Postgraduate Profiles

Helen Dooley

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Thesis: The Behaviour of Kloss gibbons (Hylobates klossii) in the Peleonan forest, Siberut Island, Indonesia

Gibbons are arboreal apes that live in territorial, nuclear family groups in the rainforests of south Asia. Recent research has highlighted the behavioural variation that exists both between species and between populations of gibbons. My research is focused on the species Hylobates klossii (Kloss gibbon). Kloss gibbons are unique among the gibbons in several ways. All gibbons sing loud songs and in most species mated pairs duet however, Kloss gibbons do not. Additionally they are entirely black and lack the pelage variation of other species and they have been subject to human predation for roughly 2000 years in the absence of other predators common to gibbons. This makes them an interesting species to study because we can directly observe their anti-predator strategies (humans are their main predator). We can also evaluate the social factors that influence singing in males and females separately because they do not sing together. I have collected data on a previously unstudied population of Kloss gibbons in the Peleonan forest in the north of Siberut Island in Indonesia. I will compare the data I have for this population to observations from previous studies of other Koss populations and to other gibbon species.

Why my research is important

Aside from humans, gibbons are the only ape that exhibits a monogamous mating system. And like humans, monogamy in gibbons is flexible (polygyny and polyandry exist) and mature offspring may delay dispersal from the family territory to assist their parents in raising younger siblings. This makes them particularly interesting not just for the study of primate behaviour but also for understanding the factors influencing monogamy and family dynamics.


Adult male Kloss gibbon feeding on caterpillars

Feb 2007

Oct 2012