CHENNAI: The first-ever synchronised survey of the Nilgiri Tahr, conducted from April 29 to May 1 this year, has revealed a total population of 1,031 individuals in Tamil Nadu, with 552 living in fragmented habitats across 128 blocks and 479 in large contiguous landscapes spanning 12 blocks.
The survey report was released by State forest minister Ponmudi on Wednesday. This ambitious survey was part of Project Nilgiri Tahr, launched by Chief Minister MK Stalin in October last year, as a flagship initiative to conserve and study Tamil Nadu’s State Animal.
The survey results show if the population in the adjoining blocks in Kerala are taken into consideration, the combined population of Nilgiri Tahr stands at 1,858, with 1,229 individuals in Tamil Nadu and 827 in Kerala’s Eravikulam National Park. The three blocks of Grass Hills National Park - Kallar malai, Podhumalai and Kalugusuthimalai - share its boundary with two blocks of Eravikulam National Park (Kerala) - Vembanthani and Poovar. Similarly, with respect to the Nilgiri Tahr habitats in Mukurthi National Park, the Bangitapal block shares its boundary with Sispara of Silent Valley National Park in Kerala.
The Anamalai hills holds 41% of the total population of Nilgiri Tahr in Tamil Nadu, whereas Nilgiris landscape holds 24% of the population, which reflects the occurrence of meta population in two well-protected areas - Grass Hills National Park and Mukurthi National Park. The estimated Nilgiri Tahr population in Grass Hills National Park was 276 numbers in 20 groups, whereas 479 individuals occur in Grass Hills including the adjoining Kerala blocks of Vembanthanni and Poovar.
These findings illustrate that 197 Nilgiri Tahrs occur in the habitats located in the inter-state boundary between Tamil Nadu and Kerala in the Anamalais landscape. Similarly, the enumerated population of Nilgiri Tahr in Mukurthi National Park was 203 numbers in 24 groups. Moreover, 83 individuals occur common between both the states in Nilgiris landscapes (Bangitapal of Tamil Nadu and Sispara of Kerala), which use the habitats lying in the inter-state boundary.
The survey also highlighted the ecological dynamics of the population. The male-to-female ratio was estimated at 1:2, and the female-to-young ratio was 2:1, emphasising the species' reproductive potential. Nilgiri Tahr were observed at elevations ranging from 270 to 2,630 meters above sea level, and a new colonisation was discovered in the Pasumalai habitat in Chinnamanur Range. While, Tahr has become locally extinct in 8 historic habitats like Budha gundu (Pollachi), Nedungundru (Valaparai), Nadugani and Glenmorgan in Nilgiris, Mangaladevi and Spring of heaven in Megamalai, Panchangimottai (Kalakkad) and Pechimottai of Kanyakumari Forest Division. Nilgiri Tahrs were not documented in these habitats for the past few years.
Chief Wildlife Warden Rakesh Kumar Dogra told TNIE: "The survey results will serve as a baseline for conservation planning, help monitor population trends, neonatal and survival rates, predator-prey dynamics, and the impact of human activities. We will be conducting an annual survey during the same April-May period."
He said a deeper analysis was needed to understand why Tahr is moving into new habitats and not preferring some of the known historic landscapes. On radio-collaring, which was temporarily suspended following the death of a female Tahr recently, he said: "We were not moving away from radio-collaring, but repurposing. Radio-collaring will be done when we go for reintroduction of Tahr in new habitats."
Conducted across 13 Nilgiri Tahr-holding forest divisions in Tamil Nadu and adjoining areas of Kerala, the survey was the first of its kind and involved the collaboration of the Tamil Nadu and Kerala Forest departments, WWF-India, and IUCN. The survey spanned 1,862 kilometers of footwork, with drones documenting the process, and pellet samples collected for molecular studies at the Advanced Institute for Wildlife Conservation, Vandalur.