Wells, a senior lecturer in the School of Psychology at Queen's University Belfast, Ireland, explained to Discovery News that she studied six western lowland gorillas housed together at Belfast Zoological Gardens in Northern Ireland. The gorilla group includes both wild-born and captive-born males and females of different ages.
The gorillas were observed for four hours a day on 20 busy days, when the average number of visitors was around 1,288. The gorillas also were observed on 20 quiet days, usually on weekdays when an average of six people visited the zoo.
During these periods, Wells documented known gorilla behaviors, such as standing, sitting, resting, grooming, aggression, playing, walking, running, climbing, socializing and banging on the viewing window. She also recorded "abnormal" behavior, like repetitive teeth clenching, body rocking and spinning.
Visitors seemed to have no effect on basic behaviors, such as standing, walking and socializing.
When few visitors were present, however, the gorillas tended to relax and rest more. When the zoo was crowded, the gorillas often banged on the viewing window, exhibited all of the abnormal behaviors, repeatedly groomed themselves and fought more often.
Wells said visitors could affect all primates, not just gorillas. Since it is hard to know when zoos will be busy or not, she said factors other than visitor group size could lessen the possible human impact.
"Primates are more likely to be excited by zoo visitors if they appear in large numbers, display erratic behaviors, elicit high levels of noise or deviate greatly from the norm in terms of their physical appearance, for example height, clothing," said Wells, adding that some zoos even play classical music, which seems to soothe the animals and drown out visitor noise.
Mark Challis, acting zoo manager at Belfast Zoological Gardens, said he agreed with Wells that humans might affect some animals.
However, he added, "Not all animals are bothered by crowds or noise. Some species and individuals (appear to be) ambivalent, (while) some appear to enjoy the presence of visitors."
Challis said zoos should be sensitive to the requirements of animals, and that exhibits can be designed to benefit both animals and humans.
He said, "Where it is necessary and relevant, efforts such as the maintenance of species in relevant social groups, off-show areas for retreat, restricted areas of viewing for visitors, sympathetic enclosure design with a knowledge of the species' biology in mind, use of closed-circuit television, or something similar, to show animals even if (they are) 'off-show,' are all relevant."
Following the study, the zoo installed camouflage netting to the viewing area of the gorilla enclosure, which seemed to help reduce some of the abnormal behaviors and infighting.
Name: Mountain Gorilla (
Gorilla gorilla beringei)
Primary Classification: Hominidae (Chimpanzees, Gorillas, Orangutans, and Humans)
Location: The Virunga volcanoes, which separate Zaire from Uganda and Rwanda.
Habitat: Montane tropical rainforest.
Diet: Mostly roots, leaves, and stems. Also bark, wood, roots, flowers, fruit, fungi, and invertebrates.
Size: Up to 6 ft in length and 450 lbs in weight.
Description: Black, long, silky fur. Hairless face, ears, hands and feet. Broad head with short muzzle. Prominent brow rdige. Wide, lared nostrils. Large jaw muscles, broad teeth and long canines. Small eyes and ears. Robust build. Long, muscular arms. Short legs. No tail.
Cool Facts: They are the world's largest primates. They are shy and retiring rather than aggressive, and will avoid conflict unless severely threatened. Dominant adult males develop a silver patch of hair on their backs; they are called silverbacks.
Conservation Status: Endangered
Major Threats: Deforestation, hunting and trophy poaching.
What Can I Do?: Visit
The Dian Fossey Gorilla Fund International, the
Mountain Gorilla Conservation Fund and the
Wildlife Conservation Society's Gorilla Conservation site for information on how you can help.
