Western Ghats Wildlife Faces Grave Threat from Road Mortality, Study Reveals
A groundbreaking multi-institutional study has shed light on the devastating impact of vehicle collisions on wildlife in the Western Ghats, one of the world's most critical biodiversity hotspots. Published in the Journal of Wildlife Science of the Wildlife Institute of India, the research documents a staggering 6,507 animals from 239 different species killed on roads between 1997 and 2023.
Detailed Breakdown of Wildlife Casualties
The comprehensive analysis reveals that of the total animals killed, 4,960 were vertebrates and 1,547 were invertebrates. The vertebrate toll included 166 species, comprising 21 amphibians, 74 reptiles, 40 birds, and 31 mammals, along with 73 invertebrate species. Alarmingly, approximately 51% of the vertebrate species documented were endemic to the Western Ghats, underscoring the unique ecological loss.
Reptiles accounted for the highest proportion of species killed, with snakes bearing the heaviest burden. A shocking 43% of snake species recorded were victims of roadside kills. Among individual animals, amphibians made up the largest share of vertebrate deaths at 52%, followed by reptiles at 30%.
Conservation Crisis: Threatened Species at Risk
The study identified 18 species listed under IUCN threatened categories—critically endangered, endangered, or vulnerable—among the roadkill victims. This finding accentuates the conservation significance of road mortality in this ecologically sensitive region. Furthermore, out of the 239 species documented, 103 were listed under different schedules of the Wildlife (Protection) Act, 1972, as amended in 2022.
Notable vulnerable species recorded as roadkill included the bonnet macaque, leopard, Western Ghats king cobra, Indian star tortoise, spiny tree mouse, Nilgiri langur, Sambar deer, Phipsons shieldtail, two-lined black earth snake, shorhead kukri snake, and Indian flap-shell turtle.
Geographical Scope and Data Limitations
The research covered the extensive 26,482 km road network in the Western Ghats, which includes national highways, state highways, and rural roads. However, the authors noted a geographical bias in available data, with most studies conducted on the eastern slopes of the southern Western Ghats.
The study also revealed that nearly 53% of recorded vertebrate mortalities could not be identified to the species level, highlighting gaps in monitoring and research.
Alarming Mortality Rates and Estimates
The overall estimated mortality rate was 0.014 kills per kilometer, 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.
Based on published road mortality rates, researchers calculated conservative daily roadkill estimates for the entire Western Ghats road network:
- Invertebrates: 19,067 - 36,35,979
- Amphibians: 530 - 10,59,280
- Reptiles: 530 - 1,30,026
- Birds: 159 - 2,383
- Mammals: 159 - 20,920
Even when considering the lowest mortality rates for each taxon, the annual estimates remain alarmingly high: 1,93,450 amphibians, 1,93,450 reptiles, 58,035 birds, and 58,035 mammals.
Species Most Frequently Killed
The study identified that species most affected by road mortality in terms of the number of road-killed individuals found varied between sites and studies. However, Asian toad, Oriental garden lizard, Shieldtail snakes, and Vine snakes were reported to be killed most frequently across the study locations.
Call for Collaborative Conservation Action
The authors emphasized that their review underscores the urgent need for collaborative efforts among researchers, policymakers, and conservationists to develop wildlife-friendly road infrastructure in this ecologically sensitive region. They stress that without immediate intervention, road mortality will continue to threaten the unique biodiversity of the Western Ghats.
The study, titled 'Dark side of Development: A review on Road Mortality of Wildlife in the Western Ghats Biodiversity hotspot', was authored by Arjun Viswa Sansthasivam and Moorthi Mahaly from the PG and research department of zoology and wildlife biology at AVC College (autonomous), Tamil Nadu, along with Babu Santhanakrishnan and Arun P Ramachandran from the Salim Ali Centre for Ornithology and Natural History (South India Centre of Wildlife Institute of India). The research took 32 peer-reviewed papers into consideration, providing the most comprehensive assessment to date of this critical conservation issue.
