Pune: The feel-good factor was undeniable when the International Union for Conservation of Nature (IUCN) revealed its assessment last month that wild tiger numbers had increased worldwide by 40 per cent between 2015 and 2022, from 3,200 to 4,500. But these numbers are important not just because they paint a brighter picture of the tiger population, but because they provide a more accurate one by filling in key gaps in data.
According to the IUCN — which tracks the conservation status of endangered plants and animals — there are currently 3,726 to 5,578 tigers in the wild. The animal is still considered “endangered” on IUCN’s Red List of Threatened Species, but there has been an improvement from the all-time low estimate of about 3,000 in 2010, the year when the Global Tiger Summit in St Petersburg, Russia, pledged to double the numbers by 2022. Many conservationists who were sceptical then are cautiously optimistic now.
But other than the apparent upward trend itself, the IUCN report (available for download on iucnredlist.org) claims that its population data is the “first reasonably rigorous estimate” of global tiger numbers and sets a “realistic baseline” for future evaluations.
This matters because even though tigers have been widely studied and have been the ‘postercats’ for conservation efforts for the past 50 years, there was a lack of accurate baseline data.
Reliable population baselines, experts agree, are essential to monitor population trends and also to come up with effective conservation and management plans depending on where tigers are distributed, how many there are, and so on.
Previously, tiger populations were estimated by extrapolating numbers from surveyed areas — like tiger reserves and national parks — to get ballpark figures for the entire range where tigers were known to occur.
However, the latest data comes from better tracking and counting methods, like camera-trapping — where strategically placed motion-sensor cameras provide images and data about animals with minimal human intervention — and wider survey areas.
“We have a much better understanding of tiger numbers now than we did six or seven years ago,” said Abishek Harihar, the deputy director of the tiger programme of the conservation organisation Panthera, and one of the co-authors of IUCN’s assessment report. “For once, we have a comprehensive baseline… the previous ones are tough to defend.”
Earlier gaps in tiger data
The IUCN’s latest assessment report points out many flaws in previous estimates of tiger numbers, cautioning that these suffered from a “lack of scientific rigour and poor range-wide sampling coverage”.
The previous baselines comprised a 1996 assessment, which estimated there were 8,296 tigers, and another from 1998 that put the global population of the species at 5,000 to 7,000. The report pointed out that neither of these estimates were based on significant field surveys.
Further, the 2022 IUCN report said that these two estimates did not mention the age of the tigers they analysed. Given the “low quantity and quality of data” back then, the report surmised it is possible that the two older assessments included tigers younger than three years of age, which is problematic since many juveniles do not survive till adulthood in their quest to hone their hunting skills and establish their own territories.
In the case of the IUCN’s 2015 assessment of tigers, the report cautioned that it was likely an undercount of mature animals since it included only protected areas that were large enough to contain 75 adult tigers, and excluded many smaller pockets known to have breeding tigers.
Filling in the gaps
Between 2015 and 2018, under an old programme called Tiger Conservation Landscapes — which identified areas where tiger numbers could recover as well as those which had not been previously surveyed — there was a substantial revision in tiger numbers inside and outside of Protected Areas (PAs).
It also helped that there were better techniques for making estimates, providing a clearer demographic picture.
For instance, an older estimate based on 2005-2007 data, gathered by using methods like pugmark analysis, indicated that the Bangladesh Sundarbans supported 335 to 500 tigers. But now the estimate has been revised down to 84 to 158 thanks to photographic capture-recapture sampling and genetic data (samples, like hair, are collected non-invasively).
In Bhutan, on the other hand, the first estimate of tiger numbers, in 1988, came from “social surveys and anecdotes”. The hill kingdom got its first reliable baseline only after a 2014-15 photographic capture-recapture sampling, putting the number of tigers here at around 100.
“It is the precision of estimates that increases when more data is available,” Pranav Chanchani, national lead for tiger conservation at WWF India and one of the co-authors of the IUCN report, said.
What the new data reveals
The latest IUCN assessment points to important trends in tiger demographics, giving governments and scientists a more accurate picture of how tiger populations are faring in their countries.
This information could enable efficient allocation of funds and resources as well as monitoring of tigers. In areas where tigers are doing well, funds could be allocated for continued assessment and protection. In areas where they are not, funds could be used for recovery by focusing on increasing prey animals, and personnel for protection on ground.
Broadly, tiger numbers are increasing in South Asia, particularly in India, Nepal, and Bhutan, while they are stable in the Russian far east and in areas along the Russia-China border. In Southeast Asia, the situation is far worse, with the species having been lost from Cambodia, Laos, and Vietnam since the turn of the century.
The IUCN data also puts the focus on conserving “source sites” — qualified as areas that have 25 or more adult breeding female tigers.
Source sites are critical as young adult tigers disperse out of these to new areas, where tiger densities are lower, in order to establish their territories.
“Through the processes of dispersal and colonisation, source sites can enable tiger recovery in areas of conservation landscapes where the species populations are depleted,” Chanchani said.
A number of India’s tiger reserves, including Kaziranga, Kanha, Corbett and Nagarhole act as source sites. Others, like Palamau and Sariska, are too sparsely populated to qualify.
Whether or not source sites can result in the recovery of tigers depends on whether there are corridors for the animals to pass through so they can occupy any available surrounding habitat.
“Otherwise you will see more reintroductions in areas where tigers are no longer found,” Harihar said, in a reference to “resettlement” plans like in MP’s Panna Tiger Reserve, where the big cat’s numbers had dwindled to zero by 2009, after which tigers from other reserves had to be translocated to repopulate it.
Perhaps the greatest challenge ahead is habitat fragmentation due to infrastructural development, like roads, which could make it difficult or impossible for tigers to move from one PA to another.
“It is not about whether development happens or not, it is about how it happens,” Chanchani said, adding that it could come down to whether a road could be realigned to protect a corridor. “Doing a lot of this would be the key because in 10 years there will be no going back.”
Although India has managed to nearly double its tiger population to about 3,000 since the 2010 pledge, the world has fallen short of its target. With stakeholders due to gather again in Vladivostok, Russia, in September for the second International Tiger Conservation Forum, they would do well to take note of this latest assessment as they chart the future of tigers.
This report has been updated with a tweak in the first quote by Pranav Chanchani.
(Edited by Asavari Singh)