Friday, 28 March 2014

The Angolan Black and White Colobus Monkey (Colobus angolensis ssp palliatus)

Since I spend most of my time following the Angolan Black & White Colobus monkeys of Diani I thought I would introduce them to you in more detail.

Angolan Black & White Colobus Monkey

Habitat & population:
I am following a sub species of the Angolan Black & White Colobus monkey (Colobus) Colobus angolensis ssp palliates (Family Cercopithecidae: Subfamily colobinae). Previously found along the entire coast activities like deforestation and hunting now mean they are only found in the south eastern part of Kenya and Tanzania coastal forests. There are estimated to be between 2 - 5,000 Colobus monkeys in Kenya and the latest census conducted by Colobus Conservation found there were approximately 450 individuals living in the Diani area. This is an increase on previous years and is also a good sign of the general health of the forest.

This species of Colobus monkey have black hair with a white brow band, cheeks and throat. They also have long haired white epaulettes streaming from their shoulders. The lower part of their tail is white and for males they have a white line from their buttocks to their penis where females just have a white patch by their buttocks. Colobus babies are born white and then turn grey and black, it is not till around three months old they get the adult colouration of black and white.

White baby
Showing the male white line

All Colobus species they are diurnal (active during the day), they have flattened nails, pads on their buttocks and their hind legs are longer than their fore limbs. They have a light-weight bone structure and elongated limbs as they spend their entire lives in the trees (arboreal), so this makes it easier for them to leap from tree to tree. They have four digits on their hands and do not have thumbs, however, on their feet they have five digits retaining their opposable big toe. The reduction of a thumb on their hands is thought to aid their movement through the forest. The name “Colobus” is thought to come from the Greek word “kolobus” meaning maimed or mutilated, due to their lack of a thumb.

A group of Colobus in the trees
Showing the feet of the Colobus and the opposable big toe.

The Colobus monkeys are specialist leaf eaters, occasionally taking in fruits and flowers and do not have cheek pouches. Their stomach is very large and has three separate chambers with specific bacteria that help to ferment and digest the leaves, very similar to the process of rumination in cows. They have been recorded to eat 46 different species, but only five species make up the greatest proportion of their diet. Due to the poor nutritional quality of their food they have to browse for many hours, consuming two to three kg of leaves per day (one third of their full body weight). This means they have to sleep for around a third of their day to aid the digestion. They even eat soil, clay, charcoal and rocks which is thought to assist in the digestion of toxic leaves.

Eating a tasty flower

Eating a bit of soft rock to aid the toxicity of certain leaves

Classic Colobus resting position during the day

Social Structure:
Groups are normally made up of one male and many females with between 3-25 individuals in well defined territories. The dominant male will protect the group from predators and rival groups whereas the dominant female will lead the group. Females remain in their natal troops for life while young males will leave their natal group to start bachelor groups, or to travel alone until they are able to take over their own group. Colobus reproduce all year round with a peak in September and it is thought the babies are born white to encourage other females of the group to take care of the infant; ‘aunting behaviour’. This will not only free up time for the mother to rest and feed, but allow the younger females a chance to practice mothering skills for when they have a baby.

A Colobus baby being passed to different females in the group

In Diani the Colobus are not a pest to tourists as they are not interested in human food and spend their time in the trees and not on the ground. For this reason they are well liked by visitors and the local people and see as a sign of health in the forest.

All photos appearing in this post are taken by me and the quality is low as my internet here is not that good.

Thank you for reading and I look forward to answering any questions you may have.

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