Abstract # 2072 Event # 116:

Scheduled for Friday, August 18, 2006 11:45 AM-12:00 AM: Session 10 (Regency East #2) Oral Presentation

Demographics and ranging of floaters in socially monogamous owl monkeys (Aotus azarai)

E. Fernandez-Duque1, A. Di Fiore2,3, M. Rotundo4 and C. Juárez4
1University of Pennsylvania, Department of Anthropology, Philadelphia, PA 19104, USA, 2Department of Anthropology, New York University, 3New York Consortium in Evolutionary Primatology, 4Fundación ECO, Formosa, Argentina
     Owl monkeys have always been reported to live in small social groups composed of an adult heterosexual pair, one infant and one or two individuals of smaller size. More recently, we found that as much as 25-30% of adults in one population of Aotus azarai in Northeastern Argentina range solitarily. To describe the age and sex structure of this floater population we captured 10 males and 10 females, fitted them with radio-collars and regularly observed them as they dispersed from their natal group and/or entered into a new group. To evaluate their ranging patterns, we estimated the minimum distance traveled during the night twice a month during a year, once with full moon and once with new moon. Floaters were young adults probably looking for a reproductive opportunity after natal dispersal or relatively older adults evicted from their groups by incoming floaters. During dispersal the floaters ranged over the territories of various social groups for periods that varied from a few weeks to a year, concentrating most of their ranging during nights of full moon. Given that it took several years of fieldwork to confirm the existence of a floater population, it remains possible that these less conspicuous solitary individuals will be detected in other populations of small and cryptic monogamous species like titi (Callicebus) or saki monkeys (Pithecia) as more long-term studies of identified individuals are conducted.