After launching Project Nilgiri Tahr last year for the conservation of the State animal, Tamil Nadu is now working on a standardised protocol to count the endangered population of southern India’s only mountain ungulate. The Tamil Nadu Forest Department will also propose to its Kerala counterpart to conduct a synchronised census, as the animal is only found in select habitats in the two States.
For the first time, drones may be incorporated in the census, as the Nilgiri tahr prefers montane grasslands, with steep and rocky terrains at an altitude between 300 and 2,600 metres above sea level. There are believed to be a little over 3,100 of the animals living in highly fragmented habitats in the Western Ghats in Tamil Nadu and Kerala, ranging between the Nilgiris in the north and the Kanniyakumari hills in the south, according to a 2015 study by WWF-India.
Synchronised survey
The Tamil Nadu Forest Department is proposing two censuses: one in November, after the southwest monsoon, and the other in March or April, after the calving season. If Kerala agrees to the proposal, the second census is likely to be a synchronised count, while the post-monsoon monsoon exercise in November will be carried out in tahr habitats in Tamil Nadu alone.
Supriya Sahu, Additional Chief Secretary of the State’s Environment, Climate Change and Forest Department, said that this would be the first comprehensive, exclusive census for the State animal. Modern technologies will be adopted to carry out the exercise in difficult terrain, and the Department will seek technical support from institutions such as the Wildlife Institute of India (WII).
“Experts, with whom the Department had a consultation, have opined a synchronised survey is the need of the hour,” said Ms. Sahu, who took the lead in launching Project Nilgiri Tahr.
Counting techniques
Senior forest officials and biologists from the two States, and the research team from Project Nilgiri Tahr recently held discussions with experts from WWF-India, the Nature Conservation Foundation, and the WII to formulate a scientific and accurate technique of population enumeration. Experts felt that bounded count and double-observer survey methods could be priority models. Camera traps could also be used in difficult terrains.
“The focus was to adopt a refined model from different methods that provide high accuracy and less variability in results,” said M.A. Predit, coordinator for WWF-India’s Nilgiri tahr conservation programme.
This November, Tamil Nadu is hoping to count the tahrs living in various habitats, including the Nilgiris hills; Siruvani hills; Anamalais, high ranges and Palani hills; Srivillipudur, Theni and Tirunelveli hills; and the Kalakad Mundanthurai Tiger Reserve and Ashambu hills. Among these, the Anamalai hills and the Nilgiris, mainly the Mukurthi National Park, are home to the highest number of the animals.
Tahrs unfazed by drones
The experts felt that Tamil Nadu can conduct an annual census each November, as well as an additional biennial synchronised census with Kerala, after the calving season.
“The Project Nilgiri Tahr team, during field visits, experimented with drones to observe tahr groups. Contrary to our perception, they were not disturbed by the drone flown around 100 metres above them,” said S. Ramasubramanian, Conservator of Forests and Field Director of the Anamalai Tiger Reserve, which is the second biggest habitat of the animal after the Eravikulam National Park in Kerala.
Habitat threat
Officials hope that the exercise will help the Project Nilgiri Tahr team to understand the dynamics of population density of the ungulate spread across the different landscapes, and its range of habitats.
Besides anthropogenic pressures, Nilgiri tahr habitats face threats in the form of the spread of invasive plants such as wattles, pines, and eucalyptus in the grasslands. A component of the Project Nilgiri Tahrs aims to study the possible causes of the lumpy skin disease that has been observed in the animal, and suggest a remedy for it.
