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An ecobehaviuoral study of Phayre’s leaf monkey Trachypithecus phayrei (Blyth, 1847)

An ecobehaviuoral study of Phayre’s leaf monkey Trachypithecus phayrei (Blyth, 1847)
Joydeep Bose


Department of Zoology, Gauhati University, Guwahati 781 014, Assam, INDIA.


One of the least studied primates, the Phayre’s leaf monkey (PLM), Trachypithecus phayrei is restricted in its distribution in India to the states of Tripura, Assam and Mizoram The Indian subspecies is the Trachypithecus phayrei phayrei._Apart from Primary forests, it is found to exist in bamboo dominated habitat as well as in plantation areas. Though some works on distribution, ecology and behaviour of this species are available, no long-term study has been carried out on the species simultaneously covering the different habitat setups in Assam and Tripura, which is essential for developing a conservation action plan for the survival of the species.

The present study has been initiated to cover the lacunae-in the eco-behavioural study of the PLM in its different distributional ranges in prevailing diverse habitat setups in Northeast. The present study is aimed to understand the behavioural responses of the PLM in different habitat conditions, which are now prevalent in its distribution range in India. This study will cover: a) the present distribution range of PLM in India; b) to study the social dynamics of PLM; c) to evaluate the population structure; d) to study the pattern of ranging; e) pattern of the allocation of time in different essential behavioural components; f) Identify the food plants and feeding pattern and g) develop an action plan for the conservation of the species.

The Phayre’s leaf monkey is reported from India, Myanmar, Bangladesh, China, Vietnam, Laos, and Thailand. In India, it’s current known distribution is confined to the states of Assam, Tripura and Mizoram.

The Phayre’s leaf monkey was found to be confined to southern Assam in the districts of Cachar, Karimganj and Hailakandi in both Reserve Forests (Innerline, Patharia, Tilbhum and Longai) and forested patches within tea gardens (Silcoorie , Borojalenga and Irongmara). Former confirmed reports of distribution of the species in Assam were from Innerline RF only. The survey thus added three RFs to the distribution range of the species. All the tea estates where the PLM was sighted are new reports. The Silcoorie tea estate was determined to be the northernmost distribution site of the species in India. The distribution record of the species in Mizoram was confined to Dampa tiger Reserve and Ngengpui WLS. The present survey added Murlen NP, Lengteng WLS, and Khawnglung WLS to the distribution record.

The important findings of the surveys were: 1) Discovery of-new sites of die occurrence of the PLM in Assam and Mizoram; 2) Determination of the northern most distribution site (Silcoorie T. E. in Cachar district of Assam) of the species in India; 3) Distribution of the species is within Protected areas (Wildlife sanctuary), Reserve forests as well as tea garden areas under private jurisdiction; 4) Occurrence of the species in different kinds of habitat; including sub-tropical evergreen and even sub-montane forests also and 5) Majority of sites where the PLM was sighted in Assam were either in fragmented or continuous secondary bamboo dominated forest patches near human habitations.

The present study yielded information on ecology and behaviour of the PLM in two different habitat setups. Both the habitat setups are representative current realities in the states of Assam and Tripura, where primary forests are gradually giving way to secondary forests-somewhere bamboos taking over and others where plantations are being done.