The gorilla exhibit area in Lincoln Park Zoo. Photo from Things You Should Do.
One of the chimpanzee from the study, Kipper (now deceased), from Lincoln Park Zoo interacting with a child. Photo by Chicago Tribute.Holding and exhibit areas differ in size, design and functionality. A study by Ross and Lukas on 11 AZA-accredited zoos shows that holding areas are usually about 40 times smaller than exhibit areas (Ross et al., 2010). At the Lincoln Park Zoo, the holding area is about 9.3% of the size of the exhibit area (for both gorillas and chimpanzees). Whereas the exhibit area is designed for the complexity and to mimic the natural environment of its animal inhabitant, the holding area is usually designed for simplicity and functionality to meet husbandry needs.
Seven gorillas (2 males, 5 females; N = 7) and seven chimpanzees (3 males, 4 females; N = 7) were observed in this study. I should point out that the authors of the study is by no means criticizing Lincoln Park Zoo. It is an informal observation of behavioral changes for these animals in different environment. The result of the study shows that:
Inside the holding area - Increased locomotion and affiliative behavior. Also showed increased rates of aggression, self-directed behavior (subject touches, manipulates or examines the body, skin, or hair) and solitary play. Were in close proximity with each other.
Inside the exhibit area - Increased feeding and foraging behavior and also sexual behavior.
Inside the holding area - Increased aggression. Increased rate of scratching and self directed behavior (subject touches, manipulates or examines the body, skin, or hair). Were in close proximity with each other.
Inside the exhibit area - Increased feeding and foraging behavior.
Schematic representation of a typical holding area suite for an individual chimpanzee or gorilla social group at the Regenstein Center for African Apes. Shaded areas indicate animal enclosures; noncolored areas are sections of human activity (caretakers and data collectors). (Ross et al., 2010)
Both gorillas and chimpanzees showed increased aggression accompanied with self directed behavior when inside holding area. Increase in aggression can sometimes be attributed to overcrowding and self directed behavior generally means that an animal is nervous. Being constrained in a smaller space increases the chance of mixed-sex and mixed-dominance encounters thus resulting in agonistic and submissive observations. When inside exhibit areas, both apes exhibited an increase in feeding and foraging behavior. This presumably is due to their feeding and foraging habit in the exhibit area. If I remember correctly, one of the major breakthrough in exhibiting apes (and most animals) is to encourage foraging behavior throughout the day. It is no surprise that these apes exhibit these behaviors.
Chimpanzee subjects in a single enclosure in a holding area suite, during a period of free access (following training and research protocols). Photograph was taken from the central caretaker area. (Ross et al., 2010)
These apes reacted differently when inside their holding area than in their exhibit area because they are exposed to different sensory. Apart from the difference in size and complexity, these two areas also differ in the degree of human interaction, cross-species presence, environmental factors and time spent between these two areas. An understanding of these differences and motivational factors is important in promoting optimized environments for captive apes. The authors encourage that zoos would consider species-specific functional, physical and social preferences when designing enclosures for apes regardless of frequency of use.
Ross, S. Wagner, K. Schapiro, S. Hau, J. 2010. Ape behavior in two alternating environments: comparing exhibit and short-term holding areas. American Journal of Primatology 72: 951–959. doi: 10.1002/ajp.20857