In 1993 when rebels fighting in the Rwandan civil war moved higher into the mountains, the endangered mountain gorillas made famous by researcher Dian Fossey nearly disappeared. But their sudden departure wasn’t due to increased poaching or the bullets of war but rather they had moved higher up into the mountain range where the fighting could not reach them. It took satellite images to locate them through the dense cloud cover. Researchers and conservationists who were forced to flee the area because of the war heaved a sigh of relief.
Now satellite imagery is proving helpful again. This time with the world’s rarest gorilla, the Cross River gorilla. With a population of fewer than 300 individuals, they are listed as critically endangered.
Researchers analyzed high-resolution satellite images from the Cross River region, the mountainous area between Nigeria and Cameroon. They mapped forests and other types of so-called "land-cover." Field researchers on the ground traveled miles to 400 specific control points to confirm the accuracy of the images. Then the entire region was split into 30 by 30 meter areas, and each was rated for suitable habitat. Steep forested areas with little human activity were rated high, while low areas with high human activity were rated low.
Researchers then used these suitability maps and performed field surveys in 12 of the highly-rated locations. These areas had no previous record of gorillas but surprisingly when the field researchers went in they found signs of gorilla life—dung and nests—in 10 of the 12 locations. Their research is published today in the journal Oryx.
Richard Bergl, lead author of the study and curator of conservation and research at the North Carolina Zoo, was quoted in a press release:
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. The study is a great example of how scientific research can be directly applied to great ape conservation.
The findings from this study show that the area occupied by gorillas is more than 50 percent larger than was previously known. The satellite images also helped map out populations that are more isolated because of a lack of any connective corridors. Isolated populations are at higher risk of dying out. High human population density and intense natural resource exploitation contribute to the degradation of connective corridors that connect groups of gorillas.
According to the Wildlife Conservation Society the maintenance of such corridors is crucial for the gorillas survival and this study provides a step toward creating ways to rehabilitate these areas.