Roads affect large mammal movement in Nagarhole Tiger Reserve, says a study

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An Indian Elephant (Elephas maximus indicus), crossing a  patrolling path at Nagarhole Tiger Reserve, Karnataka, India

 Constructing roads through protected areas will severely affect the wild life, reveals a recent study conducted on the Mysore- Mananthavady Highway which passes through Nagarhole Tiger Reserve, a major home for the big striped cat in South India.  According to the study, the road has caused certain large mammals to desert the adjoining areas while making some others more prone to be victims of road kill.

Comparing an abandoned segment with another one regularly used by the vehicles within a 20 KM distance, it was found that large mammals like Elephant (Elephas maximus indicus), Gaur(Bos garus) , Chital (Axis axis), Wild pig (Sus scrofa) and Tiger tend to avoid the road edges restricting themselves to other forest areas.

This does not mean that animals don’t usually use that place, but just avoid it. The study has found that 681 animal trails have intersected the portion of the road under study. However, the mean density of animal trails on the unused segment was 40 percent more than that in the used segment, indicating that the road is restricting natural wild life movement.

  

Swelling vehicle traffic

The study observed a startling 22 fold increase in vehicular traffic on this road which connects Wayanad district of Kerala with Mysore district of Karnataka, in seven years despite a traffic ban in the night.

According to Sanjay Gubbi, H. C. Poornesha and M. D. Madhusudan from Nature Conservation Foundation and Wild life Conservation Society who conducted the study, vehicle density was 50 per day in 2003, when traffic was allowed all the 24 hours. Now it has reached a massive 553 a day despite a 12 hour traffic ban.

Roads thrills but kills

Roads passing through Nagarhole Tiger Reserve in Karnataka

However, it was also found that large mammals like Sambar deer (Rusa unicolor) are not repelled by roads. This is due to the presence of grass and tender leaves in the road edges due to the routine clearance by the forest department, says the study.

The routine clearance along road edges creates micro habitats which attracts many herbivores, making them more prone to road kills. According to experts, this is the major reason why herbivores like Sambar deer, chital, mouse deer (Moschiola meminna), black naped hare (Lepus

nigricollis) and small Indian civet (Viverricula indica) becomes the top names in road kills near protected areas.

Better EIAs and measures

The findings of the study call for immediate measures to check over speeding on such roads which is a major reason for animal death from vehicle collision. It also demands effective implementation of scientifically designed animal crossing structures across such roads.

But above all, the need of the hour is to conduct long-term environment impact assessments even after completion of developmental initiatives to find out unforeseen impacts. If we hurry again under the false notion of development to become a global power, we may commit irreversible mistakes to the future generations by swiping away the remaining biodiversity of our nation.

Indian leopard (Panthera pardus fusca) at Nagarhole Tiger Reserve (Video)