Abstract # 98:

Scheduled for Friday, August 19, 2005 09:45 AM-10:00 AM: Session 7 (Parliament Room) Oral Presentation

Prominent swellings in silvered langurs: What do they indicate?

N. Shelmidine1,2, C. Borries2 and C. McCann1
1Wildlife Conservation Society, 2300 Southern Blvd., Bronx, NY 10460, USA, 2Department of Anthropology, Stony Brook University
     Numerous hypotheses have been proposed to explain exaggerated sexual swellings in female primates. They have been interpreted as ‘honest’ or ‘deceptive’ indicators of ovulation. In some species, however, swellings are non-exaggerated (confined to the vulva) and called prominent. We investigated the occurrence of prominent swellings throughout the reproductive cycle in silvered langurs (Trachypithecus cristatus ultimus) to determine whether they function as a ‘honest’ or ‘deceptive’ indicator of estrus, or whether they might be a hormonal by-product. Data were collected from November 2002 through March 2004 during 2,948 hours on nine adult females of a one-male/multi-female group housed at the Bronx Zoo. All occurrence sampling of the frequencies of sexual behavior and male inspections transpired daily from six-hours of videotaping. The degree of swelling was assessed on a 3-point scale. In cycling females, swellings occurred during estrus as well as during non-estrus periods and a Chi Square test determined that male interest was independent of swellings. A G-test indicated that swellings were significantly more frequent and lasted longer during gestation than during any other reproductive state. Thus, prominent swellings do not seem to indicate estrus in silvered langurs. They might be induced by progesterone as they occur more frequently towards the end of the gestation period when progesterone values usually are highest. Future hormonal analysis could clarify this issue. Supported by Wildlife Conservation Society (#SSF 03-A6-SG).