Theses and Dissertations

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End date: 2022Subject: search.filters.subject.Hoolock gibbon

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    Social Behaviour and Duetting in Hoolock Gibbons in Gibbon Wildlife Sanctuary, Assam
    (Wildlife Institute of India, Dehradun, 2009) Sankaran, Sumithra; Rawat, G.S.; Kumar, R.S.
    The hoolock gibbon (Hoolock hoolock), only anthropoid primate found in India, is a pair-living, territorial species, which duets extensively. Various hypotheses regarding the function of this behaviour in monogamous primates include territory advertisement, pair-bonding, mate defense, resource defence and group cohesion. This study aimed to understand the nature of social behaviour of this species, and how duetting fits into the repertoire of social behaviour seen in this animal. Three groups of Hoolock gibbons were habituated and studied intensively over a three month period. Relationships between the different group members were explored, alongside time budgets of various activities of the adult pair, the synchrony in their behaviour and frequency and nature of all affiliative and agonistic behaviours. Relationships between territory sizes, group sizes, frequency of duetting and nature of other social interactions have been examined in detail. A considerable amount of individual difference were found between the different study animals in their interactions with other group members. These animals display complex affiliative interactions with rare displays of aggression. It was found that although the proportion of time spent in social interactions was comparable between the three groups, the proportioning of this total time among different social interactions may vary considerably. The primary difference was found to be in allogrooming interactions with the proportion of time time spent increasing with increase in group size. The study also found considerable evidence for the possible existance of male-care in this species.
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    Food selection and ranging in hoolock gibbon (Hylobates hoolock Harlan 1834) in Borajan reserved forest, Assam
    (Wildlife Institute of India, Dehradun, 1997) Kakati, Kashmira; Sathyakumar, S.
    This study on food selection and ranging in the hoolock gibbon (Hylobates hoolock ,Harlan 1834) was carried out between December 1996 and April 1997 in Borajan Reserve Forest, a disturbed and fragmented patch of remnant tropical evergreen forest in Upper Assam, India. The hoolock gibbon is a primarily frugivorous species, confined to closed-canopy evergreen forests of North-east India, Bangladesh and Burma. This type is highly endangered in its entire range. Threats to the continued existence of the hoolock are from large-scale destruction of its habitat and hunting. Two troops of gibbons were followed intensively for four months and behavioural data were collected by continuous focal animal observations. Data were also collected ad libitum on a third troop. Data on the structural components of the vegetation and on the availability of food resources in the Intensive study area were collected systematically. The results of the study show that food availability influenced the diet, movement patterns, home-range sizes and behaviour of hoolock gibbons. Gibbons were selective in their diet using only forty-three plant species out of the more than two-hundred species present. Figs constituted important keystone resources for the gibbons. In months of low fruit availability, the gibbons had a predominantly folivorous diet. Home ranges were small (10.4 ha and 5.4 ha) and habitat degradation represents the greatest threat to the gibbons