A resident population of tigers could be thriving in the high-altitude Shola forests in the Nilgiris forest division, rather than simply be using the landscape as a corridor to move between different traditional tiger habitats as was previously believed, argue researchers.
They recently published their findings on “Factors influencing survival of tiger and leopard in high-altitude ecosystem of the Nilgiris” in Zoology and Ecology (Acta Zoologica Lituanica).The researchers analysed 182 scat samples of tigers and leopards in the Nilgiris forest division, with molecular analysis showing that 67 samples belonged to tigers and 95 to leopards. The remaining samples could not be identified as belonging to either species.
Based on analysis of the scat of the two main carnivores in the Western Ghats, researchers observed that tigers and leopards both seemed to rely heavily on a diet of Sambar deer and wild boar. Tigers also had been recorded to have preyed on buffalo, black-naped hare, barking deer, gaur, spotted deer and mouse deer, though in much lesser proportion than when compared to their reliance on Sambar deer and gaur.
G. Mohan, one of the lead authors of the paper, told The Hindu that previously it was believed by researchers that tigers only used the Nilgiris forest division as a corridor to move between Mudumalai Tiger Reserve, Mukurthi National Park and Silent Valley in Kerala. “Recent evidence through camera traps indicates that this might no longer be the case, and that a breeding population of tigers could have become established in this division,” he said.
Camera traps placed in the Nilgiris division indicate that there may be around 34 tigers in the division, with another four tigers in the Mukurthi National Park.
R. Sanil, Associate Professor, Molecular Biodiversity Lab, Government Arts College (GAC) in Udhagamandalam, and another co-author of the paper, said that the overlap between tigers and leopards using patches of forest in the division is quite high, with leopards preferring to stray out of reserve forests into tea estates in search of prey.
“This could indicate competition from tigers in the Shola forests, forcing leopards out in search of food into tea estates, which in recent years has led to a number of deaths of leopards getting entangled in snares laid to trap wild herbivores” he said. Mr. Sanil also added that the photographic record of a pair of leucistic tigers in the division could point to a population that is in-breeding.
B. Ramakrishnan, assistant professor at the Department of Zoology and Wildlife Biology at the GAC in Udhagamandalam, said the study pointed to a healthy tiger population in the upper Nilgiris, necessitating more research and understanding to ensure their long-term protection.
“We must identify the corridors being used by tigers to move between habitats and ensure there is contiguity so that different populations mix and breed, while in the long-term, the government could consider announcing the Nilgiris division as a high-altitude tiger reserve,” he said. J. Yogesh, T.T. Shameer, Nittu George and J.B. Sulekha are the other co-authors of the paper.