Abstract # 7955 Event # 212:

Scheduled for Monday, August 28, 2017 01:45 PM-02:00 PM: (Grand Ballroom) Oral Presentation


MIXED EVIDENCE FOR ECOLOGICAL RISK AVERSION IN JUVENILE WILD CHIMPANZEES (PAN TROGLODYTES SCHWEINFURTHII) AT GOMBE NATIONAL PARK, TANZANIA

J. C. Winans1, K. R. Wellens1, E. V. Lonsdorf2 and C. M. Murray1
1George Washington University, 800 22nd St NW, Suite 6000, Washington, DC 20052, USA, 2Franklin and Marshall College
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     The ecological risk aversion hypothesis (ERAH) proposes that prolonged primate juvenescence is a response to predation and starvation risks. To avoid predation, juveniles maintain close proximity to adults, increasing competition and limiting foraging efficiency. Slow growth minimizes juveniles’ metabolic needs, diminishing subsequent starvation risk. However, past studies investigating the ERAH in wild primates have yielded mixed results. Here, we use 26 months of observational data from Gombe National Park, Tanzania to test the ERAH in wild chimpanzees by comparing the time juveniles spent in close proximity to conspecific adults while feeding and resting. Because predation risks theoretically decrease with increased body size, we predict that juvenile proximity to adults will decrease as they age. Additionally, we expect juveniles to spend more time in close proximity to adults while feeding and resting terrestrially than arboreally because the ground likely poses higher predation risk. Contrary to our predictions, juvenile proximity to adults increased with juvenile age (F1,12.21=15.12; p=0.02). However, supporting our predictions, juveniles spent more time in close proximity to adults while resting terrestrially than arboreally (F1,52.97=7.51; p=0.01), but not while feeding (F1,51.97=1.08; p=0.30). This pattern suggests that resting may be riskier than feeding, when individuals are upright and may be more vigilant for conspecific competition and predators. Other factors, such as social opportunities and resource distribution, may also contribute to patterns of juvenile proximity to adults.