Abstract # 85:

Scheduled for Friday, June 22, 2012 10:30 AM-10:45 AM: Session 11 (Magnolia) Oral Presentation


A. I. Stone
Eastern Michigan University, Department of Biology, Ypsilanti, Michigan 48197, USA
      Squirrel monkeys live in large groups and are seasonal breeders. The unique reproductive physiology of males is suggestive of sexual selection. Males show weight gain during the mating period, which produces a "fatted" appearance in the upper body. Although much is known about the physiology of fatting, its ecological function remains unknown. In addition, little is known about the basic mating patterns of squirrel monkeys. Here I report observations on Saimiri sciureus in Brazil, in order to describe the mating patterns of this species, and to examine the hypothesis that male fatting is a product of sexual selection. Males were observed via focal animal sampling during 3 mating seasons. Behaviors such as branch sniffing, genital sniffing and “draping” were observed. Triads of two males and a female were common (48% of triads observed), often involving agonism between the males. The 2-month mating season accounted for 62% of all male–male agonism observed over 12 months (p<0.05). These results are suggestive of male-male competition for females. On the other hand, triads of two females following a male were also observed (8% of observations). Males did not coerce females. These results are also suggestive of female choice. Continuing work will address whether male fatting leads to higher reproductive success, and if so, whether it operates via male-male competition, female choice, or both.