Cross River Gorilla

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Lore & Background

The Cross River gorilla was formally described as a subspecies of the western gorilla, with the species Gorilla gorilla described by Thomas Savage in 1847. The population is recognised as two subspecies: the western lowland gorilla (Gorilla gorilla gorilla) and the Cross River gorilla (Gorilla gorilla diehli). Nearly all individuals of the western gorilla taxon belong to the western lowland gorilla subspecies, whose population is approximately 276,000 individuals. Just 250 to 300 of the only other western gorilla subspecies, the Cross River gorilla, are thought to remain. The nearest population of western lowland gorilla is some 250 km (160 mi) away. Both loss of habitat and intense hunting for bushmeat have contributed to the decline of this subspecies. In 2007, a conservation plan for the Cross River gorilla was published, outlining the most important actions necessary to preserve this subspecies. The government of Cameroon has created the Takamanda National Park on the border with Nigeria, as an attempt to protect these gorillas. The park now forms part of an important trans-boundary protected area with Nigeria's Cross River National Park, safeguarding an estimated 115 gorillas—a third of the Cross River gorilla population—along with other rare species. The hope is that these gorillas will be able to move between the Takamanda reserve in Cameroon over the border to Nigeria's Cross River National Park.

In Their Own Story

Estimates on the number of Cross River gorillas remaining is 250–300 in the wild, concentrated in approximately 9-11 locations. Recent genetic research and field surveys suggest that there is occasional migration of individual gorillas between locations. The nearest population of western lowland gorilla is some 250 km (160 mi) away. Both loss of habitat and intense hunting for bushmeat have contributed to the decline of this subspecies. In 2007, a conservation plan for the Cross River gorilla was published, outlining the most important actions necessary to preserve this subspecies. The government of Cameroon has created the Takamanda National Park on the border with Nigeria, as an attempt to protect these gorillas. The park now forms part of an important trans-boundary protected area with Nigeria's Cross River National Park, safeguarding an estimated 115 gorillas—a third of the Cross River gorilla population—along with other rare species. The hope is that these gorillas will be able to move between the Takamanda reserve in Cameroon over the border to Nigeria's Cross River National Park.

Reader's Guide

The Cross River gorilla is critically endangered. The World Conservation Union lists the western gorilla as critically endangered on its 2007 Red List of Threatened Species. The Ebola virus might be depleting western gorilla populations to a point where their recovery might become impossible, and the virus reduced populations in protected areas by 33% from 1992 to 2007, which may be equal to a decline of 45% for a period of just 20 years spanning 1992 to 2011. Poaching, commercial logging, and civil wars in the countries that compose the western gorillas' habitat are also threats. Furthermore, reproductive rates are very low, with a maximum intrinsic rate of increase of about 3% and the high levels of decline from hunting and disease-induced mortality have caused declines in population of more than 60% over the last 20 to 25 years. Rather, under the optimistic estimate scenarios, population recovery would require almost 75 years. Yet within the next thirty years, habitat loss and degradation from agriculture, timber extraction, mining and climate change will become increasingly larger threats. Thus, a population reduction of more than 80% over three generations (i.e., 66 years from 1980 to 2046) seems likely. In the 1980s, a census taken of the gorilla populations in equatorial Africa was thought to be 100,000. Researchers adjusted the figure in 2008 after years of poaching and deforestation had reduced the population by halve to approximately 50,000.

Did You Know?

• Just 250 to 300 Cross River gorillas are thought to remain in the wild.
• The Cross River gorilla differs from the western lowland gorilla in both skull and tooth dimensions.
• The nearest population of western lowland gorilla is some 250 km (160 mi) away from the Cross River gorilla.
• The government of Cameroon created Takamanda National Park on the border with Nigeria to protect these gorillas.
• An estimated 115 gorillas—a third of the Cross River gorilla population—are safeguarded in the trans-boundary protected area of Takamanda National Park and Nigeria's Cross River National Park.