Surveying tigers: A big challenge in Manipur

Rahul Ashem *

A Tiger Cub at Guwahati zoo, Assam in October 2013 :: Pix - Cavendish Maibam

Tigers mostly prey on hoofed animals, either wild or livestock. The presence of tigers depends on their hunting skills. Sometimes, tigers pose serious danger, for the same space and resources with the human population. Manipur is located in the north of Nagaland, west of Assam, south west of Mizoram, and east of the country, Myanmar. The neighbouring states and country record the presence of tiger habitats. Meghalaya and Tripura also have reports of occasional tiger occurrence.

The genus tiger needs sound environment with varied small to medium sized mammals’ population and dense canopy covered for better prospects of food habit, feeding, mating season, rearing, refusing and dispersal. In fact, tiger needs inviolate space with no human interference. The Forest Survey of India, 2017, reports the net increase of 263 sq km forest covers in Manipur which is a good sign of regenerating the forests.

The districts, Tamenglong, Senapati, Ukhrul and Chandel marked the beginning of a new conservation era and plantation activities as well as re-growth of shifting cultivation areas. The report shows that the State forest cover includes the dense (908 sq km), moderate (6510 sq km) and open forests (9928 sq km) respectively. The decrease of dense forests is mainly due to forest fragmentation, degradation, deforestation and forest conversion at present situation.

Most of the dense forests are distributed in the hills district of Tamenglong (390 sq km), Senapati (272 sq km), Ukhrul (193 sq km), Churachandpur (42 sq km) and Chandel (11 sq km). Studies reveal that the presence of tiger depends on the quantity and quality of available habitat. Manipur has varied ecological and anthropogenic features of forest cover, terrain, natural prey availability, presence of undisturbed habitat and the quality of managerial efforts.

It is also reported that tigers in moderate and open forests are more vulnerable to being hunted or killed. More importantly, tiger shifts their activity in response to human interferences in areas where there occur conflicts with human existence. In general, big cats tend to synchronize foraging with their prey and adapt temporal hunting patterns to the times when their prey is most vulnerable. Wildlife Institute of India (WII), Dehradun declared the big feline as extinct species from their records in the 2001 census.

A number of recommendations have been made for the occurrence of tigers from time to time but systematic understanding of population structure has not been documented so far. In the past few years though, scrapes, rake marks or sightings by local people have been reported from different districts of the State, but these are rare and occasional incidents.

However, presence of prey species and cattle being killed near the surrounding village was quite frequently recorded by Forest Department. The recent discovery of livestock killed in Sangkhumei village (Senapati district) is a symbol of the lack of well being of the ecological system. The cattle killed in Khordak Mayai Leikai (Bishnupur district) are another proof of the presence of the feline’s family in the State. An issue of tiger killed in Manipur-Nagaland border is a paradigm of occasional occurrence of the yellow-striped big cat in Manipur.

Therefore, taking stock of what we have and where the occurrences are, can be the first step towards conservation management. Monitoring tiger population is equivalent to monitoring the health of the ecosystems, which the tigers inhabit. The right step towards effective management and formulation of policy is to gain an understanding of where the tigers are and how many are there. Once the policy is formulated and implemented through field management, we then need to know whether it has the desired effect or not, i.e. of conserving the tigers.

This is the role of monitoring; so that results can permit mid-course corrections, if necessary, in management of actions and policy. The monitoring system for tigers, co-predators, prey and their habitat transcends beyond estimating mere numbers. In a holistic approach, the tiger can be used as an umbrella species to monitor some of the major components of forest systems in Manipur where the tiger occurs.

The data and inferences generated by the system not only serve as a monitoring tool but also as an information base for decision making for land use planning. It provides an opportunity to incorporate conservation objectives supported with a sound database, on equal footing with economic, sociological, and other values in policy and decision making for the benefit of the society. Besides, the need of time is to identify forest corridors that allow movement of tigers across district landscapes as tigers move long distances. The district, Senapati, has close borders with Nagaland, Tamenglong with Assam and Nagaland, Churachandpur with Mizoram and Ukhrul with the neighbouring country, Myanmar.

Moreover, Manipur is a transition zone between the Indian, Indo-Malayan and Indo-Chinese biogeographical regions as well as a meeting place of the Himalayan Mountain and peninsular India. Assam (Kaziranga, Manas, Nameri), which lies in the central part of north eastern states support the highest number of tiger densities in the world. The landscape commences in the North West from Arunachal Pradesh (Pakke tiger reserve) to the forests of Palia, tale valley, Mouling and up to Arunachal Pradesh (Namdapha tiger reserve) in the east.

The landscape continues south through some degraded areas into Nagaland (Intanki National Park) and further south to Mizoram (Dampa tiger reserve). Kaziranga National Park (Assam) in the Brahmaputra flood plains is connected through the Karbi Anglong hills to Intanki in the south.

This connectivity through Karbi Anglong is crucial for dispersal of tigers from their source population in Kaziranga. Intanki national park is also connected westwards through priority forests up to Balphrakram National Park (Meghalaya). The landscape has contiguous forest across the international border with Myanmar.

Method like pugmark counting, scat examination and camera trapping are common for tiger estimation. For best result, Geographical Information System (GIS) is used for total occupancy of tigers. Basically, tigers are known by its unique black stripe. The stripe is different from one another which make it easy in differentiating the tiger species from each other. The differentiation can be done with the help of naked eye, possibly for two to three species of tigers; however, identifying maximum number of tigers will be difficult.

This is the reason camera trapping is used, for capturing images of each individual tiger’s presence. The basic principle of camera trapping is based on the individual specific stripe patterns. It also helps in identifying each individual species of tiger with their stripe pattern on flanks, limbs, tails and forequarters and separates male from female, cub or unidentified individuals.

Before the trapping session, study areas have to be extensively searched by conducting sign surveys to find the ideal location within each grid for camera deployment so as to maximize the chances of photo capturing a tiger. Cameras are usually operated between 40 to 60 days each site with an effort of over 500 trap nights per 100 sq kms. The capture data can be analyzed using closed population models and spatially explicit likelihood based approaches. However, camera trapping works best in areas where tigers are in high or moderate density.

The technique is used only in a few predetermined locations where camera traps are set and cannot be used in difficult hilly terrains. At present Moultrie, Trailmaster or Reconyx camera is used for density estimation of tigers. It is not possible to install cameras at every place that is likely to have tigers, and even in places where they are installed, there is no certainty that the tiger would walk into a camera’s range. Some tiger population could not be assessed by camera trapping capture mark recapture due to logistic constraints like insurgency or extremely low density.

In such areas, they need to use non-invasive techniques like pugmark and scat analysis methods to estimate the minimum number of individual’s species. Pugmark method is another technique in counting tiger numbers. Each and every tiger is known to leave a distinct pugmark on the ground and these are different from others in the big cat family. The identified pugmark can further be classified into old, fresh and very fresh in accordance with the presence of pugmark in that particular environment for better analysis of tiger existence.

In this case, the term stride and straddle is applied, where measurement of animal walk in a normal gait is studied to distinguish the pugmark from other big predators like leopard, wild dogs or even clouded leopard. Stride is the distance between two successive pugmarks on the same side while straddle is the perpendicular distance between the left and right hind pugmarks.

The pugmark is clearly photographed in a serial way by; take the GPS (Global Positioning System) locations for statistical analysis. In most of the cases, Adult male tiger pugmark (MTP) forms a square while female tiger pugmark (FTP) fits into a rectangle shape. Toes in male are rounded whereas it is fairly elongated in females. Female pugmark length and breadth is 1.5 cm more than male tiger pugmark. The interesting fact is, tiger cub pugmark (TCP) is quite similar with the leopard or wild dogs’ pugmark. The difference in wild dogs is summed up as non visible claws; toes are smaller and pads larger in tiger (visible claws, toes larger and pads smaller in dogs).

Sometimes, Pugmark Impression Pads (PIPs) are made where animal frequently walks (roads, trails), for getting the clear mark of pugmarks. PIPs consists of an area approximately 6m long and as wide as the road ( nearly 2.5 m) where the soil is finely pulverized to an optimal soil depth of 0.5- 1 cm in order to provide the best possible surface for recording pugmark impressions. Moreover, pugmark method is helpful in tracking other strayed animals from the boundary areas, conflicting with the human environment or creating problems of their own because of injury.

The last possible method for identifying the presence or absence of tiger habitat is through non invasive methods of collection or simply scat analysis which is done after collecting scats from the field. There are two (2) possible ways of scat preservation, one with help of desiccant silica gel pouches containing 50 ml screw cap tubes and other dipping in 70-90 % ethanol. Drying of scat is necessary when the scat found is very fresh. In fact, scats can be classified as old (dry with hair and bone visible), fresh (dry but intact with shiny surface) or very fresh (soft, moist and smelly); scent mark (spray, rolling) or rake on trunk, scrapes on ground or even kills prey (predation on wild prey).

It is difficult to use camera trapping technology in the hills district of Manipur. Pugmarks techniques and scat analysis are more accurate and easy methods to identify the presence of large feline in the hill district like Tamenglong, Senapati, Ukhrul and Churachandpur. Simple protocols should be developed to collect data on carnivore sign survey encounters, tiger prey encounters, indices of human disturbances, indices of habitat status and dung counts on plots.

Working with the government and local communities to improve protection are other strategies for the conservation of the landscape. At a broader level, framework based ecosystem valuation must be developed to assess the impacts of linear infrastructure on ecosystem. Biodiversity conservation remains a big challenge for all.