Ejaculation by male rhesus in the absence of female partners

The number of ejaculatory plugs found beneath the cages of male rhesus over a 14-month period indicated a high incidence of ejaculation in the home cage in the absence of a female partner. Frequency of ejaculation in the home cage was not related to concurrent tests of sexual behavior with receptive females. Moreover, ejaculation in the home cage within 22 hr or less of sex tests did not affect the frequency of ejaculation in tests with stimulus females. Long- and short-term vasectomized males ejaculated as frequently in their home cages as nonvasectomized males. No ejaculatory plugs, of course, were found beneath the cages of males castrated 2 years earlier.