page_title: Cross River gorilla
section_title: Behavior
hierarchical_section_title: Cross River gorilla / Behavior
caption_attribution_description: English: Cross River Gorilla (Gorilla gorilla diehli) Native to the cross river area on the border of Cammeroon/Nigeria, the Cross River Gorilla is considered to be one of the most endangered primates and one of the rarest. Approximately only 300 left in the wild, and just one in captivity at the Limbe Wildlife Centre, Limbe, Cameroon. This lady gorilla is called Nyango. Please credit Julie Langford (photographer) when using this work, and also raise attention to the work of Limbe wildlife Centre by providing a link to their website. http://www.limbewildlife.org
context_page_description: The Cross River gorilla is a subspecies of the western gorilla. It was named a new species in 1904 by Paul Matschie, a mammalian taxonomist working at the Humboldt University Zoological Museum in Berlin, but its populations were not systematically surveyed until 1987.
  It is the most western and northern form of gorilla, and is restricted to the forested hills and mountains of the Cameroon-Nigeria border region at the headwaters of the Cross River. It is separated by about 300 km from the nearest population of western lowland gorillas, and by around 250 km from the gorilla population in the Ebo Forest of Cameroon. Estimates from 2014 suggest that fewer than 250 mature Cross River gorillas remain, making them the world's rarest great ape. Groups of these gorillas concentrate their activities in 11 localities across a 12,000 km² range, though recent field surveys confirmed the presence of gorillas outside of their known localities suggesting a wider distribution within this range. This distribution is supported by genetic research, which has found evidence that many Cross River gorilla localities continue to maintain contact through the occasional dispersal of individuals.
context_section_description: A study published in 2007 in the American Journal of Primatology announced the discovery of the subspecies fighting back against possible threats from humans. They "found several instances of gorillas throwing sticks and clumps of grass". This is unusual. When encountered by humans, gorillas usually flee and rarely charge.
  Cross River gorillas have certain nesting behaviors (i.e. mean nest group size, style of the nest, location of the nest, and nest reuse patterns) that depend on things such as their current habitat, climate, food source availability and risk of attack or vulnerability. According to research done on the Cross River gorillas living in the Kagwene Gorilla Sanctuary, there is a high correlation between whether a nest is constructed on the ground or in a tree and the season. From April up until November, Cross River gorillas are more likely to build their nests within a tree, and from November on they are more likely to build it on the ground. Overall, it was found that more nests built at night were built on the ground as opposed to in trees. This species is also more likely to construct nests during the wet season than the dry season, as well as construct more arboreal nests in the wet season. It was found that day nest construction was more common, especially in the wet season. Reuse of nesting sites was also found to be common, although it did not have any relation to the season. And, their mean nest group size is from four to seven individuals. Although, nest group size varies depending on the location of the species.
  The groups of Cross River gorillas consist mainly of one male and six to seven females plus their offspring. Gorillas in lowlands are seen to have less offspring than those in the highlands. This is thought to be because of the hunting rate in the lowlands and infant mortality rate. The groups in the highlands are densely populated compared to those in the lowlands.
  The Cross River gorilla's diet consists largely of fruit, herbaceous vegetation, liana, and tree bark. Much like their nesting habits, what they eat is contingent on the season. Observations of the gorilla indicate that it seems to prefer fruit, but will settle for other sources of nutrition during the dry season of about 4–5 months in northern regions. Cross River gorillas eat more liana and tree bark throughout the year, and less fruit during dry periods of scarcity.
caption: Nyango, the only known Cross River gorilla in captivity. She died on October 10, 2016.[18]
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