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The western lowland gorilla is the largest of the living primates. Males can be up to 6 feet tall and 400 pounds while females range to 5 feet and 200 pounds. They have black to brown-gray coats that turn gray with age.
Adult males have a broad, silvery-white "saddle" on the back, extending to rump and thighs. The species has small ears and nostrils bordered by broad ridges that extend to the upper lip. Young have a white tuft of hair on the rump.
Cameroon, Central African Republic, Gabon, Congo and Equatorial Guinea
The gorilla is listed as critically endangered, and commercial trade of this species is prohibited by international law. The principal causes of population decline are habitat destruction and hunting.
Poachers prize adult males and disrupt troops by killing leaders. Lincoln Park Zoo participates in the Gorilla Species Survival Plan® and is world famous for its success in breeding western lowland gorillas.
Tropical secondary forest: the herbs, shrubs and vines that make up its diet grow best where the open canopy allows plenty of light to reach the forest floor.
Western lowland gorillas are herbivorous, feeding mainly on leaves and stems, althoug they never strips one site completely. The western subspecies takes a higher proportion of fruit—a more limited resource—which appears to limit troop size to 5–10 individuals.
Troops consist of a dominant silverback plus a harem of females with their young, including subadult males. Lone males occur, and troop ranges can overlap.
The species is diurnal (active during the day) and mainly terrestrial. Gorillas walk on the soles of rear feet and the knuckles of forelimbs. They will build nests on the ground or in trees (especially young gorillas).
Mating is non-seasonal, with a single young born after a 9-month gestation period. Infants weigh 4–5 pounds. They cling to dam within a few days of birth, crawl at about nine weeks, walk at about five months and are weaned at 2–3 years. Females mature at 7–8 years, males later. Females leave these troop to join other troops or lone males; adult males leave without conflict.
From Sichuan takin pregnancies to black-footed ferret semen cryopreservation, western lowland gorilla stress hormones to pygmy hippo skin swabs, there’s no such thing as a typical day at the office for Rachel Santymire, Ph.D., director of Lincoln Park Zoo’s Davee Center for Endocrinology and Epidemiology.