STATUS OF FOUR ARBOREAL SPECIES OF MAMMALS IN DARJEELING DISTRICT, WEST BENGAL, INDIA

To ascertain the present status of four arboreal species of mammals viz., Rhesus Macaque, Macaca mulatta (Zimmermann), Assamese Macaque, Macaca assamensis (M'Clelland), Common Langur, Senlnopithecus entellus (Dufresne) and Malayan Giant Squirrel, Ratufa bicolor gigantea (M'Clelland) in North Bengal, a project was undertaken by the Zoological Survey of India. The project was taken up for the following reasons (i) to ascertain their abundance, (ii) to add information at National level about their population and lastly, (iii) to collect data to built up comparative behavioural and demographic studies. The knowledge about the popUlation status of primates is a prerequisite to formulate any management plan or to carry out meaningful long-term behavioural studies. Therefore, this population survey may add some information to primate resources in India.


INTRODUCTION
To ascertain the present status of four arboreal species of mammals viz., Rhesus Macaque, Macaca mulatta (Zimmermann), Assamese Macaque, Macaca assamensis (M'Clelland), Common Langur, Senlnopithecus entellus (Dufresne) and Malayan Giant Squirrel, Ratufa bicolor gigantea (M'Clelland) in North Bengal, a project was undertaken by the Zoological Survey of India. The project was taken up for the following reasons (i) to ascertain their abundance, (ii) to add information at National level about their population and lastly, (iii) to collect data to built up comparative behavioural and demographic studies. The knowledge about the popUlation status of primates is a prerequisite to formulate any management plan or to carry out meaningful long-term behavioural studies. Therefore, this population survey may add some information to primate resources in India.
The distribution of these four arboreal species of mammals in India has been given below (vide Alfred et al., 2000).

STATUS OF NON-HUMAN PRIMATES
Amongst non-human primates Rhesus Macaque, Macaca mulatta, Assamese Macaque, ' Macaca assamensis and Common Langur, Semnopithecus entellus are the more common species.
Rhesus Macaque and Hanuman Langurs are widely distributed in Indian subcontinent but the Assamese Macaque is restricted in its distribution in the northeastern states. They are found living in feral condition and also as commensal around human settlements, in the towns and villages as opposed to their forest dwelling populations that were quite sizeable in our country. The people treated these rural and urban populations with tolerance on religious and ethical grounds. However, under increased economic pressure the traditional tolerance of the people tend to become eroded and in turn resulted in confrontation, which put the population under severe stress of survival.
In addition to this the commercial trade of Rhesus and Assamese Macaque for use in biomedical research especially in developed countries, and similar but relatively recent usage of Hanuman Langur for such purposes within the country resulted in their general popUlation decline.
In order to ensure proper conservation of these species it soon became necessary to collect baseline data on several aspects. So, the present status of the population of these species, their major habitat use, the significant ecological factors affecting their survival, needed to be studied for their conservati on.
One of the earliest population surveys of non-human primates was done in the country (Southwick and Siddiqui, 1966) which was mainly for the Rhesus Macaque in northern Indian states. Khajuria (1966) published a brief account of the distribution of Assamese Macaque in certain parts of Darjeeling district. Mukherjee and Mukherjee (1972) also conducted surveys for some of the same states and for the same species. Dolhinow and Lindburg (1980) surveyed the forest populations of Rhesus Macaque and Hanuman Langur in the same region. Kurup (1984) recorded the survey findings of Andhra Pradesh, Karnataka, Tamil Nadu and Kerala. Zoological Survey of India conducted survey of non-human primates from 1977 to 1981, particularly of the Rhesus Macaque and Hanuman Langur of India and recorded the distribution, abundance and present status of these two species in different states of India (Tiwari and Mukherjee, 1992). Field studies of non-human primates were also made by Mukherjee et al. (1995), Murmu et at. (2004) and reported the entire range of distribution of Rhesus and Assamese Macaque of Darjeeling district. Chaudhuri et. al. (2006)

METHODOLOGY
In order to do this, initially, contact was made with the forest officials to inquire about the availability of these primates. However, most of the staff and officers of the forest department and forest labourers were found to be keen observers of these primates. In addition to above, knowledgeable villagers were also contacted to have further information available, if any. On receipt of the information counting by direct count method of different troops living by roadsides and adjacent forests was adopted. Utmost care was taken to count them but as some of the groups were wild there might be some chances of missing a few members in some groups.
Driving a vehicle at slow speed (20-30 km per hour) made the roadside surveys with four observers keeping a constant watch for monkeys and langurs along the road and roadside forests.
In forest different ecological areas were selected for census and transect and point methods were applied to locate them. Surveys were conducted during dry periods only to obtain quite clear visibility to scan a long distance as far as clearly visible through a 7 x 50 binocular. At Takdah due to dense fog the visibility was too poor and it was not possible to make an extensive survey. Selected groups in each sub-division were observed to estimate population growth and birth rate.
The individuals of a group were classified as adult males, adult females, juveniles and infants.
Juveniles were identified as those, which were independent of their mothers. Infants were identified as those that were carried by their mothers.

ECOLOGY OF THE STUDY AREA
Darjeeling district lies in the northern part of West Bengal, extending between 26° 33' to 27° 13' N latitude and 88° 2' to 88° 56' E longitude with a geographical area of about 3148 sq. km. The major part of it lies in the eastern Himalayas ranging at an elevation between 200 m at Reang in the Teesta Valley to about 3800 m near Sandakphu and Phalut. The climate of the area also varies considerably due to altitudinal variations. The major crops of the area are rice, wheat, maize and tea. The area also experiences a few winter shower and snowfalls in many places during winter months. The main rivers are Teesta and Mahananda, which with their numerous affluence form the drainage system. Nearly 550 km. road was surveyed including forest road and foot trails and 46 groups of Macaca assalnensis, 27 groups of Macaca mulatta and 2 groups of Semnopithecus elltellus were seen in the forested habitat and roadsides (Fig. I).
The Darjeeling district has four sub-divisions. The Siliguri sub-division was devoid of Assamese Macaque and was replaced by Rhesus Macaque. The other three sub-divisions viz. Kurseong, Kalimpong and DarjeeIing were found to contain the entire population of Assamese Macaque. The distribution and social composition of Assamese Macaque is given in Table 1, of Rhesus Macaque in Table 2 and of Hanuman Langur in Table 3.    male to adult female was 1 : 2.9; adult female to infant was 1 : 0.5 and ratio of females to combined population of juvenile and infant was 1 : 0.9. Moreover, a third group was observed in the top canopy of the same area, which could not be counted due to poor visibility. Population composition and incidence of monkeys is detailed in Table 4.  It has been amply emphasized that human disturbance to habitat has important consequences on the demography, behaviour, and ultimately the survival of non-human primates, specially of the Indian subcontinent (Bishop et aI., 1981). During present investigation it was observed that, as the provisioning was highest at temples and tourist areas the population of Assamese Macaque has shown considerable increase in their population. On the other hand as the provIsIonIng was low in the forest areas the population of Rhesus Macaque did not show much increase.
It is evident from the present surveys that Rhesus Macaque population has increased considerably than that of Assamese Macaque at Darjeeling district. The Assamese Macaque was at present found inhabiting only at Darjeeling district in Bengal. The Rhesus Macaque is a highly adaptive species among the Macaques and now it is invading the territory of Assamese Macaque in the district. The Assamese Macaque is a broad-leaf, evergreen species but due to shrinkage of forest habitat and scarcity of preferred food this species is forced to harbour in the roadside forest predominantly of monoculture habitat at Darjeeling. If the Rhesus Macaque proceed on invading the higher elevation of Darjeeling district then there is a possibility of decline in Assamese Macaque popUlation. So, regular monitoring is needed to formulate a strategy for survival of Assanlese Macaque in this montane region of West Bengal. Hanuman Langur was found to live in top canopy to avoid territorial fight with other primate species.
For better conservation attention needed to be given on the following points : 1. Study of communicable diseases especially of Assamese Macaque.
2. Group wise capture, translocation and release in suitable habitats.
3. Systematic analysis of attitude of people towards monkeys.
4. Grow more trees in newly constructed housing colonies to provide food and shelter.
5. Continue density estimate to gather more information on population trends.

STATUS OF MALAYAN GIANT SQUIRREL
Within the Indian limit, the Malayan Giant Squirrel, Ratufa bicolor gigantea (M'Clelland) [Status IUCN L Rnt] is restricted to the mixed semi evergreen or evergreen forests of Northeast India. Ecological requirements of this squirrel are very different from most of the diurnal vertebrates. At present, rapid destruction of its habitat in northeast is adversely affecting their popUlation and no detailed information about the popUlation size of this taxon recurring in Indian range is available. However, for adopting an appropriate conservation programme, it is much necessary to have detail conservation programme. It is much necessary to have detail information of this species in respect of distribution, ecology, hebaviour, popUlation etc. Unfortunately, very little information is available about this significant species occurring in the North Bengal. This species can be used as an indicator species for making assessment of the quality of habitats. To fill up this lacunae this research project has been taken up by the Zoological Survey of India. In connection with this project, seasonal surveys were conducted in the different forests of Darjeeling district, North Bengal. Survey was done on foot by a four-member team along the jungle roads but occasional entry was also made deep inside the forest to locate the animal. Survey was conducted from early morning to noon and again from afternoon to evening.

DISCUSSION
Most of the sighting records were made during feeding. If not disturbed, it was found to feed on a single tree for more than 40 minutes. However, none of the animals were found to feed on the trees of the forest village. Chakraborty and Chakraborty (1991) reported on the activity pattern and population of this squirrel in Jalpaiguri district of North Bengal.  reported about the status of this squirrel in different forests of North Bengal. They also reported about their feeding habits.
During survey it was observed that their feeding activity continues almost throughout the day.
Feeding activity starts within an hour of sunrise and continues till dusk with a lean period fronl about 1.00 p.m. to 3.30 p.m. For feeding, it comes out of the dense forested part to somewhat open areas and is restricted to a selected tree species within as small area. In the morning activity is related to feeding and interspecific territorial chasing. During noon it takes rest lying flat on the shaded branches of tree. Wide varieties of foods are taken depending upon the availability within the foraging ground. It was also observed that the animal debarks the trees in search of insect food.
From the sighting frequency and number of animals sighted it appears that it lives in pairs or sometime singly. But at certain times even five to six animals were also found foraging in the same area. It was also found that different species of birds, Macaques and Langurs sharing the food items with this species at certain areas. Due to very nice matching colour with the back ground forests, this species can easily be located for its frequent characteristic loud call and dropping of leaves, fruits, seeds etc. The forests of Darjeeling district supports and carries a good population of this squirrel. Chakraborty and Chakraborty (199 I) reported that this squirrel is strictly arboreal and never descends below 5 metre. But during survey work a pair was found feeding on seeds on ground inside forest at Lava-Lolegaon road and a pair was found crossing the road running to reach the other side forest on the same road.