Abstract # 97:

Scheduled for Friday, August 19, 2005 09:30 AM-09:45 AM: Session 7 (Parliament Room) Oral Presentation

Seasonal patterns of ecology, behavior, and reproduction in Phayre's leaf monkeys

C. Borries, S. A. Suarez, P. Terranova and A. Koenig
Department of Anthropology, Stony Brook University, Circle Rd., SBS Bldg. S-515, Stony Brook, NY 11794-4364, USA
     The timing of reproductive events in nonhuman primates is usually linked to favorable periods maximizing female reproductive success. Disparity seems to exist, however, across geographical areas and primate taxa regarding the importance of energetic constraints on conception, lactation, and weaning. This study presents first long-term data on weather and the corresponding seasonality of feeding, ranging and reproduction in wild Phayre’s leaf monkeys (Trachypithecus phayrei) at Phu Khieo Wildlife Sanctuary, Northeastern Thailand. Weather data were recorded since January 2001. Demographic records have been kept since December 2000 for 25 adult females and their offspring. Daily travel distance (GPS) and general activity data (30-min scan sampling) were collected monthly since March 2004 for three groups. Most births occur in the dry season between December and April (> 90%) indicating a peak in conceptions between June and October, the second half of the rainy season. Based on ranging, activity, and diet the conception period appears to be energetically the most favorable time of the year. Weaning (i.e., cessation of nipple contact) peaks later in the year when conditions are less favorable. These results indicate that the energetic conditions around conception may be crucial for the timing of reproductive events in Phayre’s leaf monkeys, a situation found in other Asian and Malagasy primates as well. Supported by NSF (BCS-0215542).