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 […]

Orangutans’ color preference for food items

The effects of the addition of color to a dry primate diet on the feeding behavior of orangutans were studied. Purina Monkey Chow was dipped in food coloring (red, green, blue, orange). Colored and plain chow was offered to the subjects, three adults, and two juveniles. Time to eat or lose interest in feeding, quantity, […]

Social learning by orangutans (Pongo abelii and Pongo pygmaeus) in a simulated food-processing task

Increasing evidence for behavioral differences between populations of primates has created a resurgence of interest in examining mechanisms of information transfer between individuals. The authors examined the social transmission of information in 15 captive orangutans (Pongo abelii and Pongo pygmaeus) using a simulated food-processing task. Experimental subjects were shown 1 of 2 methods for removing […]

Piagetian Liquid Conservation in the Great Apes (Pan paniscus, Pan troglodytes, and Pongo pygmaeus)

An understanding of Piagetian liquid conservation was investigated in 4 bonobos (Pan paniscus), 5 chimpanzees (Pan troglodytes), and 5 orangutans (Pongo pygmaeus). The apes were tested in the ability to track the larger of 2 quantities of juice that had undergone various kinds of transformations. The accuracy of the apes’ judgment depended on the shape […]

Computer-assisted enrichment for zoo-housed orangutans (Pongo pygmaeus)

The study of environmental enrichment has identified a variety of effective forms of enrichment, but there are widespread problems associated with their use. Few forms of enrichment are cognitively challenging, and even the most effective often result in rapid habituation. This study examined the use of a computer-joystick system, designed to increase in complexity with […]

Technology at the Zoo: The Influence of a Touchscreen Computer on Orangutans and Zoo Visitors

A computer-controlled touchscreen apparatus (hereafter referred to as “touchscreen”) in the orangutan exhibit at Zoo Atlanta provides enrichment to the animals and allows cognitive research to take place on exhibit. This study investigated the impact of the touchscreen on orangutan behavior and visibility, as well as its impact on zoo visitors. Despite previous research suggesting […]

Second and Third-Generation Zoo Exhibits: A Comparison of Visitor, Staff, and Animal Responses

The present study compared visitor, staff, and animal responses to two second-generation and two third-generation exhibits that displayed the same species of animals-Bornean orangutans and Pigmy chimpanzees-at the San Diego Zoo. Four methods were used to assess responses to the two types of exhibits: behavior mapping, timing, a visitor questionnaire, and staff interviews. Attitudinal measures […]

Supplemental material for Orangutans (Pongo pygmaeus and Pongo abelii) understand connectivity in the skewered grape tool task

Great apes appear to have limited knowledge of tool functionality when they are presented with tasks that involve a physical connection between a tool and a reward. For instance, they fail to understand that pulling a rope with a reward tied to its end is more beneficial than pulling a rope that only touches a […]

Image Scoring in Great Apes

‘Image scoring’ occurs when person A monitors the giving behaviour of person B towards person C.We tested for ‘image scoring’ in chimpanzees, bonobos, gorillas, and orangutans. Subjects passively observed two types of incident: (i) a ‘nice’ person gave grapes to a human beggar, and (ii) a ‘nasty’ person refused to give. The subject witnessed both […]

Methods for calculating activity budgets compared: a case study using orangutans

The results of comparisons of behavioral data between individuals, age–sex classes, seasons, sites and possibly even species may depend on sample size and the computational method used. To establish whether these are valid concerns, we compared results for percentage time spent feeding on major food types (fruit, leaves, flowers, invertebrates, bark, pith and other) for […]