Abstract # 150:

Scheduled for Friday, June 21, 2013 07:00 PM-09:00 PM: Session 21 (SG Foyer ABC) Poster Presentation


S. E. Henley, M. A. Shender, K. E. Wagner and S. R. Ross
Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, IL 60614, USA
     The typical social grouping of Western lowland gorillas (Gorilla gorilla gorilla) is a harem group composed of one adult male, multiple females and their offspring. There is a nearly equal birth sex ratio in zoos, and since young males are often incompatible with the resident silverback of a harem group, a resulting “surplus” of males has formed in captivity. This has caused an animal management conundrum. Recently, this issue has been addressed with the formation of all-male bachelor groups. However, there remains relatively little empirical information about behavioral patterns within these groupings due to the novelty of the configuration. This study examined the behavior of three immature males during the first four months following their introduction as a bachelor group at the Lincoln Park Zoo (Chicago, IL). We found that prosocial behavior (social play, groom) increased over this time period (r=0.021, p=0.005), but no other behaviors significantly changed in these first four months (i.e. sexual, abnormal, agonistic, object, solitary, and feeding). The increase in prosocial behavior demonstrated indicators of increased social stability within the group, and may indicate that the young gorillas adjusted to their new social conditions relatively quickly. These results provide preliminary support for the strategy of integrating young males together in order to form stable, long-term groups and inform managers seeking behavioral indicators of a successful bachelor group introduction.