‘6,507 animals of 239 species killed in road collisions in Western Ghats over 26 yrs’

DEHRADUN: A study of Salim Ali Centre for Ornithology and Natural History (South India Centre of Wildlife Institute of India) and AVC College (autonomous), Tamil Nadu -- published in the Journal of Wildlife Science (JWLS) of Wildlife Institute of India (WII) -- has documented the scale of wildlife mortality from vehicle collisions across biodiversity hotspots of the Western Ghats, recording 6,507 animals of 239 species killed between 1997 and 2023.

Of these, 4,960 were vertebrates and 1,547 invertebrates.The study said that the vertebrate toll included 166 species — 21 amphibians, 74 reptiles, 40 birds and 31 mammals — along with 73 invertebrate species. Around 51% of vertebrate species were endemic to Western Ghats, the study said. Reptiles accounted for the highest proportion of species killed, with snakes bearing the heaviest burden — 43% of snake species recorded as roadside kill.

Among individual animals, amphibians made up the largest share of vertebrate deaths at 52%, followed by reptiles at 30%.The study noted that nearly 53% of recorded vertebrate mortalities could not be identified to the species level. The overall estimated mortality rate was 0.014 kills per km, though this varied widely — between 0.7 and 137.3 kills per km for invertebrates, and between 0.006 and 40 kills per km for vertebrates.

Eighteen of the recorded species were listed under IUCN threatened categories — critically endangered, endangered, or vulnerable — accentuating the conservation significance of road mortality in one of the world’s most ecologically sensitive regions. Out of 239 species, 103 were listed under different schedules of the Wildlife (Protection) Act, 1972, as amended in 2022.The road network in the Western Ghats is 26,482 km, which includes national highways, state highways and rural roads.

“Results reveal a geographical bias in the available road mortality data, with most studies conducted on the eastern slopes of the southern Western Ghats,” the study stated.Authored by Arjun Viswa Sansthasivam and Moorthi Mahaly of PG and research dept of zoology and wildlife biology, AVC College (autonomous), Tamil Nadu; and Babu Santhanakrishnan, Arun P Ramachandran of Salim Ali Centre for Ornithology and Natural History (South India Centre of Wildlife Institute of India), the multi-institutional study ‘Dark side of Development: A review on Road Mortality of Wildlife in the Western Ghats Biodiversity hotspot’, took 32 peer-reviewed research papers into consideration.The authors noted that roadkills included vulnerable species such as bonnet macaque, leopard, western ghats king cobra, India star tortoise, spiny tree mouse, Nilgiri langur, Sambar deer, Phipsons shieldtail, two-lined black earth snake, shorhead kukri snake and Indian flap-shell turtle. Species most affected by road mortality in terms of the number of road-killed individuals found varied between sites and studies.

Asian toad, Oriental garden lizard, Shieldtail snakes and Vine snakes were reported to be killed most frequently across the study locations, according to the study.Based on the published road mortality rates, researchers calculated a conservative estimate of daily roadkill of wild animal individuals (kills/visit) for the entire road network in Western Ghats, it estimated: “19,067 - 36,35,979 (invertebrates); 530 – 10,59,280 (amphibians); 530 - 1,30,026 (reptiles), 159 - 2383 (birds), and 159 to 20,920 (mammals),”Even when considering the lowest mortality rates (kills) for each taxon, “the annual estimates of the roadkill (for 365 days) for vertebrates (amphibians: 1,93,450; reptiles: 1,93,450; birds: 58,035; and mammals: 58,035) in the Western Ghats is alarmingly high,” said the study.The authors added, “Review underscores the need for collaborative efforts among researchers, policymakers and conservationists to develop wildlife-friendly road infrastructure in this ecologically sensitive region.”