Tourism and human activity are stressing India’s tigers, affecting choice of breeding sites: CSIR-CCMB study

A multi-year study by scientists from CSIR-CCMB (Centre for Cellular and Molecular Biology, Hyderabad) published in the journal *Animal Conservation* (Zoolog...

What Happened

A multi-year study by scientists from CSIR-CCMB (Centre for Cellular and Molecular Biology, Hyderabad) published in the journal Animal Conservation (Zoological Society of London) has found that tourism-related and general human disturbance consistently elevates physiological stress in tigers across five major Indian tiger reserves, and is compressing the availability of quiet breeding habitat for tigresses.
The research team analysed 610 genetically confirmed tiger scat samples (291 female, 185 male) collected across four seasons from 2020–2023 in Corbett (Uttarakhand), Tadoba-Andhari (Maharashtra), Kanha and Bandhavgarh (Madhya Pradesh), and Periyar (Kerala).
Stress was measured via faecal glucocorticoid metabolites (FGM — a validated non-invasive stress biomarker); breeding activity in females was assessed via faecal progesterone metabolites (FPM).
Tigers in areas closer to tourism roads and human activity zones showed elevated FGM across all five reserves; tigresses are finding it increasingly difficult to locate undisturbed breeding sites, with stress responses paradoxically higher in core zones than buffer zones in some reserves.
The study recommends strict caps on tourist vehicle numbers, reducing safari duration by ~1 hour, creating non-tourism water sources, and continuous physiological monitoring of breeding females.

Static Topic Bridges

Project Tiger and India's Tiger Reserve Framework

Project Tiger was launched in 1973 under the Wildlife (Protection) Act, 1972, making India the first country to undertake a state-sponsored, science-driven programme for tiger conservation at scale. It is administered by the National Tiger Conservation Authority (NTCA), a statutory body under the Ministry of Environment, Forest and Climate Change (MoEFCC), created under the Wildlife Protection Amendment Act of 2006. India currently has 58 designated tiger reserves (as of 2025–26).

Every tiger reserve is mandated to have a core zone (legally equivalent to a national park or sanctuary — inviolate, no extraction, minimal human presence) and a buffer zone (managed multiple-use area where regulated human activities including limited tourism are permitted).
The core–buffer structure is codified in Section 38V of the Wildlife (Protection) Act, 1972, which defines "critical tiger habitat" as areas required to be kept "inviolate for the purposes of tiger conservation."
India's wild tiger population has grown from ~1,411 (2006) to ~3,682 (2022 census) — a conservation success story; however, this recovery makes the discovery of stress-linked breeding disruption more alarming, not less.
Tiger reserves in the study: Corbett (India's oldest, est. 1936 as Hailey NP; home to the highest tiger density), Tadoba-Andhari (Maharashtra's largest), Kanha and Bandhavgarh (MP — the "Tiger State"), Periyar (Kerala — a biodiversity hotspot).

Connection to this news: The CCMB study reveals that even within the legally protected core zones — which are designed precisely to be inviolate — tourism-generated disturbance is measurably altering tiger physiology and behaviour. This directly challenges the assumption that core zone designation alone guarantees effective protection.

Non-Invasive Wildlife Monitoring and Conservation Genomics

Non-invasive monitoring refers to the collection and analysis of biological samples (scat, hair, shed skin, urine, environmental DNA) without physically handling or tranquillising the animal. For large carnivores like tigers, scat-based hormonal and genetic analysis allows researchers to identify individuals, assess health, reproductive status, and stress levels without any disturbance to the animal — a critical advantage given that captures themselves cause significant stress.

Faecal glucocorticoid metabolites (FGM): Glucocorticoids (primarily cortisol) are released by the adrenal gland in response to stressors (predation, competition, human disturbance). In scat, their metabolites persist for hours to days; elevated FGM indicates chronic or acute stress. Chronic glucocorticoid elevation suppresses immune function, impairs reproduction, and reduces survival.
Faecal progesterone metabolites (FPM): Progesterone is the primary female reproductive hormone; its presence in scat indicates luteal phase activity (post-ovulation) and pregnancy — a direct indicator of active breeding.
Genetic confirmation: Each of the 610 samples in the study was genetically confirmed to belong to a specific individual tiger using microsatellite or SNP-based genotyping from scat DNA, preventing duplicate counting — a methodological rigour that strengthens the study's conclusions.
CSIR-CCMB has been a pioneer in applying molecular genetics to wildlife conservation in India; earlier work from the lab contributed to tiger population censuses and lineage mapping across Indian reserves.

Connection to this news: The study's methodological strength — 610 samples, genetic confirmation, four seasons, five reserves, two hormone markers — makes it the most comprehensive physiological dataset on Indian tigers ever published, lending its policy recommendations significant scientific weight.

Wildlife Tourism Regulation in India

Wildlife tourism in Indian protected areas is regulated under the Wildlife (Protection) Act, 1972 and guidelines issued by the NTCA and state forest departments. The 2012 Supreme Court interim order temporarily banned tourism in core zones of tiger reserves; the ban was later vacated, with tourism permitted in designated tourism zones within the core. NTCA guidelines cap vehicle numbers per zone per day, mandate electric vehicles within cores, and prescribe speed limits, route restrictions, and buffer-zone hotel density norms.

Safari zones within tiger reserve cores are legally distinct from the inviolate core; however, the CCMB study's finding that even core-adjacent tourism roads elevate stress argues that the current spatial demarcation of tourism zones may be insufficient.
Buffer zones, counterintuitively, showed lower stress in some tigers — because tigers there have habituated to year-round human presence, while seasonal tourism influx in cores creates unpredictable disturbance.
Tadoba-Andhari and Bandhavgarh showed the most severe stress and breeding disruption — both are among India's most tourism-dense reserves with high visitor footfall.
The study's recommendation for continuous physiological monitoring aligns with NTCA's evolving adaptive management framework, which increasingly uses evidence-based triggers for management interventions.

Connection to this news: The study provides the first physiological evidence base for revising tourism carrying capacity norms — moving the debate from anecdotal observations to measurable hormonal data. This is exactly the kind of science that informs NTCA's periodic tiger reserve management plan revisions.

Key Facts & Data

Study institution: CSIR-CCMB (Centre for Cellular and Molecular Biology), Hyderabad; led by Dr G. Umapathy
Published in: Animal Conservation (journal of the Zoological Society of London)
Samples analysed: 610 genetically confirmed tiger scat samples (291 female, 185 male)
Collection period: 2020–2023 (four seasons)
Reserves studied: Corbett (Uttarakhand), Tadoba-Andhari (Maharashtra), Kanha and Bandhavgarh (Madhya Pradesh), Periyar (Kerala)
Stress biomarker: Faecal glucocorticoid metabolites (FGM) — elevated near tourism roads in all 5 reserves
Breeding biomarker: Faecal progesterone metabolites (FPM) — reduced in disturbed zones
Unexpected finding: Core zone tigers showed higher stress than buffer zone tigers in some reserves (habituation effect in buffers)
Worst affected reserves: Tadoba-Andhari and Bandhavgarh
Key recommendations: Cap tourist vehicles; reduce safari duration by ~1 hour; strengthen buffer management; create non-tourism water sources; implement continuous monitoring of breeding females
India's tiger population (2022 census): ~3,682 — world's largest
Number of tiger reserves (2025–26): 58
Legal framework: Wildlife (Protection) Act, 1972 (Section 38V — critical tiger habitat); Project Tiger (1973); NTCA (2006)