Student Prize Award Abstract
1998 Oral Paper Award

SOCIAL BEHAVIOR AND SEXUAL MOTIVATION ACROSS THE REPRODUCTIVE CYCLE IN TITI MONKEYS (CALLICEBUS MOLOCH): CONCEALMENT OR COMMUNICATION OF OVULATION?

D.M. Reeder(1,2), S.P. Mendoza(1,2), and W.A. Mason(2). (1)Department of Psychology, and (2)California Regional Primate Research Center, University of California, One Shields Avenue, Davis, CA 95616.

Concealment of ovulation in monogamous females has been posited as a mechanism that impels males to remain with their partners in order to ensure paternity. This study explored social behavior and sexual motivation across the reproductive cycle in the monogamous titi monkey (Callicebus moloch) to examine whether ovulation is communicated or concealed. Subjects were six adult laboratory-born females, their mates, and other males. Socio-sexual behaviors were assessed across the ovulatory cycle in three conditions: 1) home cage with mate, 2) replica of home cage with mate or other male, and 3) choice test with mate and other male. Urine samples were collected 4-6 times per week to assess reproductive cyclicity. Females preferred their mates in choice tests and spent more time in proximity with them than with another male. Pairmates approached one another at an equal rate. When the female was with another male, however, he nearly always initiated approaches, and she nearly always moved away from him. These measures were not altered by the female's reproductive state. While animals copulated during all possible reproductive states, sex was more frequent than expected during the periovulatory period. It is likely that a sharp dichotomy between communication or concealment of ovulation is an oversimplification, and that finer analysis and experimentation is needed to elucidate the true nature of this phenomenon.