Observation on mating behavior and sexual play in the squirrel monkey (Saimiri sciureus)

Behavior patterns during play, sexual role differentiation dependant on age, and mating behavior in squirrel monkeys living in laboratory groups are described. While juveniles prefer mutual play (wrestling, contact play) adults or subadults most often use distinct roles at play; the male acts as the pursuer and the female flees but provokes his further pursuit. The male usually initiates the interaction by approaching, while the female determines what course it will follow (retreating or play or mating). True copulatory behavior occurs in a rather stereotyped manner. A sequence of 10–25 mounts with rapid, followed by slow and intense pelvic thrusts, terminates with ejaculation. Mounts with or without rapid thrusts may occur during play, but long series of slow thrusts characterize mating behavior. Between the mounts the female repeatedly displays genitals to the male and both partners purr to each other. An increase of urine washing and genital inspection may be observed but is not restricted to days when mating occurs. The influence of rank order among males on sexual behavior is discussed.