Study Finds Human Activity Is Affecting Tiger Breeding in India’s Reserves

HYDERABAD, India — Tourism and other human activity are increasing stress among tigers in several of India’s major tiger reserves and may be affecting their breeding, according to a new study by researchers at the CSIR-Centre for Cellular and Molecular Biology.

The study, published in the Zoological Society of London journal Animal Conservation, examined tigers across five reserves: Corbett in Uttarakhand, Tadoba-Andhari in Maharashtra, Kanha and Bandhavgarh in Madhya Pradesh, and Periyar in Kerala.

Researchers said the findings could help guide tiger management policies in individual reserves and support broader conservation planning.

The study was led by Dr. G. Umapathy of CSIR-CCMB, whose earlier work had found that tourism and other human activity in tiger reserves can cause stress in tigers. In the new study, the research team assessed how such activity may be linked to tiger breeding.

Scientists tracked tigers across different parts of India over four seasons during a two-year period, using non-invasive stress and reproductive hormone analyses. The team analyzed 610 genetically confirmed tiger scat samples collected between 2020 and 2023, including samples from 291 females and 185 males.

Researchers measured two hormone markers: fecal glucocorticoid metabolites, which indicate stress, and fecal progesterone metabolites, which indicate breeding activity in females.

Across all five reserves, tigers living near tourism roads or in areas with greater human disturbance had higher stress hormone levels. The study also found that tigers in strictly protected core zones showed stronger stress responses to human-caused disturbance than tigers in multi-use buffer zones.

Researchers said buffer-zone tigers appear to have become more accustomed to year-round human presence, while core-zone tigers showed sharp increases in stress when seasonal tourism entered those areas. The effect was especially noticeable in Tadoba and Bandhavgarh.

“Tigresses prefer to breed in the quiet parts of the forests. However, it is becoming 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,” Dr. Umapathy, chief scientist at CSIR-CCMB, said. “Not only is the reproductive success of tigers lower under stress, but the young ones will also grow up differently in such conditions.”

CSIR-CCMB Director Dr. Vinay Nandicoori said the study shows how molecular biology and physiology can be applied to conservation.

“This study is a fine example of how molecular biology and physiology can be applied directly to one of India’s most important conservation priorities,” Nandicoori said.

He said CSIR-CCMB’s Laboratory for the Conservation of Endangered Species has become a national resource for non-invasive wildlife monitoring and said the findings could help the National Tiger Conservation Authority and state forest departments refine reserve management.

“We hope these findings will be useful to the National Tiger Conservation Authority and state forest departments as they continue to fine-tune the management of India’s tiger reserves,” Nandicoori said.

Umapathy said the study is not an argument against wildlife tourism, which helps fund conservation and supports rural livelihoods. Instead, he said, tourism rules should reflect what tiger physiology shows about animal stress.

“We are not arguing against wildlife tourism, which plays a vital role in conservation funding and supports rural livelihoods,” Umapathy said. “But our findings make a clear scientific case that the regulation of tourism, including 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 recommends stricter regulation of tourist vehicle numbers, measures to prevent vehicle crowding at tiger sightings, shorter safari sessions, stronger buffer-zone management in Tadoba and Bandhavgarh, more water bodies along non-tourism routes, and continued non-invasive monitoring of known tigresses to identify and protect breeding areas.

Other authors of the study include Aamer Shoel, Vinod Kumar, Gudimella Anusha and Andre Ganswidt. (Source: IANS)