The new census tallied more than 125,000 western gorillas in two adjacent areas in the northern part of the country, covering an area of 18,000 square miles (47,000 square kilometers). Previous estimates from the 1980s placed the entire population of western lowland gorillas, which occur in seven Central African nations, at fewer than 100,000. Since then, however, scientists had believed that this number had dwindled by at least half, due to hunting and disease.
The census data were released at a press conference at the International Primatological Society Congress in Edinburgh, Scotland. The WCS scientists who worked on the census include Fiona Maisels, Richard Malonga, Hugo Rainey, Emma Stokes, and Samantha Strindberg.
The new census was the result of intensive fieldwork carried out by the Bronx Zoo-based WCS and the Government of Republic of Congo. The researchers combed rainforests and isolated swamps to count gorilla "nests" to accurately estimate the population. Gorillas construct nests each night from leaves and branches for sleeping. Population densities ranged as high as eight individuals per square kilometer in one particularly rich forest patch, which ranks as among the highest gorilla density ever recorded.
http://www.wcs.org/gorilladiscovery/press-release
