Located along Kerala-Tamil Nadu Border, Chinnar Wildlife Sanctuary has a unique landscape with an even more interesting ecosystem. Falling under the rain shadow region, it is home to a diverse mix of flora and fauna, which includes an extensive collection of medicinal plants as well as the Sanctuary’s flagship species like the grizzled giant squirrel (Ratufa macroura) and the tufted gray langur (Semnopithecus priam).
But in recent years, there has been a steady dip in the once healthy population of both terrestrial as well as arboreal species in the region, owing to roadkills from the vehicles speeding on the state highway that runs through the Sanctuary for a stretch of 15 km.
Concerned at the surge in roadkills, the Sanctuary management tried different interventions to help animals reside peacefully without being fatally affected by human intrusion.
But before that, the officials of Kerala Forest Research Institute (KFRI) conducted a roadkill survey in Chinnar to corroborate their claims in 2013.
“We had calculated the average number of vehicles passing through the Sanctuary per month and per day for five months, which was 26,816, and 894, respectively. The survey reported over 85 roadkills, which was so shocking as it included some of the rare and endangered species like rusty spotted cat, leopard cat, slender loris, Indian porcupine, Jerdon’s Nightjar and brown fish owl,” shares PM Prabhu, the Assistant Wildlife Warden at Chinnar.
To resolve this crisis, the Sanctuary authorities installed 15 speed breakers at relevant locations despite facing opposition from local taxi drivers and even local politicians. This move, however, did little to alleviate the problem faced by the arboreal animals.
“The newly constructed speed breakers were serving a great role to rein in roadkills, especially for nocturnal (active at night) species, by controlling the speed of the vehicles in the Sanctuary. However, the problem persisted for diurnal (active during the day) arboreal animals, especially along the Chinnar-Marayoormain road, where the activities of high arboreal animals naturally occurred,” he explains.
After much deliberation, the Chinnar’s eco-development committee (EDC), forest department officials and local members of Chinnar’s and Alampetty’s tribal colonies, came up with the innovative solution of ‘canopy bridges’ for arboreal animals in 2017.
Prabhu explains how they constructed the bridges across 19 locations. “A systematic survey of the identification of locations and preparation of canopy bridge was carried out along the road to find out the exact location where the canopy bridge or rope overpass had to be erected. We found that many locations were frequently used by the arboreal animals to cross the road,” he explains.
Each species was observed separately, and the timing and frequency were also noted. Many exclusive locations catered to certain species and so the bridges were designed accordingly to accommodate the weight of the animals. In these areas, the team identified two trees on either side of the road to fix the canopy bride across the road at sufficient height.
Using high-quality nylon ropes as the external lining, the internal section was made using 1-1.5 m bamboo sticks tied with an iron twine.
“At Alampetty, we used fine mesh over the path to make them safe and more animal-friendly. Both ends of these two parallel ropes were connected to the nearest trees on both sides of the road to form an overpass bridge. All such bridges were made and installed by the Tribal trekkers EDC members of Chinnar and Alampetty with passion for animals,” Prabhu shares.
During the observation period, the authorities noticed that many members of the Tufted-gray Langur and Bonnet Macaque species were playing and shaking the canopy bridge while crossing.
Hence, the canopy bridges were prepared strong enough to overcome this issue. Also, modifications were made following frequent inspections by Prabhu and others.
As for the impact, Prabhu shares that besides providing a leeway for the arboreal animals from crossing tarred roads, these bridges have significantly brought down the roadkill mortality of these beings.
“The animals have also adapted quite well to the canopy bridges, whom we have observed using the bridge from day one. Bridging the fragmented canopy with the linear construction, these serve as a continuation of the natural tree canopy and have proved effective in conserving biodiversity, especially in areas with high wildlife movement,” he concludes.
Such issues are not just restricted to Chinnar but almost every natural reserves and wildlife sanctuaries across the country, where human intrusion through roadways have majorly affected the local wildlife. Solutions like canopy bridges, that can help India safeguard its wildlife effectively are not just economically feasible but are also easily implemented.
Here’s a video shot by Prabhu that showcases Chinnar Wildlife Sanctuary and its vibrant pack of animals, birds and tribal communities at its best.
(Edited by Saiqua Sultan)