An Asian wild dog or dhole. Photo: Davidvraju/Wikimedia Commons, CC BY SA 4.0
- Eight top predators found in India, including the sloth bear, tiger and dhole, are among the world’s most vulnerable due to road accidents, a new study finds.
- The results of the study could still be underestimated as in many countries, including India, wildlife mortality and other consequences of road traffic are not well quantified.
- When roads in natural areas cannot be avoided, species-specific mitigation measures and raising awareness among stakeholders are important to minimize the impact, experts say.
cooking: Eight apex predators found in India — including the sloth bear, tiger and dhole — are among the world’s most vulnerable due to the impact of roads, a new study reports. More roads in these animals’ habitats will mean more consequences for these species.
This comes at a time when conservationists across the country have been crying their hearts out over roads quickly becoming a growing concern for not just predators but other wildlife as well. Roads cut up animal habitats – and then put them at risk of being killed by vehicles speeding on those roads.
We’re not implementing enough mitigation measures—like underpasses—even in key wildlife corridors. Some only exist on paper.
The government will build more roads while widening others. According to the 2022 Union budget, a further 25,000 km of national highways will be expanded in India this year alone. How is our wildlife doing?
roads that kill
Roads affect biodiversity in many ways. They fragment habitats. In 2020, scientists found that linear infrastructure, including roads and power transmission lines, has led to a 6% increase in the number of tropical forest areas across India and a reduction in the number of large areas (larger than 10,000 km²).
“Road avoidance” is a known behavior. Research has shown that some species, such as deer, tend to avoid roads. This can result in reduced species richness in these areas, which can impact the viability of species in these landscapes.
Crossing roads to get to different habitat fragments can be lethal to wildlife. Roadkills are the order of the day, especially in India with its extensive road network – the second largest in the world with a total road length of 63.7 lakh kilometers. 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 Himalayas in UT of Jammu & Kashmir. Among the species killed was the Himalayan vulture, which was classified as “Near Threatened” on the IUCN Red List.
To quantify the impact of roads on apex predators around the world, scientists from institutes such as the Université de Poitiers in France reviewed literature on 36 predators (including lion, tiger and cheetah) and a database of wildlife-vehicle collisions between Curated 1963 and 2021.
The team also quantified each species’ “road hazards.” This index accounted for the species’ exposure to roads based on road density per square kilometer (which shows how fragmented their habitat is due to road networks) and species’ vulnerability based on their IUCN -Status.
Asia a hotspot
The study found that all 36 types of roads are affected, but to varying degrees. Of the 10 most endangered species, eight are found in Asia. These are 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 is most affected – widespread on the Indian subcontinent. It boasts the highest road density of any type, averaging a whopping 303 m per square kilometer. Almost 97% of its distribution is covered by roads, and “this high exposure contributes significantly to habitat fragmentation and increased mortality from vehicle accidents,” the authors write in their article.
“From 2012 to 2017, 15 sloth bear roadkills were recorded in India…this mortality rate poses a serious threat to this species.”
The striped hyena also showed a high risk from road impact, the study found. While the species is found in both Africa and Asia, Asian populations — particularly in South Asian countries — are more exposed to roads, the study found. In India, the striped hyena is found in most of the central, western and northern regions.
Roadkills of this kind are not uncommon. In southern Odisha, for example, scientists found 123 dead vertebrates — including 14 species of mammals, including the striped hyena — over a 90-day period last year on a stretch of NH-16.
The IUCN Red List does not currently list the striped hyena, dhole or tiger as “threatened” by transport infrastructure, but the study found 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 yet well quantified. Roadkill databases are not updated often, even if they exist. Media reports cover some cases but not all.
Quantifying animal mortality on roads is likely always to be an underestimate unless we have systematic and regular surveys both inside and outside of protected areas, said P. Jeganathan, researcher at the Nature Conservation Foundation and author of the Valparai study.
Aside from two specific studies, including one published in February 2022, there doesn’t appear to be any on how roads affect sloth bears in India, he said. “More such studies should be done for all taxa (not just large mammals) to get a fuller picture in India (and other developing countries),” he wrote in an email The Wire Science.
Another aspect we need to take into account is that animals that are injured on roads but die as a result are not recorded anywhere, he added.
More roads, more effects
According to the study, “the expected rapid increase in road construction in developing countries will increase the risk of apex predators and their habitats”. Nepal’s 1,800km Postal Highway project, for example, aims to connect 20 districts in southern Nepal’s southern Terai belt and will pass through a number of protected areas. Not only will it affect eight protected areas in Nepal, but five protected areas in the country that also border India, the study said.
Similarly, more road infrastructure is being built in India as well. According to the latest economic survey, road construction increased to 36.5 km per day in 2020 from 28 km per day in 2019. business standard reported.
On February 1st this year, Union Finance Minister Nirmala Sitharaman announced in her budget speech that India would expand its National Highways network by 25,000 km this year. The allocation for the Ministry of Roads and Highways thus increased by 68% to Rs. 1.99 billion.
A few days later, Nitin Gadkari, Union Minister for Transport, submitted in a written reply to Rajya Sabha that some sections of about 100 National Highways fall into or pass through forest areas that have been declared “wildlife sanctuaries”, “national parks” or their ” eco-sensitive zones”. In order to “minimize” the impact of the highway expansion on wildlife, the ministry has directed enforcement agencies to avoid routing roads through such protected areas, even if it requires a longer route/detour, he added.
“Given the current and future scale of road development in India, the watering down of environmental laws, particularly wildlife segregation and deforestation, and the non-existent lack of oversight by the [environment ministry] and the [National Tiger Conservation Authority] Due to severe capacity constraints, government claims that wildlife will not be affected are just greenwashing,” said researcher Milind Pariwakam of the Wildlife Conservation Trust in Mumbai. He has studied the impact of roads on wildlife in Central India.
For example, State Highway (SH) 43 was built by “violating all environmental laws and completely ignoring mitigation measures proposed by NTCA and the National Board for Wildlife,” he said. This highway in southern Madhya Pradesh has been expanded “at the expense of the Satpura-Melghat-Pench Tiger Corridor” spanning Madhya Pradesh and Maharashtra through which it passes. Indian times reported.
Conservationists have claimed that the Madhya Pradesh Road Development Corporation circumvented forest and wildlife laws for the extension; Although several mitigation actions were recommended, none were implemented.
Mitigation measures are changes that can be made to roads to reduce the impact on wildlife. These include building underpasses or overpasses that wildlife can safely use as crossings, or putting rumble strips on roads to warn users to slow down in such areas.
But whatever mitigation measures we do may not be sufficient at all, according to Jeganathan.
“Roads through natural spaces (particularly the two- or four-lane ones) should be avoided and re-routed as much as possible,” he said.
The current study, which looked at road impacts worldwide, proposes four main ‘phases’ as a mitigation hierarchy – biodiversity prevention, minimisation, rehabilitation and compensation (where damage in one area is ‘offset’ or compensated for in another area). But for us (in India) to achieve the very first aspect by ourselves would be a difficult task or near impossible, he wrote.
Several steps could help, he added. You get a biologist to provide input on site- and species-specific mitigation measures when planning the road network (especially if it goes through natural areas, be it grasslands, scrubland or suburban areas).
Aside from the conventional way of implementing the mitigation measures, we need to think “out of the box” to educate the relevant stakeholders, he said. These could range from training engineers and including road ecology in their curriculum, to raising awareness of the negative impact of roads on wildlife among a range of stakeholders.
This includes road officials, road contractors, construction companies, local politicians and the general public (e.g. through Citizen Science programs). Promote research on the impact of roads before The planning phase – and not just “mere window dressing”, environmental impact assessments or post-road studies – is also important, he said.
“[These] may sound crazy and utopian, but if we don’t take such steps, we will lose our precious wildlife every minute. Not just one or two, but [in] Thousands of single kills per km per year,” he wrote.