Gorilla Journal 10, June 1995

Gorillas Found in Zaire

The Lost Gorillas Expedition found a small population of eastern lowland or Grauer's gorillas at Mt. Tshiaberimu in Zaire. Mt. Tshiaberimu (1,850 to about 3,100 m high) is located off the northwest corner of Lake Edward in eastern Zaire. This roughly 60 km² of mountain forest is all that remains of what were more than 450 km² of forest earlier this century. Mt. Tshiaberimu, which once held a large population of gorillas, is part of the Parc National des Virunga but the corridor connecting it to the main portion of the park has been encroached upon and destroyed. Conrad Aveling undertook a survey of Mt. Tshiaberimu in 1986 and concluded that no more than 20 gorillas remained.
From 30 May through 7 June 1995 we undertook a census of the gorillas there, examined their habitat, and assessed the threats to the area. This work was undertaken with considerable cooperation and assistance from the park wardens and rangers, and other personnel of the IZCN (Institut Zairois pour la Conservation de la Nature). Funding was provided by the Berggorilla & Regenwald Direkthilfe and Zoo Atlanta.
Three teams of guides and researchers searched suitable habitat for gorillas for seven consecutive days. Groups of 4 and 11 gorillas, plus one lone adult male, were located during this intensive search. We believe that the total number of gorillas remaining on Mt. Tshiaberimu is 16-18 and that only two groups occur. They use an area of approximately 18 km² at 2,800-2,900 m in the southwest corner of Mt. Tshiaberimu. This is an area dominated by high bamboo (Arundinaria alpina) and large Podocarpus latifolius, intermixed in some places with Galiniera saxifraga, Ilex mitis, Rapanea melanophloeos, Xymalos monospora, Mimulopsis spp. and Sericostachys scandens.
For as far as one can see from the high points on Mt. Tshiaberimu, there is no natural forest remaining in the region except for a few square kilometres of forest on some of the higher, distant ridges. Even these are, however, being felled and will probably be completely destroyed within the next few years. There is extensive agricultural encroachment around the entire boundary of Mt. Tshiaberimu and this is, undoubtedly, the greatest single threat to the area and its gorillas. In some places, the forest has been completely removed for a distance of more than 1 km inside the boundary. Pit-sawing is another serious problem. We estimate that more than 500 large Podocarpus have been pit-sawn during the last few years. There is ample evidence that gold mining along the rivers was at a high level in the recent past as there is much damage to the river bed, river banks and bordering forest. This activity appears to have declined considerably in recent years.
Poaching is at a very low level at this time but was probably much more prevalent in the past. Only one active trap was found although several old traps set for blue monkey (Cercopithecus mitis stuhlmanni) and L'Hoest's monkey (Cercopithecus lhoesti) were located. Black-fronted duiker (Cephalophus nigrifrons) and yellow-backed duiker (Cephalophus sylvicultor) are still present but at extremely low densities. It may be that poaching is not a worthwhile activity given the low densities of prey. There was no evidence that gorillas are hunted on Mt. Tshiaberimu and the park angers with whom we worked claimed to have never heard of gorilla hunting in the area.
Signs of elephant were abundant throughout the area between 2,600 and 3,100 m. The rangers estimate that about 30 elephants remain on Mt. Tshiaberimu. There is almost certainly no movement of elephants between this area and other parts of the park as the former corridor is densely populated by people.
During the survey, one of us (TMB) collected data on the avifauna between 2,550 m and 3,100 m. 15 of the 33 Albertine Rift Afromontane Region endemic bird species and subspecies were observed. Only a few of the regional endemics not seen would be expected to occur above 2,500 m. Two species not previously known to be present in the highlands to the west of Lake Edward were found, the Kivu ground thrush (Zoothera tanganjicae) and Shelley's crimson-wing (Cryptospiza shelleyi). It is likely that a few other regional endemics occur but were over- looked during this short survey. Mt. Tshiaberimu has a rich avifauna with several species of particular conservation concern.
It is clear that the forests of Mt. Tshiaberimu, and the important biodiversity they support, are under severe threat from the surrounding human population. Conservation inputs from outside of Zaire to IZCN are urgently needed if this area is to have any long-term future. We recommend that (1) immediate material and logistic support be provided to the twelve park rangers working to protect Mt. Tshiaberimu and (2) that a multi-faceted, long-term conservation project for this area be initiated no later than 1996.

Thomas M. Butynski and Esteban Sarmiento

Dr. Thomas M. Butynski has conducted wildlife research in Africa since 1971. From 1978 to 1993 he studied primates and worked on rain forest conservation in Uganda. Now he works for Conservation International and in addition for the IUCN/SSC Primate Specialist Group. Since 1995 he has made surveys in endangered montane forests in eastern Zaire/Democratic Republic of the Congo.
Dr. Esteban Sarmiento is a functional anatomist in the American Museum of Natural History. His primary research interest involves the skeletons of hominoids. He has taught in the USA, South Africa and Uganda.

Mt. Tshiaberimu overview

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