Mahale Mountains, the home of the primates

By Paul Siololo - Guide, Greystoke Mahale

Mahale Mountain National Park is a tourist attraction due to high populations of different species of primates. Some of these primate species are only found in this park and Gombe stream National Park, both are on the eastern shores of Lake Tanganyika.

The higher primate densities here in Mahale are probably due to suitable geographical location that has created good habitat and sufficient fruits or food to these primates. There are about eight species of primates found in Mahale. The most popular one is the chimpanzees. Others include Yellow baboon, Vervet monkeys, Red colobus and black and white colobus, Red tailed monkey, silver back monkey and two nocturnal species, the great and lesser bush-babies. Most of these species are found in the dense forests in the Mahale Mountains to the side toward Lake Tanganyika. The western sides of the Mahale Mountains experience a lot of rainfall annually, because of humid air that flows from Lake Tanganyika toward the Mahale mountains. As a result there is a higher diversity of vegetation, which supports an amazing great diversity of primate species.

So, when one plans a trip to Mahale— think and look to enjoy impeccable behavioral aspects of the other Mahale’s primates. Of course, with chimpanzees being the top in the list.  

Increase in yellow baboon population and the effects of territorial expansion by the Mahale chimps

By Kakae Saiteu, Guide - Greystoke Mahale.

When first the M-community chimpanzees were habituated and even for the subsequent three decades of their habituation, the chimpanzees did not go beyond or as high as 1500 meters from the sea level. They stayed in the lower part of the Kasoje forest and consumed fruits of several plants species.

It is in the 1990s when for the first time chimpanzees were noticed going up in the high altitude for considerable numbers of days. It is then; the Japanese proposed the development of new trekking trails for instance route 7 to follow the chimpanzees. Otherwise the research without route 7 (skyway) was completely impossible.

When exploring why the Chimpanzees are moving to higher ground a number of factors were disclosed. To the scope of this blog only one is described, which is the increase in number of yellow baboon from two troops in 1970s to five in 1990s within the territory of the habituated chimpanzees. An increased yellow baboon population led to more competition between them and chimpanzees, a factor that render yellow baboon to learn to eat fruits which they have never eaten before, like Saba Florida, Pseudopondia microcarpa etc. Also unlike chimpanzees, yellow baboons eat fruit before they are ripe. Therefore Granite garcinia, Cordia milleni, Mango and Harungana madagascariensis fruits, which chimpanzees love eating weren’t available to the same degree as before. In that case, chimpanzees found they can’t compete equally with yellow baboon. 

To alleviate that interspecies competition, chimpanzees have expanded their territory to higher altitude where yellow baboon can’t explore as they prefer to hang about in the edge of forest and also to have more foraging areas to meet their daily needs.