India’s sixth national tiger count has already produced more than 50 million camera-trap images for about 150 researchers to sort, The Tribune reported on July 29, and environment ministry officials expect the result to show a further rise of 10 to 15 percent.
Every count since 2006 has gone up. The official average climbed from 1,411 tigers that year to 3,682 in 2022, which the Wildlife Institute of India, the government body that runs the analysis, describes as growth of 6.1 percent a year. Scientists who have spent two decades challenging the method say the population on paper is once again rising faster than the animals can, as it did when forest guards counted footprints, according to an essay in Alter published Friday. They want the raw data released.
The record backs a narrower claim than the headline figures. The firmest part of the census is the tigers actually photographed: 3,080 individuals older than a year in 2022, up from 2,461 in 2018. That 25.1 percent rise came as camera locations increased 21.4 percent and foot surveys 22.6 percent, so part of the gain may reflect more searching rather than more tigers. About one tiger in six in the national figure comes from a model that carries camera-trap densities into forest no camera watched. And because the raw data from the counts has not been released, no one outside the government can test either side’s case.
Almost no one in the dispute denies that India’s tigers are recovering. The argument is over how fast, and how anyone could know.
How the number is made
The count starts on foot. Since 2006 a forest guard and an assistant have walked every beat, a patch of about 15 to 16 square kilometers, over eight to 10 days, recording carnivore sign, prey seen along line transects, vegetation, dung and human disturbance. In 2022 those walks added up to 641,449 kilometers across 10,146 grid cells of 100 square kilometers each, according to the government’s summary report. Satellite layers of forest cover, terrain, roads, night lights and the human footprint are matched to the same grid.
Then come the cameras. Pairs go in at a density of at least one location per two square kilometers, at knee height and angled to catch both flanks, and stay out for roughly 25 to 45 days, Scroll reported. In 2022 they ran at 32,588 locations on 174 sites and took 47,081,881 photographs, 97,399 of them of tigers. The full 494-page report gives a slightly different count of 32,803 locations on 175 sites. Software called CaTRAT sorts the frames by species, a second program matches stripe patterns, and biologists check the matches by hand.
Statistics do the rest. Spatially explicit capture-recapture, the main method since 2014, uses where each camera sat, which tiger it caught and when to estimate density, including the animals no camera caught. Inside the camera-trapped areas that produced 3,167 tigers, which the report calls the country’s minimum. For forest where the foot crews found tiger sign but no cameras were set, the model predicts density from sign encounter rates, prey, dung and the satellite layers, “based on joint distribution of covariates,” the summary report says. Adding that modeled space gave the average of 3,682, with a standard error of 243 and an upper limit of 3,925, according to the government’s release on July 29, 2023.
Dr. Qamar Qureshi, a Wildlife Institute scientist and lead editor of the report, described the split to Down To Earth in August 2023. “We thus have data for 83 per cent of the tiger population,” he said. “The rest is extrapolated.” The 3,080 photographed tigers make up 84 percent of 3,682.
Footprints and a fabrication
The first national count, in 1972, rested on a pane of glass. S.R. Choudhury, an Odisha forester who had run a state census in 1966, built a “tiger tracer,” a framed 6-by-8-inch glass plate on adjustable legs for tracing pugmarks, and trained officers for 18 days that March and April, Alter recounts. His method assumed that every tiger’s print was distinct and that every tiger kept to its own territory. The count came to 1,863, by Alter’s figures. Mr. Choudhury considered camera photography and rejected it for a national census because it would cost too much.
The doubts came early. S. Dillon Ripley of the Smithsonian called the method subjective and unverifiable. In 1987 Dr. K. Ullas Karanth, now emeritus director of the Centre for Wildlife Studies, gave six census experts 33 tracings taken from four tigers. Their counts ranged from six tigers to 24. Radio-collar studies in Nepal and India later showed that tiger ranges overlap heavily and that transient animals wander widely. That broke the method’s other assumption.
In a 2003 paper in Animal Conservation, Dr. Karanth and eight co-authors, among them the conservationist Valmik Thapar, wrote that the pugmark census “targets, but fails to achieve” the hardest goal, an absolute count, while ignoring the simpler work of mapping where tigers live. The 2001-02 census, the last done by footprint, reported 3,642 tigers.
Then Sariska emptied. Census reports had credited the Rajasthan reserve with 24 to 26 tigers from 1993 to 2003 even as staff sightings fell to zero by 2002, Alter reported, and the 2004 figure was still 16 to 18. Visitors had not seen a tiger in months. The Central Bureau of Investigation found that poachers had killed them. Prime Minister Manmohan Singh appointed a task force chaired by Sunita Narain of the Centre for Science and Environment, and its report, Joining the Dots, was delivered on Aug. 5, 2005. It found “tigers in books, not on ground,” [according to the center’s summary of the findings](https://cdn.cseindia.org/userfiles/TTF%20Presentation(1).pdf), and recommended scrapping the pugmark count.
The new method’s first national result, released in 2008, was 1,411. Dr. Yadvendradev Jhala, the Wildlife Institute scientist who led it, was blunt when early numbers came in. “Earlier censuses used pugmark spottings to determine tiger population, which is considered unscientific,” he told Down To Earth in June 2007. “Also, data was systematically fabricated to show an increasing trend in population.” Madhya Pradesh, which the old census credited with 700 tigers, turned out to have 265.
Dr. Karanth reads the drop another way. In a 2023 essay for Down To Earth, he wrote that officials “cleverly ‘reset’ the base tiger numbers from 3,600 in 2002 to an improbable low of 1,400 in 2006,” setting up the success stories that followed.
Sariska itself was restocked with tigers from Ranthambore beginning in 2008. Its count reached 50 last year, ThePrint reported, and 58 this month, more than half of them cubs, according to The Free Press Journal.
From 1,411 to 3,682
The official series runs 1,411 in 2006, 1,706 in 2010, 2,226 in 2014, 2,967 in 2018 and 3,682 in 2022. The 2018 round, with cameras at 26,838 locations on 141 sites, entered Guinness World Records as the largest camera-trap wildlife survey, The Tribune reported. Its range was 2,603 to 3,346.
Prime Minister Narendra Modi announced the 2018 result on July 29, 2019, International Tiger Day, as a pledge kept early. Tiger-range countries had set 2022 as the target year for doubling wild tiger numbers.
A commitment fulfilled, that too well in advance!
It was decided to work towards doubling the tiger population by 2022 but India achieved this 4 years in advance!
India is proud to be home to almost 75% of the global tiger population. #InternationalTigerDay
Two months later The Indian Express examined the photographs behind the 2014 report and found that about one tiger in seven could be a “paper tiger,” the same animal counted twice or three times. Experts working with the paper said 221 photos should have been thrown out and the count was too high by as much as 16 percent, The Wire reported. The Express also wrote that the population was “undoubtedly on the rebound.”
A Nature editorial on Oct. 30, 2019, said the government “must trust independent scientists with the raw data.” In January 2020 the National Tiger Conservation Authority, the ministry body that commissions the count, wrote to the Wildlife Institute proposing to restructure its tiger cell to “bring more accountability, transparency and scientific robustness,” the Express reported, as Phys.org summarized.
The 2022 round brought a fresh mix-up. On April 9, 2023, at an event in Mysuru marking 50 years of Project Tiger, Mr. Modi released 3,167, and much of the coverage set it against 2018’s 2,967 as a rise of about 200. The two numbers measured different things. The first counted only camera-trapped space, the second the full modeled estimate, Aathira Perinchery wrote in The Wire. The modeled 3,682 followed in July.
The case against the curve
Dr. Arjun Gopalaswamy, a statistical ecologist then at Oxford, led the first broad statistical attack. His 2015 paper in Methods in Ecology and Evolution, written with Dr. Karanth and others, tested index calibration, the step that converts signs like scat and tracks into tiger numbers. “Our study shows that index-calibration models are so fragile that even a 10 percent uncertainty in detection rates severely compromises what we can reliably infer from them,” he said at the time, Digital Journal reported. Dr. Jhala answered in The Times of India: “Mathematics does not get outdated.”
The institute’s formal reply, published in PeerJ in August 2019 by Dr. Qureshi, Rajesh Gopal of the Global Tiger Forum and Dr. Jhala, said the critics’ calibration data paired sign and abundance surveys taken up to several years apart, and called their conclusions “highly questionable.” The critics came back that November in Conservation Science and Practice, arguing that sampling-based overdispersion made the 2014 estimates misleading.
A 2022 perspective in PNAS, by Dr. Gopalaswamy and seven co-authors including the lion biologist Craig Packer, laid out the ecological objections. Each four-year round had reported increases of 20 to 35 percent. Densities in the main breeding populations fell as the sampled area grew. The data implied that tigers moved en masse from marginal forest into core reserves between 2006 and 2010 and then reversed course between 2010 and 2014. The authors used the term “political populations” for wildlife numbers that serve an agenda more than the evidence.
In practice, reliable knowledge on abundance of a species may, at best, be achievable in small areas.
Dr. Ghazala Shahabuddin, a senior adjunct fellow at the Ashoka Trust for Research in Ecology and the Environment in Bengaluru, made the narrower case in the Down To Earth package. She called the method scientifically valid. Her point was that intensive camera sites tend to sit in good habitat, so extending their densities across the wider forest is likely to overstate tiger numbers. She set the 21.4 percent rise in camera locations and the 22.6 percent rise in walking against the 25.1 percent rise in photographed tigers, and wrote that the reported trends “may not be completely reliable.” In the same package Dr. Gopalaswamy argued that the reserve-level estimates could be too high by 350 to 900 tigers.
Dr. Karanth’s objection is to the whole national exercise. The surveys were “conducted in smaller areas in a shoddy manner, violating basic statistical assumptions,” he told Mongabay India in August 2023.
The data from all six surveys between 2006-2022 are hidden away and not shared with independent scientists, preventing states and independent researchers from doing better quality surveys with genuine expertise.
The case for the count
Dr. Qureshi has defended the method as a clean break from the pugmark era, which he told Scroll was “ripe for human error and not scientifically sound.” Of spatially explicit capture-recapture he said, “It is the most robust method used worldwide.” On double counting, he told Down To Earth that tigers shared between neighboring states, such as Karnataka and Kerala, are reconciled by the spatial models: “Thus duplication is removed.” More than 40,000 people collect the data, he said.
We are not here to increase or decrease tiger numbers. Our job is to be as authentic as possible.
The government scientists have also put their range figures through peer review. A paper in Science on Jan. 30, 2025, by Dr. Jhala, Ninad Mungi, Mr. Gopal and Dr. Qureshi, reported that the area tigers occupy grew 30 percent over two decades, at 2,929 square kilometers a year, to about 138,200 square kilometers. Tigers vanished where armed conflict, poverty and land-use change were heaviest. Dr. Gopalaswamy told The Associated Press that the official estimates had been “chaotic” and “contradictory,” but said the paper appeared to resolve an inconsistency between population and range that scientists had raised since 2011.
The count has also recorded losses. Tigers photographed in the Western Ghats fell to 824 in 2022 from 981 in 2018, and reserves in Mizoram, Nagaland and Jharkhand recorded no more than one tiger each, Mongabay reported. Dr. Jhala told Mongabay that numbers could “easily go up by another 1500.”
What the evidence supports
The floor holds up. Three thousand and eighty tigers matched by stripe pattern is a list of animals, not a model’s output. Even an error rate of 16 percent, the most the Express investigators found in 2014, would leave about 2,600 tigers photographed in 2022, far above the 1,411 the whole country was credited with in 2006. That is a different kind of claim from the pugmark era’s, when a reserve could report two dozen tigers that were not there.
The rate is weaker. Photographed tigers rose by 619 between 2018 and 2022 while the survey added 33 sites and thousands of camera locations. Capture-recapture corrects for missed animals within a site. It cannot tell a newly born tiger from one that was always living in forest no one had sampled before. An unnamed tiger biologist made the same point to The Wire in April 2023, noting that 5,750 more cameras had been used and new sites may have been sampled. Without site-by-site data, how much of the 619 came from newly watched forest can’t be determined.
The baseline is the softest number in the series. If the 1,411 of 2006 was too low, as Dr. Karanth argues, the doubling and the 6.1 percent annual growth are partly an artifact of the start date. The modeled sixth, roughly 600 tigers in 2022, is where Dr. Shahabuddin’s habitat-bias argument bites, and it is the part most likely to grow as cameras move into buffer zones and corridors.
None of this can be settled from outside. The government’s critics have published their objections in peer-reviewed journals, and so has the institute. Neither can rerun the other’s analysis without the photographs and detection histories, which the Nature editorial and Dr. Karanth say remain unavailable to independent scientists. When Scroll asked the tiger authority to comment for its 2023 article, it did not respond.
People on the ground
Before the statistics there were trackers. Prem Bahadur Rai, a hunters’ tracker, found tigers for a Smithsonian team collaring them in Nepal, and the Nepalese scientist Hemanta Mishra wrote that he could never have collared tigers without him. Dr. Karanth’s early team was Jenu Kuruba tribesmen who read tracks he has said were beyond him.
A researcher Alter identifies only as Kazmi, who has walked with many Adivasi trackers, said pugmark work was never entirely fruitless and is an art that takes a lifetime to learn. Most of that knowledge is already lost, Mr. Kazmi said, and the rest will be gone in 10 to 15 years without an effort to keep it. The census still runs on walking. Dr. Dipankar Lahkar, a senior conservation biologist at the nonprofit Aaranyak who has helped run it in northeast India, said volunteering means long hikes with few facilities on the same route every day. Praveen Bhargav, who heads Wildlife First, has often said technology multiplies field effort only when there are people in the forest.
The sixth count
Fieldwork began nationwide in January and covers 58 tiger reserves, up from 51 in 2022. Gujarat, which had no verified tiger record from 1989 until a young male settled near Ratanmahal on the Madhya Pradesh border in early 2025, joins for the first time, as does Sikkim, The Tribune reported. Its account describes “AI-assisted image classification, expert verification and statistical modelling” layered together.
The tiger authority marked the cycle’s launch on X, calling it two decades of the world’s largest wildlife survey.
The All India Tiger Estimation (AITE) began in 2006. Since then, 5 cycles have been completed (2006, 2010, 2014, 2018, 2022) — each refining science & scale. Now, the 6th cycle in 2026 will mark two decades of the world’s largest wildlife survey.#aite #Tigers #wildlife #India
In Uttar Pradesh, about 1,800 cameras ran in four reserves and nearby forest from November 2025 to April, and more than 150,000 images went to the institute in June, H. Rajamohan, field director of Dudhwa Tiger Reserve, told the Press Trust of India. Dudhwa’s tigers rose from 82 to 135 between the 2018 and 2022 counts, a 64 percent increase, and Mr. Rajamohan said he expected more.
Environment ministry sources told ThePrint in January that initial estimates pointed to a rise of 10 to 15 percent, mostly outside reserve cores, in buffer zones, territorial divisions and corridors. Those are the forests where cameras are newest. In August 2025 The Tribune wrote that the report would come out in 2026. With two months left in the year, the national report is now expected in July 2027, according to ThePrint.