The increase in the number of tigers in the Western Ghats and the spillover of their population from Mudumalai and Sathyamangalam Tiger Reserves (MTR and STR) into the Nilgiris forest division are exposing them to higher chances of natural and unnatural causes of mortality, a recent investigation by the National Tiger Conservation Authority (NTCA) into the deaths of 10 tigers (four adults and six cubs) has said.
The deaths occurred between August 16 and September 19 at five locations — two within the MTR and three in the Nilgiris forest division. The NTCA, along with K. Ramesh, Scientist-F, Wildlife Institute of India, Dehradun; M. Kirupashankar, Regional Deputy Director, Wildlife Crime Control Bureau (WCCB); and Doki Adhimallaiah, Wildlife Inspector from Chennai; investigated the deaths.
In their report, the NTCA and the State Forest Department have said that the Western Ghats landscape, comprising the Nagarhole-Bandipur-Wayanad-Mudumalai-Sathyamangalam-BRT complex, has around 30% of India’s total tiger population. “Given the high and increasing number of tigers here — from 382 in 2010 to 828 in 2022 — the dispersal of the tiger population from high-density reserves to those with relatively less tiger occupancy would be natural phenomena,” the report said.
It has been noted that the MTR, which is contiguous with the Nilgiris forest division, is a high-density tiger habitat that has witnessed a significant increase in tiger population over the last decade. “The first choice of movement of tigers [from the MTR] would be the potentially suitable and less/unoccupied areas by other tigers to avoid potential conflict [with other tigers]. Therefore, the recent spurt in the number of tigers in the Nilgiris forest division, which is relatively less occupied by tiger [sic], is only on the expected line... and should be placed in the context of normal population dynamics of tigers,” the report said.
Since 2010, the tiger population in Mudumalai has increased by 123% — from 51 to 114 in 2022.
As the Nilgiris forest division is contiguous with both the MTR and the STR, their population is set to grow in the future. The tigers in the division are also venturing into areas that are moderately used by humans, which exposes them to a higher chance of natural and unnatural causes of mortality, the report noted.
Following the investigation into the death of the 10 tigers, the NTCA noted that the death of two cubs in the Segur forest range in the MTR was probably due to abandonment by their mother. Causes for abandonment include weak condition of at least one of the cubs, anthropogenic pressure, or the mother being inexperienced. In Chinna Coonoor, where four cubs died, officials had noted that as cubs grow older, their mother needs to make more kills to ensure her cubs’ survival. Lack of prey could have made their mother venture longer distances [in search of prey], which could have led to the cubs being left unattended and, eventually, their death.
“In both the cases, it is not clear who the mothers of the cubs are. This requires further investigation based on intensive camera trapping and DNA sampling from the entire region, which is a long-term measure,” the report added.
The deaths of two adult tigers in Naduvattam and Kargudi in the Nilgiris forest division and the MTR respectively are most likely caused by in-fighting, while the death of two other tigers near Avalanche “were a clear case of poisoning” in a “retaliatory killing” by an aggrieved person, the report noted.
“However, this needs to be taken with caution as this region has previous records of operation by poachers,” the report said, adding that a group of poachers from northern India are known to have settled in this landscape and “operate clandestinely with specific targets.”
The NTCA suggests increased monitoring of the tiger population in the landscape, establishing better networks of informants and investigating tiger sightings across human-dominated landscapes.
In the process of trying to identify the mother of the cubs that were found dead in Chinna Coonoor, camera traps managed to capture images of six tigers — three males, two female and one new tiger of an undetermined sex.
