An investigation into keeper opinions of great ape diets and abnormal behaviour

Zoos are evidencing a shift in great ape diets to cultivated fruit-free to achieve a more wild-type nutritional composition (lower sugar, higher fibre). This study aimed to ascertain great ape keeper knowledge and opinions on the removal of cultivated fruit from great ape diets, to investigate feeding regimes currently in use and to understand the […]

Gorillas (Gorilla gorilla gorilla) Fail to Learn Abstract Cues of Differential Outcomes in a Novel Cognitive Bias Test

In order to assess mood state in three male western lowland gorillas housed in a bachelor group, we developed a novel version of a cognitive bias task. The background color of a touchscreen presented a conditional ‘if, then…” rule relating to outcomes involving differential amounts of food rewards. The gorillas struggled to reach a criterion […]

Visitor effects on anxiety in two captive groups of western lowland gorillas

There is growing interest in examining the effects that visitors have on the welfare of zoo primates. Most recently, the importance of evaluating the combined impacts of visitors and management practices on anxiety levels of these animals has been highlighted. Studies that take such an approach have the potential not only to highlight how visitors […]

Color preferences in gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes)

Color plays an important biological role in the lives of many animals, with some species exhibiting preferences for certain colors over others. This study explored the color preferences of two species of ape, which, like humans, possess trichromatic color vision. Six western lowland gorillas, and six chimpanzees, housed in Belfast Zoological Gardens, were exposed to […]

Further Developments in the Breeding Population of Lowland Gorillas at Apenheul

In 1987 a second group of lowland gorillas was formed at Apenheul. Aspects of the zoo-technical management (diet, accommodation, etc.) are described. The management and the development of the population, including mother-rearing of all offspring, are described. Special attention is given to the formation of a second group by introducing two zoo-born females and a […]

A note on the influence of visitors on the behaviour and welfare of zoo-housed gorillas

Visitors to zoos can be a source of potential stress to some captive-housed primates. To date, the effect of the human audience on the welfare of captive gorillas has been overlooked. This study thus examined the behaviour of six zoo-housed gorillas during periods of both high and low visitor density, to establish whether there was […]

Mountain gorilla life histories, reproductive competition, and sociosexual behavior and some implications for captive husbandry

Abstract 10.1002/zoo.1430090302.abs New data on modal patterns of, and variability in, mountain gorilla life history tactics and sociosexual behavior, collected during long-term fieldwork at the Karisoke Research Centre, are presented here. These data show that immature males and females develop sociosexual relationships with both peers and adults, and that these relationships—which contribute to more complex […]

Token transfers among great apes (Gorilla gorilla, Pongo pygmaeus, Pan paniscus, and Pan troglodytes): Species differences, gestural requests, and reciprocal exchange

Great apes appear to be the nonhuman primates most capable of recognizing trading opportunities and engaging in transfers of commodities with conspecifics. Spontaneous exchange of goods between them has not yet been reported. We tested gorillas (Gorilla gorilla), orangutans (Pongo pygmaeus), bonobos (Pan paniscus), and chimpanzees (Pan troglodytes) in a token-exchange task involving two conspecifics […]

Relative numerousness judgment and summation in young and old western lowland gorillas

The relationship between age, relative numerousness judgment, and summation was investigated in 11 Western lowland gorillas (Gorilla gorilla gorilla). Experiments 1 and 2 evaluated the gorillas’ ability to select the larger of 2 food quantities before and with training. The majority of gorillas did not reliably select the larger quantity in Experiment 1 until receiving […]

Imitative learning by captive western lowland gorillas (Gorilla gorilla gorilla) in a simulated food-processing task

Although field studies have suggested the existence of cultural transmission of foraging techniques in primates, identification of transmission mechanisms has remained elusive. To test experimentally for evidence of imitation in the current study, the authors exposed gorillas (Gorilla gorilla gorilla) to an artificial fruit foraging task designed by A. Whiten and D. M. Custance (1996). […]