Classification and Range
The western lowland gorilla belongs to the family Pongidae, which includes four species of great apes: the gorilla, common chimpanzee, bonobo or pygmy chimpanzee and orangutan.
There are three recognized subspecies of gorilla, the western lowland gorilla (Gorilla gorilla gorilla), eastern lowland gorilla (Gorilla gorilla graueri) and the mountain gorilla (Gorilla gorilla beringei). The western lowland gorilla lives in six countries across west equatorial Africa; southeast Nigeria, Gabon, Cameroon, Central African Republic, Congo and Equatorial Guinea.
All gorillas live in primary and secondary tropical rain forests. Different subspecies range throughout various altitudes, from sea level to 12,500 feet (3,790 m).
Arm Span (fingertip to fingertip)
Adult male: Approximately 8 feet (2.4 m)
Adult female: Approximately 6.5 feet (2 m)
Adult male weight: 350-600 pounds (157-273 kg)
Adult female weight: 150-300 pounds (66-136 kg)
Estimated at 30-35 years in the wild. Average life span is 35-45 years in zoos, with the record being 54 years.
In the wild: Trees and herbaceous vegetation including leaves, shoots, stalks, stems, vines, bark, fruits and berries, and occasionally invertebrates such as termites.
At the zoo: Vegetables, fruits, leaf eater biscuits, browse (cut branches from a variety of trees, herbaceous plants, alfalfa, ferns, clover), non-fat milk and yogurt, and a vitamin and mineral supplement.
All subspecies of female gorillas sexually mature in the wild between the ages of 7 to 8 and in captivity approximately 5-1/2 years old. Males sexually mature in the wild between 8 to 9 1/2 years old and in captivity as early as 6-1/2. Males are not considered fully mature until about 15 years old. Gorillas do not have a distinct breeding season. Gestation lasts from 250 to 270 days. In the wild, female gorillas usually deliver their first offspring at 10 1/2 years old and at four year intervals thereafter. One infant is normally produced and twins are rare.
At birth, infants weigh 4-5 pounds (1.8-2.3 kg) and have sparse hair covering their pink-gray skin. At about nine to 10 weeks, they begin to crawl on their own and soon walk on all four limbs. A white patch of hair appears on the rump of gorilla infants at about the same time they begin to walk. The white patch helps the mother keep track of the infant and assists other group members in identifying the gorilla as an infant. The rump patch begins to disappear at about age 3, the same age that weaning usually begins. Females remain with their natal group until about age 8 or 9, then join an unrelated group or a solitary male. Males remain with their natal group until about age 12, then begin to go off on their own. Solitary males try to attract females from other groups to form their own group.
All in the Family
A family group includes one dominant silverback male, several adult females, adolescents, juveniles and infants. The group may also include one or two subordinate silverbacks. All adult males are silverbacks. Although gorillas are normally not aggressive, they can exhibit certain aggressive actions when disturbed. Adult males perform elaborate displays, including chest beating, running sideways and tearing up vegetation to frighten off an intruding male or other threat. Males also use these displays as a show of dominance within the group. Adult females can become aggressive when defending their infants, or while helping each other drive off rowdy, young adult males. The silverback is the peace keeper and stops occasional squabbles between females.
Vegetarians with Muscles
Gorillas are incredibly powerful, the largest great ape in the world. Regardless of their imposing appearance, they are in fact quite shy, gentle animals. Gorillas are virtually vegetarian and forage throughout the day in search of a variety of plants to consume. The hair of the western lowland gorilla is grayish-black and usually reddish on their head (particularly prominent in adult males). At about age 10, males begin to grow the distinctive silver-white saddle of hair on their back, which in western lowland gorillas continues to extend down the rump and thighs as the male gets older. Mountain gorillas have darker, longer hair.
Location at the Zoo
Woodland Park Zoo has two gorilla groups which can be viewed at the zoo's Tropical Rain Forest. Group 1 includes six members — a silverback male, two adult females, a subadult female, one juvenile female, and an infant female. Group 2 lives in a separate enclosure and also has six members — a silverback male, two adult females, two subadult females and one infant female.
All gorillas are endangered. The estimated population of wild western lowland gorillas is about 110,000 and the estimated population of eastern lowland gorillas is 10,500. Mountain gorillas are the most endangered and number about 650. The primary reason gorillas are endangered is because of habitat destruction caused by logging and agricultural expansion. The bushmeat trade, facilitated by logging, has become an immediate threat to the western lowland gorilla population, particularly in Cameroon. Additionally, infection from the Ebola virus has recently become a great threat, killing many gorillas.
Woodland Park Zoo participates in the Association of Zoos & Aquariums' (AZA) Species Survival Plan (SSP) for gorillas. We have helped diversify the captive gene pool with our breeding efforts. The zoo also works to educate the public about gorillas and this is the first step to gorilla conservation.
How You Can Help!
The effort to save endangered species requires cooperation and support at the international, national, regional and individual levels. You can help in this cause. Join and become active in a conservation organization of your choice. Don't buy products made from wild animal parts. Let your elected representatives know your views about protecting endangered species and wild habitats.
Visit our How You Can Help page to find out ways you can support conservation programs at the zoo.
Sources and Suggested Reading
Dixon, A. F. 1981. The Natural History of the Gorilla. New York Columbia University Press, New York, NY. 202 p.
Fossey, Dian. 1983. Gorillas In The Mist. Houghton Mifflin Company, Boston, MA. 326 p.
Morris Animal Foundation Mountain Gorilla Studies
Peterson, Dale. 2003. Eating Apes. University of California Press, Berkeley, CA. 320 p.
Redmond, Ian. 1995. Gorilla. Alfred A Knopf Inc., New York, NY. 63 p.
Zoobooks. 1994. Apes. Wildlife Education Ltd., San Diego, CA. 18 p.
Meet our Gorillas
Born: Wild-born in 1968. Father of Jumoke and Alafia. Grandfather of Nadiri, Naku and Akenji.
Weight: 410 pounds (186 kg)
History: A member of the original Woodland Park Zoo group, Pete is the group leader. As an older male with much parenting and leadership experience, he provides a lot of stability for the group.
Characteristics: Red hair on head and silver back, asymmetrical facial features, deep-set eyes, "frowning" expression
Born: Wild-born in 1968. Mother of Alafia, grandmother of Naku and surrogate mother to Akenji.
Weight: 237 pounds (107.5 kg)
History: Member of the original Woodland Park Zoo group, Nina is the matriarch of this group and a very good mother, grandmother and great grandmother with four surviving offspring (three at other zoos). Nina is a great adoptive mother to Akenji and they have a very close bond. Due to a kidney problem, Nina is on birth control pills to prevent her from becoming pregnant.
Distinguishing features: Short, stocky stature, wrinkled face, large, round stomach. While resting, she sometimes has her mouth open, revealing a pink inner mouth and tongue. Nina is very interested in people.
Born: January 26, 1979. Father of Ngozi, Naku, Akenji and Calaya.
Weight: 395 (179.2 kg)
History: Vip was the first captive-born gorilla in the Netherlands, eventually moving to the Franklin Park Zoo in Boston. In 1996 he moved here and became the leader of this group. Because he has no breeding relative in North America, his offspring are especially valuable to the captive gorilla population. Vip is an excellent father and takes great interest in his offspring. He has sired five daughters while at Woodland Park Zoo.
Characteristics: Very low brow ridge (which makes him look agitated), extremely large head, very black hair with a striking silvery back. The toes on both feet are often curled.
Born: May 9, 1985 at Woodland Park Zoo. Daughter of Pete. Mother of Nadiri and Akenji.
Weight: 255 (116 kg)
History: Reared in Group 1, Jumoke was moved out to avoid inbreeding. She was unable to rear her first offspring, Nadiri. She then proved to be a good mother to her second offspring (who now lives at another zoo), but surprised zoo staff by refusing to rear her third offspring, Akenji.
Distinguishing features: Black back, taller than Amanda, has a higher, more pointed crest. Jumoke is a good tool user and is very confident around Vip.
Born: Wild-born in 1970. Mother of Ngozi and Calaya.
Weight: 218 pounds (98.9 kg)
History: Raised at the Toronto Zoo, Amanda moved to Woodland Park Zoo in 1994. She gave birth to her first offspring in 1995, but the male infant died five days later. She then gave birth to Ngozi in March 1998 and Calaya in August 2002. She is an excellent mother.
Characteristics: Prominent silver back, small but muscular stature (especially in upper body), small, smooth face with longer hair on her arms than Jumoke.
Born: August 30, 2002 at Woodland Park Zoo. Daughter of Vip and Amanda
Weight: 160 pounds (72.6 kg)
History: Calaya is the second surviving offspring of Amanda and Vip. As the youngest member of the group, she is tolerated by all other members.
Distinguishing features: Calaya is independent and a great climber.
Born: October 20, 2007 at Woodland Park Zoo. Daughter of Vip and Amanda
Weight: 81 pounds (36.7 kg)
History: This is the third surviving offspring of Amanda and Vip. As the youngest member of the group, she is tolerated by all other members. Distinguishing features: Mostly held in the arms of mother Amanda. As she grows, she will become more independent.
Born: February 20, 1978
Weight: 360 pounds (163 kg)
History: Leonel (Leo) was captive-born in Brownsville, Texas, and has been at several zoos. He came to WPZ from Zoo Grandby in Canada. In December 2008, he moved here and is now the silverback of Group 3, which also includes Nadiri Akenji. We hope he will sire offspring with both female.
Distinguishing features: A slightly small frame for an adult silverback gorilla. Often seen chewing a Kong-brand toy.
Born: February 12, 1996. Daughter of Congo and Jumoke. Half sister to Akenji.
Weight: 221 pounds (100 kg)
History: Jumoke (in gorilla group 2) was unable to raise Nadiri due to a traumatic delivery. Nadiri was hand-raised by zoo staff and gradually introduced at 5-1/2 months old to this group, her adoptive family. Nadiri is gentle and playful with Akenji and Naku. She is very important genetically to the captive population of gorillas because she is the only living offspring of her father, Congo, who died two weeks after Nadiri's birth.
Characteristics: Nadiri often plays with zoo visitors through the viewing glass. She is more slender than Nina. Also still spends time with Group 1.
Born: July 24, 2001 at Woodland Park Zoo. Daughter of Vip and Jumoke. Adoptive mother is Nina.
Weight: 180 pounds (81.7 kg)
History: Jumoke was unwilling to raise Akenji, so she was partially hand-raised by zoo staff. She was slowly introduced to this group and has a close bond with Nina, her adoptive mother.
Characteristics: She is the smallest member of the group. She has a small face and smooth hair, and is stockier than Naku. Very independent and confident, Akenji still spends some time with Group 1.