Abstract # 121:

Scheduled for Friday, June 22, 2007 03:00 PM-03:15 PM: Session 13 (North Main Hall F/G) Oral Presentation

Do Seasonal Changes Affect Activity in Captive Chimpanzees (Pan troglodytes) and Gorillas (Gorilla gorilla gorilla) Living in a Northern Zoo?

V. M. Vreeman and S. R. Ross
Lincoln Park Zoo, The Lester E. Fisher Center for the Study and Conservation of Apes, 2001 N. Clark, Chicago, IL 60014, USA
     In the wild, activity levels in chimpanzees and gorillas can be influenced by ecological, demographic, social, and cultural factors. Seasonality, such as the presence of a dry wet season, can affect food abundance and quality which can result in changes in foraging behaviors and activity levels. However, in well-managed captive settings, factors such as food abundance and group composition often remain relatively constant throughout the year. We might therefore look for other factors influencing behavior in captive settings. To examine the potential effects of seasonality on captive apes we observed 26 individuals (n=12 chimpanzees, n=14 gorillas) over a period of 25 months (2,366 hours total). Data were collected by instantaneous focal animal sampling on individuals living in naturalistic indoor/outdoor settings experiencing distinct temperature fluctuations. Repeated measures t-tests were used and criterion for significance was set at 0.05. We found both chimpanzees and gorillas were significantly more active in the winter months than any other season. In order to address whether these changes were a result of temperature, we compared seasons with relatively similar mean temperatures (spring and fall). We found no significant difference in activity levels for either species between these seasons. A number of potential factors that may influence activity levels include access to outdoor yards and visitor density which may affect the management of captive apes.