The eastern lowland gorilla (Gorilla beringei graueri) or Grauer's gorilla is a Critically Endangered subspecies of eastern gorilla endemic to the mountainous forests of eastern Democratic Republic of the Congo. Important populations of this gorilla live in the Kahuzi-Biega and Maiko National Parks and their adjacent forests, the Tayna Gorilla Reserve, the Usala forest and on the Itombwe Massif.
It is the largest of the four gorilla subspecies. It has a jet black coat like the mountain gorilla (Gorilla beringei beringei), although the hair is shorter on the head and body. The male's coat, like that of other gorillas, greys as the animal matures, resulting in the designation "silverback".
There are far fewer eastern lowland gorillas compared to western lowland gorillas. According to a 2004 report there were only about 5,000 eastern lowland gorillas in the wild, down to fewer than 3,800 in 2016, compared to over 100,000 western lowland gorillas. However, a survey in 2021 gave an estimate of up to 6,800 suggesting the decline was not as bad as feared although they are still facing severe threats. Outside their native range, only one female eastern lowland gorilla lives in captivity, at the Antwerp Zoo in Belgium.
Physical description
thumb|Skeleton and stuffed of Eastern lowland gorilla at [[Musée d'Histoire Naturelle de Lille|MHNLille]]
Eastern lowland gorillas are the largest subspecies of gorilla and the largest living primates. An older weight calculated based on eight wild adult males is .
Habitat and ecology
Gorillas spend long hours feeding on plant matter every day. Gorillas are stable apes as they stay together for months and years at a time, much like the structure of a family. Groups of eastern lowland gorillas are usually larger than those of western gorillas. It is commonly believed that the structure of the gorilla group is to prevent predation.
Reproduction
thumb|Infant in [[Kahuzi-Biéga National Park]]
A female will give birth to a single infant after a gestation period of about months. They breastfeed for about three years. The baby can crawl at around nine weeks old and can walk at about 35 weeks old. Infant gorillas normally stay with their mother for three to four years and mature at around 8 years old (females) and 12 years old (males).
Threats
thumb|upright|Male eastern lowland gorilla
Threats to the eastern lowland gorilla's survival include poaching, civil unrest, and the destruction of gorilla habitat through logging, mining, and agriculture. It is eaten by displaced peoples residing in the region affected by the civil war, militia groups and loggers and miners. Surveys have shown that great apes, chimpanzees and bonobos comprise 0.5–2% of the meat found in bushmeat markets. Researchers have also stated that it is more difficult to patrol areas outside of the park and expect to find even higher levels of poaching. Reports from 2007 state that of cassiterite (US$45 million), of wolframite (worth US$4.27 million) and of coltan (US$5.42 million) were exported in 2007. A recent genome study, which included all four subspecies of gorilla, aimed to identify the levels of diversity and divergence among the remaining populations of gorilla. Results showed that the eastern lowland gorilla subspecies was in fact two distinct subgroups.