Physiological changes during copulation in male and female stumptail macaques (Macaca arctoides).

Radiotelemetric recordings were made of uterine contractions in female stumptail macaques, and of heart and respiratory rate in stumptail monkeys of both sexes, before, during and after copulation. These data were fed into a multichannel recorder, along with a spoken record of behavioral changes. Males' heart and respiratory rates were raised during penile thrusting, reached a peak and then fell sharply after ejaculation. Uterine movements were similar during successive copulations. After uterine movements associated with penile thrusting prior to ejaculation a rise in contraction force occurred which lasted about 15 seconds. It is in this period, if ever, that a climax face was displayed by the female. The female's look-back and reach-back behaviors were not linked to either the pattern of uterine contractions or the occurrence of the climax face.