Lion-tailed macaques form large groups outside protected areas in Valparai plateau

Long-term monitoring of the endangered lion-tailed macaque (LTM) in the Valparai plateau has found the shy primate of the rainforests forming unusually large groups in non-protected areas, according to a recently published study.

One of the five groups of LTMs at Puthuthottam, which is located within private plantation areas near Valparai town, was found to have 117 individuals, whereas the mean group size of the primate across protected areas in the Western Ghats is less than 20. A second group at Puthuthottam had 51 LTMs. Another population in a private estate at Korangumudi was found to have 78 individuals.

Puthuthottam, Pannimedu, Korangumudi and Tata Coffee were the private plantation areas (non-protected areas) that were among the 10 fragmented areas surveyed for the study. As many as 34 individuals recorded in a group at Panathiar-1 was the highest among the groups in protected areas surveyed as per the study: Differential demographic responses of lion-tailed macaques to habitat fragmentation: Four decades of population monitoring in the Anamalai Hills, Western Ghats and perspectives for management and conservation.

The total population of LTMs in the Valparai plateau, which falls under the Anamalai Tiger Reserve (ATR), was estimated to be around 800 in 37 groups as per the study that was conducted between February 2021 and August 2024. Out of the 37 groups recorded across the 10 rainforest fragments, five were in Puthuthottam and one each in Tata Coffee, Korangumudi and Pannimedu. The remaining 29 groups were recorded in the fragments within protected areas such as the Varagaliyar complex, Iyerpadi – Akkamalai complex, Andiparai Shola, Hindustan Shola, Sankaranakudi Shola and Waterfall Shola.

As per long-term monitoring data, a single group of 17 individuals was recorded at Puthuthottam in 1984, which got split into two groups of 40 individuals by 1994. The two groups remained till 2010 with 122 individuals before splitting into four groups by 2015. The population size increased to nearly 200 by 2020 and to 225 individuals in five groups by 2024. The group of 19 LTMs recorded at Korangumudi in 1990 increased to 83 by 2021. Though the groups in TATA Coffee and Pannimedu remained around 15 and seven respectively for several decades, the two groups showed an increase in the group size to 21 and 15 by 2024.

According to Honnavalli N. Kumara, Principal Scientist at the Salim Ali Centre for Ornithology and Natural History and one of the authors of the study, the population of LTMs in all protected areas was relatively stable while steady growth was observed in private fragments like Puthuthottam and Korangumudi.

“Now one group from Puthuthottam is frequenting Valparai town and another group spending a lot of time at Rottikadai. People are also seen feeding LTMs in places like Iyerpadi. If left unaddressed, LTMs will get used to this type of feeding and they might move more into human inhabited areas, affecting their behaviour and population dynamics,” he warns.

Though factors behind the exponential population growth in Puthuthottam remain unknown, consumption of human food items, availability of cultivated fruits and adaptation to human presence and provisioning could be among the reasons, as per the study, co-authored by Santanu Mahato, G. Umapathy, Mridula Singh and Mewa Singh.