Abstract # 124:

Scheduled for Saturday, June 21, 2008 09:00 AM-09:10 AM: Session 13 (Meeting Room 2DEF) Oral Presentation

Owl monkeys don't just give a hoot: preferred food elicits trills

C. K. Wolovich1,2, S. Hooff1,2 and S. Evans2
1Bucknell University, Department of Biology, Lewisburg, PA 17837, USA, 2DuMond Conservancy for Primates and Tropical Forests, Inc.
     Nocturnal owl monkeys (Aotus spp.) forage within close proximity to other members of their family group. Given their omnivorous lifestyle and tendency to share food, owl monkeys would benefit by communicating information effectively about potential food items. Their vast vocal repertoire has only been vaguely described and there has been no previous experimental work to determine the function of their calls. Approximately two hours before sunrise, we presented eleven captive groups of owl monkeys (DuMond Conservancy, Miami, FL) with preferred and non-preferred food items (banana and cucumber respectively; presented in a counter-balanced order). We recorded the occurrence of various vocalizations (chirps, gruff-grunts, hoots, squeals, and trills). Rates of vocalizations during these trials were compared to those during control periods (when pieces of paper were presented and in the absence of any experimental stimulus). The occurrence of trills varied significantly across treatments, with the monkeys trilling most often in the presence of a preferred food item (median=1.2/min) and least often in the presence of the non-food item (median=0.00/min) [Friedman’s c2(3)=12.9, p=0.005]. We examined the acoustic properties of the trill, a call that is likely to function in communicating the value of a food item.