A team from Karnataka has now come out with a scientific study on how roads passing through a forest affect wildlife. The study, carried out in the Nagarhole National Park, makes it clear that large animals don’t like coming anywhere close to the highway. Many are killed by vehicular traffic as well, reports Kalyan Ray
With India on the fast lane to development, an increasing area of forest land is being cleared to make space for man’s greed. More and more roads pass through our forests, and very little thought goes into how this infrastructure will impact wildlife.
Even though an environmental impact assessment is conducted before approval of projects in forest land, the assessments often are piecemeal rather than a holistic analysis of animal behavioural patterns and their impact on ecology in the long run.
Absence of scientific studies analysing the impact of road infrastructure on forests and its inhabitants perpetuates myths. Researchers from Karnataka have now come out with what they claim is the first scientific study on the impact of roads passing through a forest, on large-bodied animals like the elephant and the tiger. The study, carried out in Nagarhole National Park, makes it clear that large animals don’t like coming anywhere close to the highway and are pushed further deep inside the forest because of the roads. Many are killed by vehicular traffic as well.
The Mysore-Mananthavadi highway, which passes through a crucial wildlife corridor in the southern part of Nagarhole, was chosen for the study. The road, upgraded to a high speed road in 2009, is one of the five major public access roads passing through Nagarhole, posing one of the most important anthropogenic threats to a forest landscape that houses the highest number of tigers and elephants. Although vehicles on these highways often caused accidental deaths of wildlife, no studies on animal habitat use in the park have been carried out so far.
Two stretches; two sets of results
The researchers from Wildlife Conservation Society, Bangalore and Nature Conservation Foundation, Mysore selected a 19.1 km-stretch of the highway. It was studied in two different segments. In the first segment (7.4 km), vehicular traffic was prohibited for 34 months (with exceptions for park vehicles on patrol and public emergencies) after a diversion was created. On the other hand, vehicles continued to ply on the second segment (11.7 km) during the day. Both segments remain closed for 12 hours – from 6 pm to 6 am.
The team first estimated vehicle density on the road and surveyed animal trails intersecting the highway. Subsequently, they set up camera traps in 10 different locations and surveyed the area for eight months – between November 2009 and June 2010. They found 681 animal trails in the vicinity of the road and the density was 40 per cent higher in the first segment, suggesting greater use of road edges by large animals in a vehicle-free environment. The supporting evidence came from camera traps that recorded movement of nine species including seven large animals – elephant, gaur, sambhar, chital, wild pig, leopard and tiger.
“Our data strongly suggest an avoidance of busy stretches of highway by certain large mammals. Segment two, which had 23 times the vehicular traffic density compared to segment one had lower photo capture rates for chital, gaur and elephant,” the team reported in the April 10 issue of Current Science. Vehicular traffic on the highway was estimated at 50 per day in 2003. But it has now jumped to 553 per day. Admitting that for wild pigs, tigers and leopards, the difference in sighting in the two stretches was not discernable, researchers suggested sustained monitoring of the highway for a longer period to have a better assessment of animal response.
Road improvement and highway development projects, the team said, were being proposed within India’s protected area network, which formed mere four per cent of the country’s landscape. Although these roads enhance connectivity between key economic centres, the upgrading of minor roads to high-speed highways also pose a serious threat to wildlife and around protected areas.
The new study emphasises the need for continued environmental impact assessment of development projects to identify and mitigate unforeseen impacts. “The misuse of EIA should stop. For instance, a UK-based company that carried out the EIA for this road project did not take into account the impact on animal behaviour. It only factored in pollution,” team member Sanjay Gubbi from Wildlife Conservation Society told Deccan Herald.
Dandeli-Anshi forest
Nagarhole is not the only example of highways through reserve forest. There is also violation of EIA in Dandeli-Anshi forest in Karnataka. Between 2008 and 2011, the central government allocated almost Rs 65,000 crore in road development, triggering a rapid growth of motor vehicles, which in turn further intensified the demand for better roads.
The 2010 elephant task force set up by Union Environment Ministry recommended that EIA needed to incorporate insights on biodiversity, especially habitat connectivity and animal movement. The task force suggested setting up a National Elephant Conservation Authority within the 12th-Plan period with a seed budget of Rs 600 crore and one of the tasks of the authority would be habitat protection. According to the task force, India has an estimated 26,000 elephants in the wild and 3,500 elephants in captivity.
Gubbi said there are myths and popular notions – perpetuated by foresters and the common man alike – which further complicate elephant conservation tactics. One of the common perceptions is that jumbos prefer sugarcane and banana.
But in a separate study published in Biological Conservation, Gubbi showed finger millet (ragi), maize, cotton and paddy are liked most by elephants. The animals did not show any special affinity to sugarcane. Finger millet is the number one target possibly because of its sodium content and strong smell.
“Possibly elephants opportunistically raided sugarcane fields during their forays to finger millet, maize or paddy fields,” Gubbi said. Based on an assessment of crop-loss claims made by farmers around Nagarhole National Park, the study shows farmers retaliate against raiding elephants using live wire and gunfire that claimed lives of 33 pachyderms between January 2008 and May 2009.
During 2006-2009, the State government paid compensation worth almost Rs 26 lakh as damage to 1,955 incidents of crop loss. In the same period, elephants killed 10 persons and injured eight, because of which the State paid another Rs 19 lakh. “Land use around Nagarhole is changing at a large scale level due to several factors including infrastructure development leading to elephant habitat fragmentation. In the future, these changes can lead to higher conflict resulting in greater damage to farmers,” Gubbi said.