Middle paths Environment

A wild, wild road

A deer is hit by a truck as it tries to cross NH37 inside the Kaziranga National Park   | Photo Credit: Ritu Raj Konwar

When Bilal Habib, a scientist with the Wildlife Institute of India (WII), Dehradun, fixed camera traps on the pillars of nine underpasses beneath a stretch of National Highway 44 — India’s longest highway from Srinagar to Kanyakumari — he found, amid hundreds of images of people, cattle and street dogs, a world of wildlife far vaster than he expected.

Two days after the cameras were installed in March this year, a female tiger was photographed strolling through one of these underpasses. Within the next three months, a pack of wild dogs was filmed hunting a spotted deer; then there was a leopard, a gaur, a sloth bear, civet cats, and thousands of langurs. They used the underpasses mostly at night but sometimes also by day; some in garrulous groups, others solitarily; they used them to nap, to play among their pack, to hunt, but most often, just to get to the forest on the other side of the road.

These nine ‘animal underpasses’ were built late last year beneath a stretch of NH 44 on one of the country’s most important wildlife corridors, between Kanha and Pench tiger reserves in Madhya Pradesh and Maharashtra, to prevent roadkill and reduce the ‘barrier effect’ that busy roads have on the movement of animals. And, according to a WII report, 18 species used the underpasses between March and May. Notably, among the large carnivores, the most frequent one on camera was the tiger: 11 individual big cats used every one of the nine underpasses, including tiger T1 of Pench who was famously filmed two months ago pondering a meandering stretch of NH 44 in Maharashtra before cautiously crossing it and leaping over the crash barrier into the forest.

Far from perfect

These underpasses are India’s first examples of ‘wildlife mitigation measures’ or attempts to remedy the impact of infrastructure on wild animals, and were achieved after a 10-year-long legal battle between environmentalists and NHAI. When a plan to expand the highway from two to four lanes was announced, a group of NGOs and activists submitted a petition to the Supreme Court’s Centrally Empowered Committee in 2008 calling for an alternative alignment to avoid the Kanha-Pench corridor. NHAI’s project got approval, but it was ordered by the court to create mitigation measures.

A tiger crosses an underpass beneath NH 44 in the Kanha-Pench corrdor

A tiger crosses an underpass beneath NH 44 in the Kanha-Pench corrdor   | Photo Credit: WII

This hard-won victory for the environmentalists, however, has been partial. The underpasses are far from perfect, says one of the petitioners, Milind Pariwakam, a road ecologist with Wildlife Conservation Trust (WCT) Mumbai. Six of the nine underpasses are relatively small ‘bridges,’ and fewer species use them; none of them have barriers against light and noise; and the proposed pipe culverts for smaller reptiles have not been constructed.

With all these shortcomings, however, these nine structures have proved that wild animals do indeed use them, potentially reducing roadkill and creating habitat connectivity. But while they are an important first step, we must not lose sight of the bigger picture, says Pariwakam: “According to our calculation, some 55,000 km of roads pass through India’s forests and protected areas, many of them through wildlife corridors.”

NH 44 cuts through wildlife corridors connecting Kanha, Satpura, Pench, Bandhavgarh, Panna tiger reserves and at least four other protected areas. NH 6 — India’s second longest highway that runs across the breadth of the country from Surat to Kolkata — passes through corridors around Melghat, Bor, Nagzira, Simlipal tiger reserves and seven other national parks and sanctuaries. As Pariwakam says, “Dozens of roads are being upgraded on these stretches with no mitigation measures in place.”

A ‘Roadkills’ app that WCT developed recorded 3,500 wildlife deaths on roads across the country last year. “But that is just the tip of the iceberg — the undocumented roadkills could run up to millions,” he says. Just last month, a herd of three elephants was killed by a truck on NH20 in Odisha.

Impermeable walls

Highways don’t just mean roadkill: they degrade habitat, produce noise and light that disorient animals, they break canopy connectivity for arboreal animals such as the endangered lion-tailed macaque; and, where traffic is high in volume and velocity, they become impermeable walls that splice up habitats.

A gaur crosses a road running through Nagarjole National Park

A gaur crosses a road running through Nagarjole National Park   | Photo Credit: Suresh Basavaraju

For an animal like the tiger this can be disastrous, says Uma Ramakrishnan, molecular ecologist with the National Centre for Biological Sciences, Bengaluru. She is particularly concerned by the impact of highways on tigers in central India. “Central India’s tigers have the highest genetic variation among Indian tigers, and this has been made possible by the large habitats available here in the past. Our research has shown that when populations are isolated by linear projects, there’s the risk of inbreeding, of disease and ultimately of local extinction,” she says.

A study published last year in Biological Conservation, co-authored by Ramakrishnan, used genetic data collected from 10 central Indian tiger reserves including Pench, Kanha and Bandhavgarh, and predicted that if intrusions such as roads continue at the current rate, vital ‘heterozygosity’, or genetic variability, would decrease by as much as 50% in the next century.

“The euphoria over the 33% growth in tiger population should be tempered by the fact that wildlands can be fractured, creating islands of tiger habitats,” says Ramakrishnan.

Meanwhile, the environmentalists who fought for wildlife protection measures along NH 44, have seen a few major strategic victories. More underpasses have been commissioned on NH 44 and NH 6; and in May the Ministry of Road Transport and Highways wrote to the National Highways Authority of India and other road construction authorities saying that ‘all efforts shall be made to avoid any road alignment through National Parks and Wildlife sanctuaries unless absolutely unavoidable.’

“We should, wherever possible, avoid bisecting habitat or corridors with roads — not just in national parks and sanctuaries,” says Ramakrishnan. “And where this is not possible, mitigation measures should be planned: they translate to just a fraction of the total infrastructure cost, but mean a huge investment towards the long-term survival of species like the tiger.”

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Printable version | Sep 15, 2021 10:13:20 AM | https://www.thehindu.com/sci-tech/energy-and-environment/a-wild-wild-road/article29360610.ece

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