TESTICULAR FUNCTION AND SCROTAL COLORATION IN PATAS MONKEYS

Patas monkeys (Erythrocebus patas) have aquamarine-coloured scrota, bu t data are unavailable regarding the potential connection between chan ges in scrotal coloration and testicular function. In the rhesus monke y (Macaca mulatta), seasonality of mating is accompanied by an intensi fication of red colour of the scrotum and a doubling of testicle size. A one-year study of male patas monkeys was undertaken in order to exa mine potential seasonal correlates of testicular function and scrotal colour. Increases in testosterone concentrations and testicular volume occurred during the mating season in adult males, but scrotal colour was fairly uniform throughout the year. Neither age, body weight, nor health influenced scrotal colour. These findings contradict the sugges tion that the sex skin of seasonally breeding primates will become mor e intense during the mating season as a result of elevations in steroi d hormone levels. Evidence from held studies in Africa suggest that th e colour is part of a constellation of traits involved in male competi tion for mates.