Improved tiger numbers come with hidden messages on invasives, habitat connectivity

Oct 02, 2023

India is now home to at least 3,682 tigers – a new record that surpasses earlier estimates, according to the latest government data. The Ministry of Environment, Forests and Climate Change released its detailed All India Tiger Estimation quadrennial report on July 29, which states that the “upper limit” of the tiger population could be even higher, at 3,925 individuals.

Earlier, in April, to commemorate the 50 years of Project Tiger, Prime Minister Narendra Modi released an initial estimate of 3,167 tigers in the country based on the data from areas with camera traps. The latest estimate, however, includes numbers of tigers that roam outside the camera trapped areas too.

These numbers reflect “commendable growth,” which have made India home to almost 75 percent of the world’s wild tigers, the Ministry said in a statement. But even as tiger numbers have shown massive improvement, the 494-page report, authored by the National Tiger Conservation Authority (NTCA), warns of challenges posed by habitat fragmentation, invasive species and dwindling funds, to future conservation efforts. “Out of approximately 5,83,278 square kilometres of forests in the tiger states, only one-third are in relatively healthy condition,” says the report.

Tiger populations, however, have not grown uniformly across the country, with reserves in Central India, the Shivalik Hills and Gangetic Plains witnessing the most improvement in terms of absolute numbers. Reserves in the Northeast and Brahmaputra regions showed the least growth.

“Areas that have historically done well, continue to do well, but states that fared poorly in the past continue to deteriorate. This may have to do with bushmeat consumption, poor law and order enforcement and poverty in some states,” said Y.V. Jhala, former Dean at the Wildlife Institute of India, a leading institution on wildlife research and management.

Some experts have also pointed to lack of transparency in the data collection process in the NTCA report.

India has 53 tiger reserves spread across 75,796 square kilometres. Approximately 35 percent of these reserves urgently require “enhanced protection measures, habitat restoration, ungulate augmentation, and subsequent tiger reintroduction,” according to the government’s report.

In recent years, over 80,000 hectares of forest land have been diverted for infrastructure projects. On August 2, the Rajya Sabha passed the Forest Conservation Amendment Bill, which makes exceptions to certain projects for forest land diversion.

Read more: Controversial FCA amendment bill passed in Lok Sabha

The government credits the Management Effectiveness Evaluation (MEE), a framework developed by the International Union for Conservation of Nature and Natural Resources (IUCN) for the management of India’s tiger reserves. The MEE is a checklist of 33 parameters that examine planning, financial resources, personnel and species diversity, among others. None of the 51 reserves evaluated in the latest cycle fall in the “poor” category, according to the government’s report.

Madhya Pradesh continues to host the highest number of tigers in the country, at 785. Along with Madhya Pradesh, Karnataka, Maharashtra and Uttarakhand, which house 563, 560 and 44 tigers each, have shouldered the bulk of India’s rise in tiger numbers.

The most densely populated tiger reserve remains Corbett in Uttarakhand, with 260 tigers, followed by Karnataka’s Bandipur (150) and Nagarhole (141) reserves.

Reserves in Mizoram, Nagaland and Jharkhand reported zero to one tiger, which the report notes with concern. “It is clear that the forests of Chhattisgarh, Jharkhand, Odisha, parts of Bihar, southern Uttar Pradesh, and barring some prestigious protected areas in the North East (Kaziranga, Manas, and Orang) the entire region of the North East, is depleted of wild prey. Tigers from these areas have become locally extinct or persist at very low densities, which are not viable in the long term.”

The survival of tigers in the state of Odisha is of particular concern, the report says, because of poaching activities.

“Immediate action is required to combat poaching and protect the remaining tigers in Odisha, as failure to do so may lead to the extinction of this population. Efforts must be made to strengthen anti-poaching measures and raise awareness about the importance of conserving tigers in Odisha to ensure their survival for future generations,” the report adds.

According to Jhala, tiger numbers could “easily go up by another 1500,” if reserves that have performed poorly, improve.

The survey was conducted across three phases. The first phase included field data from 21 potential tiger bearing states, in which frontline staff recorded signs of carnivores, herbivores, human disturbance, vegetation, and other factors. The second phase included remote sensing of covariates that could influence wildlife distribution and abundance, such as human footprints, distance to nightlights, and forest patch size. The third phase included camera trap capture. Camera traps were placed at 32,803 locations spread across 175 sites.

“The spatially explicit capture recapture approach was used to calibrate estimation in camera-trapped areas and extrapolate to areas where tigers are present but not camera-trapped,” says the report.

Apart from tiger numbers, the report also surveys large herbivores and vegetation across the country. For the first time ever this year, it also sheds light on the threats to biodiversity posed by invasive plant species. The report finds that 750,905 square km of natural areas – 65 percent – were found suitable for invasion by the high-concern invasive plants. Around 254,880 square kilometers were already found to be invaded by at least one high-concern invasive plant.

Linear projects and deforestation are among the biggest drivers of invasive plant species, studies have found. Linear projects and development also lead to habitat fragmentation. “A reassessment of the corridors across tiger landscapes shows that the source populations are connected through tenuous, narrow habitat patches that may shrink or be completely lost in the near future, unless brought under a conservation agenda. These connectivity areas are under huge anthropogenic pressure and losing them would restrict tiger dispersal in the landscape, leading to tiger-human conflict and the eventual extinction of tiger,” says the report.

“We now know that invasive plants are slowly reducing native plants that act as nutritious forage for wild herbivores. Loss of native forage is reducing wild herbivore habitat use, which over time can reduce their population and threaten the sustenance of tigers in the long run,” said Ninad Mungi, a postdoctoral researcher at Aarhus University in Denmark whose work on invasive species is cited in the NTCA report. Mungi was citing research by Rajat Rastogi, a former post graduate student at the Wildlife Institute of India. “This is fortunately a slow process, which gives us a window of time to intervene and prevent the loss of native plants or herbivores,” he added.

The tiger estimation report ranks core tiger areas and national parks as the first priority for restoration work, followed by other natural areas. “We considered least invaded native ecosystems to have the highest conservation priority, as impacts from invasive species would be minimal and the investments in terms of monitoring and removing invasive plants in their early stages would be minimal,” it says. However, only 16 per cent of invaded areas are feasible to restore as of now, it says. Some of the least invaded ecosystems are the deserts in western India and the wet evergreen forests of in the northeast region.

“Now that India knows where to start restoration, it can give a boost to on ground actions. Restoring native ecosystems is a complex and long-term process that requires reinforcing ecological processes that can make the system resilient to disturbance. India might now need a comprehensive plan shaped by central policy to start long-term large scale restoration programs. It will not only help recover native plants, animals including the tiger, but also strengthen the ecosystem services critical for human well-being,” said Mungi.

Some experts cautioned that the data collection in the census process could benefit from more transparency.

“These numbers are generated on the basis of camera trap capture and recapture surveys conducted in smaller areas in a shoddy manner, violating basic statistical assumptions,” said Ullas Karanth, tiger expert and Director of the Centre for Wildlife Studies.

“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,” he said.

Banner image: New estimates peg India’s tiger population at 3,682, a new record. Photo by Brian Gratwicke/Wikimedia Commons.