EXTRA-PAIR COPULATIONS IN A MONOGAMOUS GIBBON (HYLOBATES LAR)

This study, conducted in a rainforest in Thailand, presents the first evidence for extra-pair copulations in white-handed gibbons - Asian ap es that live in monogamous groups. The ratio of in-pair copulations ve rsus extra-pair copulations as observed among three free-ranging, well -habituated groups was 88 versus 12 % and involved one adult paired fe male and three adult paired males. Extrapair copulations may be explai ned as an effort to breed with a partner of superior quality to the cu rrent mate and/or may be part of a strategy to forestall infanticide.