Understanding visual barriers: evidence for Level 1 perspective taking in an orang-utan, Pongo pygmaeus

An adult female orang-utan used an untutored series of physical manipulations to guide humans to food placed beyond her reach. Through a series of experiments that involved different visual occlusions, this orang-utan appeared to take into account humans’ visual states when using them to retrieve inaccessible goals. These data suggest that she was able to […]

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, […]

Individual Response Strategies in List Learning by Orangutans

Two orangutans learned eight lists of items in a recognition memory procedure that allowed the list items to be reported in any order. In a previous study using this same procedure, the orangutans developed a spatial response strategy that was applied to acquisition of novel lists. The purpose of the present study was to determine […]

Response strategies inlist learning by orangutans (Pongo pygmaeus × P. abelii)

Rhesus monkeys (Macaca mulatta) develop strategies to acquire and execute serial lists (K. B. Swartz & S. A. Himmanen, 2001). Serial probe recognition studies of list memory have demonstrated similarities across monkeys and humans (S. F. Sands & A. A. Wright, 1980). The present study extended the investigation of list learning and memory to determine […]

Captive and wild orangutan (Pongo sp.) survivorship: a comparison and the influence of management

For managers of captive populations it is important to know whether their management provides a species with the physical and social environment that maximizes its survivorship. To determine this, survivorship comparisons with wild populations and long-term evaluations of captive populations are important. Here we provide both for orangutans. We show that survivorship has increased during […]