An Asiatic wild dog, or dhole. Photo: Davidvraju/Wikimedia Commons, CC BY SA 4.0
- Eight apex predators found in India, including the sloth bear, tiger and dhole, are most at risk worldwide due to road accidents, a new study has found.
- The study’s results could still be an underestimate because in many countries, including India, wildlife mortality and other consequences of road transport are not well-quantified.
- If roads can’t be avoided in natural areas, species-specific mitigation measures and increasing awareness among stakeholders will be important to minimise impact, say experts.
Kochi: Eight apex predators found in India – including the sloth bear, tiger and dhole – are among the most at risk globally due to the effects of roads, a new study has reported. More roads in these animals’ habitats will mean more consequences for these species.
This comes at a time when conservationists in the country have been crying themselves hoarse about how roads are fast becoming a growing concern for not just predators, but other wildlife too. Roads cut up animal habitats – and then put them at risk of being killed by vehicles speeding on those roads.
We’re not putting in place enough mitigation measures – such as underpasses – even in crucial wildlife corridors. Some exist only on paper.
The government is going to build even more roads, while others are going to be widened. As per the 2022 Union budget, India will see an additional 25,000 km of national highways being developed this year alone. How can our wildlife cope?
Roads that kill
Roads impact biodiversity in numerous ways. They fragment habitats. In 2020, scientists found that linear infrastructure including roads and power-transmission lines have caused a 6% increase in the number of tropical forest patches across India, and a reduction in the number of large patches (greater than 10,000 sq. km).
‘Road avoidance’ is a known behaviour. Assessments have shown that some species, such as deer, tend to avoid roads. This can lead to lower wildlife abundances in these areas, which can impact the ability of species to survive in these landscapes.
Crossing roads to get to different habitat fragments can be fatal for wildlife. Roadkills are commonplace, especially in India with its extensive road network – the second largest in the world, with a total road length of 63.7 lakh km. Almost 3,000 animals died on around 1,500 km of roads that researchers surveyed in 2012 in Tamil Nadu’s Valparai plateau.
Last year, researchers counted 49 animal carcasses along a 120-km stretch of National Highway (NH) 244, which runs through the Himalaya in the UT of Jammu & Kashmir. Species that were killed included the Himalayan vulture, which classified as ‘near threatened’ in the IUCN Red List.
To quantify the impact of roads on apex predators across the world, scientists from institutes including the Université de Poitiers in France reviewed literature on 36 predators (including the lion, tiger and cheetah) and curated a database on wildlife-vehicle collisions between 1963 and 2021.
The team also quantified each species’ ‘risks to roads’. This index took into account the species’ exposure to roads based on road density per sq. km (which shows how fragmented its habitat is due to road networks) and the vulnerability of species based on their IUCN status.
Asia a ‘hotspot’
The study found that all 36 species are affected by roads, but to different degrees. Of the 10 species most at risk, eight occur in Asia. These are the sloth bear, tiger, dhole, Asiatic black bear, clouded leopard, sun bear, Sunda clouded leopard and leopard. Except for the Sunda clouded leopard, all species are found in India.
The sloth bear – distributed across the Indian subcontinent – is the most affected of all. It faces the highest road density of all species, a whopping 303 m for every sq. km, on average. Almost 97% of its distribution is covered by roads, and “this high exposure significantly contributes to habitat fragmentation and increased mortality from vehicle collisions,” the authors wrote in their paper.
“From 2012 to 2017, 15 sloth bear roadkills were recorded in India … this level of mortality presents a serious threat for this species.”
The striped hyena also showed high risk from road impacts, the study found. While the species occurs in both Africa and Asia, Asian populations – especially those in south Asian countries – are more exposed to roads, the study points out. In India, the striped hyena is found across most of the central, western and northern regions.
Roadkills of the species are not uncommon. In southern Odisha, for instance, scientists found 123 dead vertebrates – comprising 14 mammal species including the striped hyena – on a stretch of NH-16 over a 90-day period last year.
The IUCN Red List does not currently list the striped hyena, dhole or tiger as being ‘threatened’ by transport infrastructure, but the study found that they are among the predators most at risk from roads.
Shockingly, the study’s results could still be an underestimate, as the authors themselves admit. That’s because in many countries, including India, wildlife mortality or other impacts are not well-quantified yet. Roadkill databases are not updated often, even if they do exist. Media reports cover some instances, but not all.
Quantification of animal mortality on roads is always likely to be an underestimate unless we have systematic and periodic surveys both within and outside protected areas, said researcher P. Jeganathan of the Nature Conservation Foundation, and an author of the Valparai study.
Apart from two specific studies, including one published in February 2022, there don’t seem to be any on how roads affect the sloth bear in India, he said. “More such studies should be conducted for all taxa (not just large mammals) to get a larger picture in Indian (and other developing countries),” he wrote in an email to The Wire Science.
Another aspect that we need to bear in mind is that animals that are injured on roads but die away from them will not be logged anywhere, he added.
More roads, more effects
According to the study, the “expected rapid rise of road development in developing countries will intensify the risk of apex predators and their habitats”. Nepal’s some-1,800-km-long Postal Highway project, for instance, aims to connect 20 districts in the southern Terai belt of south Nepal and will pass through a number of protected areas. It will affect not just eight protected areas in Nepal but five protected areas in the country that share boundaries with India too, the study says.
Similarly, India is seeing more road infrastructure being built too. According to the latest Economic Survey, road construction increased in 2020 to 36.5 km per day from 28 km per day in 2019, Business Standard reported.
On February 1 this year, Union finance minister Nirmala Sitharaman announced in her budget speech that India would be expanding its National Highways network by 25,000 km this year. Allocation for the Ministry of Road Transport and Highways thus increased by 68%, to Rs 1.99 lakh crore.
A few days later, Nitin Gadkari, Union road transport minister, submitted in a written reply to the Rajya Sabha that some stretches of about 100 national highways are falling in or passing through forest areas declared ‘wildlife sanctuaries’, ‘national parks’ or their ‘eco-sensitive zones’. To “minimise” the impact of highway development on wildlife, the ministry has issued instructions to implementing agencies to avoid road alignments through such protected areas, even if it requires taking a longer route/bypass, he added.
“Given the current and future scale of road development in India, the dilution of environmental laws particularly the delinking of wildlife and forest clearance, and the non-existent lack of monitoring by the [environment ministry] and the [National Tiger Conservation Authority] due to severe capacity crunch, claims by the government that wildlife will not be affected are just greenwashing,” said researcher Milind Pariwakam of the Mumbai-based Wildlife Conservation Trust. he has been studying the impact of roads on wildlife in central India.
For example, state highway (SH) 43 was built by “violating all environmental statutes and completely ignoring the mitigation measures suggested by the NTCA and National Board for Wildlife”, he said. This highway in southern Madhya Pradesh has been expanded “at the cost of the Satpura-Melghat-Pench tiger corridor” spanning Madhya Pradesh and Maharashtra which it passes through, Times of India reported.
Conservationists have alleged that the Madhya Pradesh Road Development Corporation bypassed forest and wildlife laws for the expansion; while several mitigation measures were recommended, none have been implemented.
Mitigation measures
Mitigation measures are modifications that can be made on roads to reduce impacts on wildlife. These include constructing underpasses or overpasses for wild animals to safely use as crossings, or setting up rumble strips on roads to alert users to slow down in such areas.
But whatever we do as mitigation measures may not be sufficient at all, per Jeganathan.
“Roads through natural areas (especially the two or four lanes) as far as possible should be avoided and realigned,” he said.
The current study that looked at road impacts globally proposes four main ‘phases’ – avoidance, minimisation, rehabilitation, and biodiversity offsetting (where damages in one area are ‘offset’ or compensated for in another area) – as the mitigation hierarchy. But for us (in India) to achieve the very first aspect itself would be an uphill task or near impossible, he wrote.
Several steps could help, he added. One is getting a biologist to provide inputs on location and species-specific mitigation measures during road network planning (especially if it passes through any natural areas, be it grassland, scrub forest or suburban areas).
Apart from the conventional way of implementing the mitigation measures we need to think “out of the box” to educate relevant stakeholders, he said. These could range from educating engineers and including road ecology in their curriculum, to increasing awareness about the ill effects of roads on wildlife across a range of stakeholders.
These include highways department officials, road construction companies, contractors, local politicians, and the general public (through citizen science programmes, for example). Encouraging research on impacts of roads before the planning phase – and not just as “mere eyewash” Environment Impact Assessments or studies after the road is constructed – would be important too, he said.
“[These] might sound crazy and utopian but unless we take such steps we will lose our precious wildlife each and every minute. Not just one or two but [in] thousands of individual kills per km per year,” he wrote.