Tuesday, April 10, 2012

Highways edging out wildlife


 Animals actively avoid roads and look for alternative paths while migrating from one place to another. That’s a major finding of the impact on vehicular traffic on the use of road edges by large mammals along a highway passing through Nagarahole forest reserve. 
    Animals’ preference for alternative routes reflected in lower encounter rates of chital, gaur and elephants at camera traps on the highway segment with high vehicular traffic density. The study was conducted on the 19.1-km stretch of the Mysore-Mananthavadi highway (MMH). This area forms the core of the largest global population of tigers and Asian elephants. MMH passes through a homogeneous area of forests in Nagarahole. Two segments in the same forest type, same rainfall regime and guided by the same management objectives were chosen for the study. 
    Data on vehicular activity (vehicle density per hour) were summarized in the two segments. In all, 681 animal trails intersected MMH. There was a greater use of road edges by animals in the nearly vehicle-free segment 1. 

    The figures strongly suggested certain large mammals avoided the highway. In segment 2 where vehicular traffic was 23 times of that in segment 1, the photo capture rates were lower for species like chital, gaur and elephants. The differences were not too remarkable for species like wild pig, tiger and leopard. 

    “The area of concern is that road improvement and highway development projects are now increasingly being proposed within India’s protected area (PA) network which is a mere 4% of the country’s landscape. Although these roads enhance connectivity between key economic centres, the upgrading of minor roads to high-speed highways poses a serious threat to wildlife in and around PAs,” said Sanjay Gubbi, member, state wildlife board, who headed the study team. 
    Although roads and other infrastructure are important for economic development, poor planning, disregard for ecological aspects and excessive road expansion into wildlife habitat will further fragment and destroy wildlife population and their habitats in the long term, the report observed. 
    During 2008-11, the Centre allocated $13.67 billion for development of roads, triggering an annual growth of 12% in motor vehicles which further intensified the demand for good roads. The five major public access roads passing through tiger reserves pose a big threat to herbivore species including chital, gaur and sambar that graze along highway edges. These species are most susceptible to roadkill. 

    THE WAYS OUT Wherever possible, develop alternative road alignments to permanently avoid high-speed traffic in protected areas Stop vehicular traffic at night when wildlife is most susceptible to roadkill Install speed-deterrent measures, like road humps, and scientifically designed species-specific and topography-specific structures like underpasses, overpasses and overbridges


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