 20 months apart.
Females mature at 4 years, males at 6.
Infants are large at birth, but develop slowly. The young lose their white coloration by 14 –
17 weeks. They are carried by females
for up to 8 months, but are able to move on their own beginning at about 5
weeks. At two months young are playing
with each other and eating some leaves.
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 (Estes, p. 530)
Social Organization:
Territorial, with
a single dominant male. They are
primarily sedentary, with small, non-overlapping home ranges. Average troop size is 9 in Uganda, with a
range of 2 – 15. If a solitary monkey is
seen, it is most likely a sub-adult male that has recently been chased out of
its natal troop and is looking for a partner or a bachelor troop. (Estes, p.
524)
Dominant males
will occasionally allow other adult males if they act submissive, but it is not
uncommon for takeovers to be instigated by these males, sometimes followed by
infanticide of the first alpha’s offspring. (Estes, p. 525)
Although home
ranges are generally completely exclusive, one study of a troop in Kibale National
Park showed that there were several other troops
that would occasionally be within their boundaries. The study troop was seen to be completely
dominant over the other troops, though, and the researchers theorized that the
unusual traffic was due to the proximity of a swamp where several troops came
to feed. (Estes, p. 525)
Troop members
stay in very close proximity while feeding, usually the whole troop would be
contained within an 18-meter diameter circle.
Females and young stay closest together, with peripheral males keeping
the most distance. They participate in
an unusually high frequency of social grooming (up to 6% of daily
activity). The dominant male rarely
participates in this grooming. Grooming
peaks during the mid-day rest period, during the early morning, and when rival
troops are nearby. (Estes, p. 525)
One of the most
unusual behaviors of black-and-white colobus is the willingness of mothers to
allow other females to handle their very young offspring. They are rarely handled by their mothers or
other females after they reach 4 months of age. (Estes, p. 526)
The Matriarch
leads troop movements, except for challenges to rival troops, which are led by
the dominant male. (Estes, p. 526)
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, like we saw at Bagodi Wetlands.
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