DH Exclusive | Reclusive lion-tailed macaques in Western Ghats are becoming dependent on human food

There are only 3,500 of the elusive lion-tailed macaques (LTM) in the wild, all living within the Western Ghats. The reclusive creatures are not used to humans. Now, a study has found that the increased human presence in their area is prompting a dramatic change in the behaviour of the species.

Ashni Dhawale of the National Institute of Advanced Studies (NIAS) in Bengaluru, who, with other researchers, has been studying 170 individual macaques in Valparai, Tamil Nadu, has found that the species has become increasingly reliant on human food for survival.

“We are seeing less foraging of natural plant foods, such as fruits, pods, lichens and others, and more scavenging with human areas where the animals are primarily sourcing their food by raiding human habitations and garbage dumps,” Dhawale, a PhD student, explained.

At the same time, competition over human-sourced food is triggering more aggression. “Social binds are devolving. Allogrooming (where animals groom each other), which is important for establishing social links, is becoming diluted,” she added.

Scientists expressed concern that this behaviour change could further endanger the macaques, whose habitats are already under threat. In Karnataka, the 2,000 MW Sharavathi Pumped Storage Project falls in an area where 32 groups of macaques live and breed and has raised concerns that several groups will be wiped out.

The study, which was published on Wednesday, saw researchers focus on one of four troops in the Puthuthottam forest, a 92-hectare fragment of rainforest in the Annamalai range, which has been cut off due to extensive logging since the turn of the century.

The study found that the animals were spending about 41 per cent of their time in the forest interior and 21 per cent of their time on the first edge, where food discharged by tourists could be found. The animals further spent 29 per cent of the time raiding or lingering within human settlements.

“In the duration of the study, only one troop of 92 primates was found to be engaging in human food acquisition. However, since then, the remaining three troops have also joined in,” Dhawale said.

Dr Mewa Singh of the University of Mysore has studied the LTMs for over 30 years but was not involved in the new paper. He described the results as astonishing. “Twenty-five years ago, even if you kept bananas in the vicinity of a troop of LTMs, they would not touch it,” he said.

He said that the change showed that the species was remarkably adaptive. “A few years ago, I thought that the increased fragmentation and degradation of their habitat would lead to their abrupt extinction. But they are adapting to habitat alteration,” he said.

However, both Singh and the researchers added that further fragmentation of habitats and dissolution of social bonds within the macaque troops could lead to the extinction of the species.