Mark Challis, acting zoo manager at Belfast Zoological Gardens, says he agrees with Wells that humans might affect some animals. Some zoos play classical music to drown out visitor noise (Image: iStockphoto) She adds that some zoos even play classical music, which seems to soothe the animals and drown out visitor noise. 'Primates are more likely to be excited by zoo visitors if they appear in large numbers, display erratic behaviours, elicit high levels of noise or deviate greatly from the norm in terms of their physical appearance, for example height, clothing,' says Wells. Since it is hard to know when zoos will be busy or not, she says factors other than visitor group size could lessen the possible human impact. Wells says visitors can affect all primates, not just gorillas. When the zoo was crowded, the gorillas often banged on the viewing window, exhibited all of the abnormal behaviours, repeatedly groomed themselves and fought more often. Visitors seemed to have no effect on basic behaviours, such as standing, walking and socialising.īut when there were few visitors the gorillas tended to relax and rest more. She also recorded abnormal behaviour, like repetitive teeth clenching, body rocking and spinning. The gorillas were also observed on 20 quiet days, usually on weekdays when an average of six people visited the zoo.ĭuring these periods, Wells documented known gorilla behaviours, such as standing, sitting, resting, grooming, aggression, playing, walking, running, climbing, socialising and banging on the viewing window. The gorillas were observed for four hours a day on 20 busy days, when the average number of visitors was around 1288. The gorilla group includes both wild-born and captive-born males and females of different ages. Wells, a senior lecturer in the School of Psychology at Queen's University Belfast, studied six western lowland gorillas housed together at Belfast Zoological Gardens. 'We noticed more behaviours suggestive of relaxation, such as increased resting, during low visitor density, and more behaviours suggestive of agitation, such as repetitive rocking, group-directed aggression and self-grooming during high visitor density,' says the study's author, Dr Deborah Wells. The research, published in the September issue of the journal Applied Animal Behaviour Science, is the first analysis on the influence of visitors on the behaviour and welfare of zoo gorillas. Gorillas in zoos become agitated and anxious when large numbers of people approach their exhibit, new research suggests. Are you looking at me? (Image: iStockphoto)

Angry giant gorilla