With a population numbering fewer than 300 individuals, Cross River gorillas (Gorilla gorilla diehli) are the rarest and most endangered of the world's four gorilla subspecies. Although they remain threatened by habitat loss and illegal bushmeat hunting, new research shows the gorillas have a bit more potential habitat to roam, and in fact inhabit a slightly greater range than previously known.

Cross River gorillas only live in the mountainous forests along the border separating Nigeria and Cameroon. Scientists from the North Carolina Zoo, the Wildlife Conservation Society (WCS) and other groups combined satellite imagery with ground surveys of the area to find that the gorillas occupy 50 percent more range than previously documented. They also found even more area that could make suitable gorilla habitat in the future. The research was published in the online edition of the journal Oryx.

"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," lead author Richard Bergl of the North Carolina Zoo said in a prepared statement.

Co-author Andrew Dunn of the WCS said this research shows Cross River gorillas can further expand their range into these potential new habitats, "provided that steps are taken to minimize threats to the population."

The most pressing of those threats is the current isolation of many Cross River gorilla subpopulations. For example, the researchers point to the gorillas living in Afi Mountain Wildlife Sanctuary in Nigeria, which must cross farmland if they wish to connect with other groups.

The authors say maintaining connective corridors—a goal for which this research is the first step—is an important element in the long-term survival of the Cross River gorilla. They will present their findings at an upcoming workshop in Cameroon to help inform future species- and habitat-management decisions. "A new action plan for the subspecies will build on the collaborative partnership already underway between Nigeria and Cameroon and ensure a future for this unique primate," said James Deutsch, executive director of WCS's Africa Program.

Previously in Extinction Countdown: "Gorillas in the list: New extinction fears for central African gorillas"

Photo by Nicky Lankester. Courtesy of Wildlife Conservation Society