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Tourism and human activity is stressing India’s tigers and even affecting choice of breeding sites, according to a worrying new study by the CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad.
A team of scientists from CCMB led by G Umapathy followed tigers in different parts of India through four seasons over two years to understand how human presence impacts tiger well-being.
In this study, in a marked departure from his previous ones, Umapathy and his team combined non-invasive stress and reproductive hormone analysis from tigers across five major Indian tiger reserves. These include:
Corbett (Uttarakhand)
Tadoba-Andhari (Maharashtra)
Kanha (Madhya Pradesh)
Bandhavgarh (Madhya Pradesh)
Periyar (Kerala)
The team analysed genetically confirmed 610 tiger scat samples, which include 291 females and 185 males, collected between 2020 and 2023. They checked for two key hormone markers in these samples, faecal glucocorticoid metabolites (a biomarker of stress) and faecal progesterone metabolites (an indicator of breeding activity in females), according to a statement by CCMB.
“Across all reserves, tigers ranging close to tourism roads and in areas with greater human disturbance consistently showed elevated stress hormone levels,” noted the statement.
A particularly striking finding is that tigers in the strictly protected core zones showed higher stress response to human-caused disturbance than those in the multi-use buffer zones.
Buffer-zone tigers appear to have habituated to year-round human presence, while core-zone tigers register sharp spikes in stress when seasonal tourism enters these areas. This challenges the assumption that core zones are uniformly low-stress refuges.
Of the five reserves, the effect was most pronounced in Tadoba and Bandhavgarh.
Worryingly, the impact of tourism and human presence is also being felt on the breeding habits of the big cats.
“Tigresses prefer breeding in the quiet parts of the forests. However, it is getting difficult to find such suitable areas. In Tadoba and Corbett, the buffer zones already have high tiger populations. It is concerning if the core areas of the forests also become stressful for the tigresses,” said Umapathy, Chief Scientist at CSIR-CCMB. “Not only the reproductive success of tigers is lower under stress, further the young ones will grow up differently in such conditions.”
“We are not arguing against wildlife tourism, which plays a vital role in conservation funding and supports rural livelihoods,” said Umapathy. “But our findings make a clear scientific case that the way tourism is regulated, vehicle numbers, safari timings, road density and the protection of breeding areas, needs to be informed by what the animals are actually telling us through their physiology.”
The study suggests key management recommendations which include strict regulation of tourist vehicle numbers and prevention of vehicle crowding at tiger sightings; reduction of safari duration by approximately one hour in both morning and evening sessions; strengthened management of buffer zones, particularly in Tadoba and Bandhavgarh against high anthropogenic disturbances; creation of additional water bodies along non-tourism routes to reduce dependence on roadside waterholes; continuous, non-invasive physiological monitoring of known tigresses to identify and protect breeding hotspots.
“We hope these findings will be useful to the National Tiger Conservation Authority and to state forest departments as they continue to fine-tune the management of India’s tiger reserves,” said Dr. Vinay Nandicoori, Director, CSIR–CCMB
The other authors who participated in this study include Aamer Shoel, Vinod Kumar, Anusha, and Ganswidt.
The study has been published in the Zoological Society of London journal Animal Conservation.
