New hope for world’s rarest gorilla

FINDING ROOM TO GROW: The Cross River gorilla. Picture: Nicky Lankester

'There's still plenty of space for the population to expand'

February 2012: The world's rarest gorillas have more suitable habitat than previously thought, according to the latest study.

Encouragingly, the area includes vital corridors that, if protected, can help Cross River gorillas move between sites in search of mates.

The Wildlife Conservation Society and the North Carolina Zoo analysis, which used a combination of satellite imagery and on-the-ground survey work, will help guide future management decisions for the gorillas living in the mountainous border region between Nigeria and Cameroon.

Area occupied with gorillas 50 per cent larger than thought
‘We're pleased with our results, which have helped us to identify both new locations where the gorillas live and apparently unoccupied areas of potential gorilla habitat,' said Dr Bergl of the North Carolina Zoo, lead author of the study.

WCS conservationist and co-author Andrew Dunn said: ‘The good news for cross river gorillas is that they still have plenty of habitat in which to expand, provided that steps are taken to minimize threats to the population.'

Overall, the findings of the study represent a significant expansion of known Cross River gorilla range. The area now known to be occupied by gorillas is more than 50 per cent larger than had previously been documented. The findings also support recent genetic analyses that suggest a high degree of connectivity between the 11 known locations where gorillas occur.

'Connective corridors are vital for long-term survival'
The study also located parts of the population under threat from isolation through fragmentation. For example, Afi Mountain Wildlife Sanctuary in Nigeria, which contains a significant portion of the Cross River gorilla population, is only tenuously connected to the nearest sub-population of gorillas by farmland and other forms of degraded habitat.

‘For small populations such as this one, the maintenance of connective corridors is crucial for their long term survival,' said WCS researcher Inaoyom Imong. ‘The analysis is the first step in devising ways to rehabilitate degraded pathways.'

Rarest gorilla subspecies
The Cross River gorilla is the rarest of the four subspecies of gorilla, numbering fewer than 300 individuals across its entire range, limited to the forested mountainous terrain on the border region of Nigerian and Cameroon. The subspecies is listed as Critically Endangered and is threatened by both habitat disturbance and hunting, as the entire population lives in a region of high human population density and heavy natural resource exploitation.