Tourists take pictures of a tiger during a safari ride in a tiger reserve.
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Tigers that roam close to tourism roads or in areas with high human activity consistently show elevated stress hormone levels. More strikingly, scientists at the Hyderabad-based CSIR–Centre for Cellular and Molecular Biology (CCMB) have found that tigers living in strictly protected core zones exhibit a stronger stress response to human disturbance than those in multi-use buffer zones.
After tracking tigers across different parts of India over four seasons and two years, researchers set out to understand how human presence affects the well-being of animals. Their findings suggest that buffer-zone tigers may have habituated to constant human presence, while core-zone tigers experience sharp spikes in stress when seasonal tourism enters these areas.
This challenges the long-held assumption that core zones are uniformly low-stress refuges. The effect was most pronounced in Tadoba and Bandhavgarh tiger reserves, said chief scientist G. Umapathy. While previous studies by him had already established that tourism and other human activities can stress tigers, this study goes a step further by examining how such pressures influence reproduction.
CSIR-CCMB scientists as part of their study in forest areas.
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The research team analysed 610 genetically confirmed tiger scat samples—291 from females and 185 from males—collected between 2020 and 2023. They measured two key hormonal indicators: faecal glucocorticoid metabolites (a biomarker of stress) and faecal progesterone metabolites (an indicator of reproductive activity in females).
Across all reserves studied—Corbett (Uttarakhand), Tadoba–Andhari (Maharashtra), Kanha and Bandhavgarh (Madhya Pradesh), and Periyar (Kerala)—tigers found near tourism roads or in areas with higher human disturbance consistently showed elevated stress levels.
“Tigresses prefer to breed in quiet parts of the forest. However, it is becoming increasingly difficult to find such suitable areas,” said Dr. Umapathy. “In Tadoba and Corbett, buffer zones already hold high tiger populations. It is concerning if core areas also become stressful for breeding females. Not only is reproductive success lower under stress, but cubs may also develop differently in such conditions,” he said.
At the same time, the researchers emphasise that they are not arguing against wildlife tourism. “Tourism plays a vital role in conservation funding and supports rural livelihoods,” Dr. Umapathy noted. “However, there is a clear scientific case for regulating it—whether it is vehicle numbers, safari timings, road density, or the protection of breeding areas—based on what the animals are telling us through their physiology.”
The study outlines several key management recommendations such as stricter limits on tourist vehicle numbers and prevention of crowding at sightings, reducing safari duration by about an hour in both morning and evening sessions, stronger management of buffer zones, especially in Tadoba and Bandhavgarh, creation of water sources along non-tourism routes to reduce dependence on roadside waterholes, and continuous, non-invasive monitoring of tigresses to identify and safeguard breeding hotspots.
CSIR-CCMB scientists pursue tigers to check their stress levels in a tiger reserve.
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“This study is a fine example of how molecular biology and physiology can directly support one of India’s most important conservation priorities,” said CSIR-CCMB Director Dr. Vinay Nandicoori. “We take pride in housing the Laboratory for the Conservation of Endangered Species (LaCONES), which has become a national re will help the National Tiger Conservation Authority and State forest departments further refine the management of India’s tiger reserves,” he added.
Other researchers involved in the study include Aamer Shoel, Vinod Kumar, Gudimella Anusha and Andre Ganswindt. The research, published in the Zoological Society of London’s journal Animal Conservation, is the first to combine non-invasive stress and reproductive hormone analyses across five major tiger reserves in India.
(Funding and permissions: Supported by the Science and Engineering Research Board, Department of Science and Technology (CRG/2019/000348). Sample collection permissions were granted by the NTCA, MoEFCC, and the forest departments of Uttarakhand, Maharashtra, Madhya Pradesh and Kerala.)
Published – May 08, 2026 07:54 pm IST
