Abstract and Summary
Free-ranging woolly spider monkeys of both sexes deposit urine on the hand, foot or tail. The eliciting stimulus for this behavior in females is unknown. In males, it frequently appears to be the presence of a sexually receptive female or copulatory activity. Male and female woolly spider monkeys do not associate on any habitual daily basis and individual females may forage alone rather than with conspecifics. Given this fluid pattern of social structure, the most important function of urine washing for a female woolly spider monkey may be to advertise her state of sexual receptivity to any males passing over her foraging path. Males may use urine to facilitate individual recognition.