News Release

In Uganda's Impenetrable Forest, A New Census For Mountain Gorillas

Peer-Reviewed Publication

Wildlife Conservation Society

A team of scientists has counted nearly 300 mountain gorillas living in Uganda's Bwindi Impenetrable Forest National Park, bringing the total to around 600 for this most endangered gorilla sub-species.

The census, conducted in October and November by the Bronx Zoo-based Wildlife Conservation Society, International Gorilla Conservation Programme, the Institute of Tropical Forest Conservation and the Uganda Wildlife Authority resulted in a tally of 292 individual gorillas from 28 groups, along with seven lone silverbacks (adult males).

Using survey techniques developed in the Virunga Conservation Area, where the other, much better-known population of mountain gorillas live, researchers followed trails and counted nests. To lessen the possibility of missing groups or counting them twice, more survey teams were used than in the past, counting over a shorter period of time.

Each night, gorillas build a new nest, and researchers can tell the age of the animal that slept there by the size of dung piles left behind, and if it is a female by the presence of infant dung. In addition, silvery hairs found in the nest can reveal the presence of adult males. Researchers collected hairs from every nest for DNA fingerprinting, to confirm that no groups were counted twice, and to understand the genetic differences between the Bwindi and Virunga populations. Bwindi gorillas differ from Virunga gorillas by their shorter hair and slightly longer limbs. Further research will be needed to confirm whether the Bwindi gorillas are themselves a sub-species distinct from the Virunga population.

The steep mountains and thick, thorny brush that give the Impenetrable Forest its name provided a significant challenge for the census teams that scoured all areas of the park in search of gorilla trails. Teams consisted of national park staff from Uganda, Rwanda, and Congo as well as visiting scientists from conservation organizations working in the region, marking another positive milestone to protect gorillas.

The future of these rare gorillas remains uncertain, however. "Given that the Virunga Volcanos is currently a war zone and that park staff cannot even enter this region to monitor the gorillas, there is strong concern in the conservation community that there may be even fewer than 600 animals," said Dr. Andrew Plumptre, assistant director for Africa programs of the Wildlife Conservation Society..

The results of the Bwindi census will be critical to a strategic analysis to be conducted at the upcoming Mountain Gorilla Population and Habitat Viability Analysis (PHVA) Workshop, organized by the Uganda Wildlife Authority and the Conservation and Breeding Specialist Group of IUCN. The workshop will be held in Uganda from Dec. 8-12, and will bring together, for the first time, representatives from national parks of the three mountain gorilla range countries and conservation agencies working on gorillas.

The workshop participants will work together to design a regional plan of action that will best ensure the conservation of these endangered gorilla populations. "Team members from the recent census will attend the PHVA workshop and it is hoped that these census results, in conjunction with the exciting spirit of collaboration between the organizations and field personnel involved in the census, will inspire the further cooperation necessary to ensure the conservation of these rare gorilla populations," said Dr. Liz Macfie, programme manager for the International Gorilla Conservation Programme in Uganda.

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