The Western Lowland Gorilla can be up to 6 feet tall when standing and can weigh up to 450 pounds. It has a broad chest, a thick neck of muscle, as well as very strong hands and feet. Short, fine, gray-black or brown-black hair covers the entire body except the face. A prominent ridge of bone juts out above its eye, and flared nostrils. In comparison to the mountain gorilla, the Western Lowland has a wider and larger skull. Also, the big toe of the Western Lowland Gorilla is spread far apart from the alignment of his other four toes.
The most abundant species of gorilla is the Western Lowland Gorilla. Populations are estimated at about 40,000. Eastern Lowland Gorillas, found only in Zaire, number from 3,000 to 5,000. They are located in small pockets of tropical rainforest areas in the eastern part of the Congo. The Western Lowland Gorilla, however, is found in tropical rainforests in eastern Nigeria, Cameroon, southwestern Central African Republic, Equatorial Guinea, the Congo, Gabon, and Cabina.
The gorilla lives in groups called troops and spends most of its time on the ground. Although, juveniles may by seen playing in trees. Each troop, from 7-20 gorillas, is led by a "silverback" male who protects and keeps the group together. Rarely violent or aggressive, gorillas are typically quiet and gentle. However, they have been known to charge toward an antagonisitic troop member, if only to intimidate them. They rarely make actual contact with one another under these intense circumstances. Though now a behavioral stereotype, males will in fact beat their chests as part of a ritual that sometimes includes hooting and thumping on the ground. This act is not clearly understood, though it appears to reflect excitement and not serve as merely a show of strength. Actually, dominance is reinforced through grooming displays within the troop.
The Western Lowland Gorilla has a gestation period of 8-9 months. Birth occurs with the female in a supine position, over the course of a few minutes. After the baby is delivered, the mother severs the umbilical cord. The offspring are born helpless and must be carried in the mother's arms. A new born weighs 3-5 pounds. Growing at twice the rate of a human baby, they are able to crawl and ride their mother's back at 3 months old. They continue to ride their mother's back until they are 3.5 - 4 years old. Female gorillas become sexually mature between 6-9 years of age. The estrus cycle lasts 26-30 days. A successful female gorilla will have between 3-6 offspring in a lifetime. Male gorillas sexually mature later in life, between 9-12 years old. There is no set time of the year to give birth; offspring are born year round. A normal, healthy, gorilla may live up to 37 years.
The Western Lowland Gorilla has no known enemy -- except humans. Mankind has threatened their livelihood for over a century, and has caused them to become endangered through the degradation of the tropical rainforest. Illegal hunting for meat, big game hunting, the subsequent sale of live young, and over-collection by zoos and research institutions are all contributing factors to the endangerment of the Western Lowland Gorilla. Many have been shot and killed in the name of self-defense -- because if provoked enough, gorillas will charge toward an antagonist and try to frighten them away. Their last chance for survival may be a few gorilla sanctuaries in Africa, world-wide zoos, and other captive environments that offer security and a comfortable habitat.
Note: Some information has been excerpted from World Wildlife Fund, and the sites: "www.lazoo.org/learnfiles/ZooDiscoveryKit/Gorillafacts.html" , and "animaldiversity.ummz.umich.edu/accounts/gorilla"