Masturbation was observed in 9 of 52 captive adult Hylobates (gibbons)
over a period of 17 years at the International Center for Gibbon Stud
ies (ICGS). Four females and 5 males masturbated with varying degrees
of regularity. The behavior may be related to a disruption in early re
aring experiences of Hylobates. This is the first report on masturbati
on in these animals and documents that this behavior occurs infrequent
ly in captive Hylobates. (c) 1994 Wiley-Liss, Inc.