Bridging the fragmented forests
Due to the Dhaka-Sylhet railway and Srimangal-Bhanugach road running through the reserve forest of Lawachhara, many of the critically endangered species have died in accidents while crossing them.
Data collected between 2015 and 2017 show 14 primates died while crossing the road in Satchhari forest, and 13 died in the same manner in Lawachara.
The same situation prevailed at Satchhari National Park.
This raised alarm among researchers as many of the mammals, including Phayre's leaf monkey, capped langur and slow loris, that died were either vulnerable or endangered.
It was the casualties that gave birth to the idea of an artificial aerial rope bridge connecting the two sides of the forest.
At least six canopy bridges were set up at different points in Satchhari forest connecting the two sides that have been created by man-made interventions, while five were built in Lawachhara.
Wildlife researchers and conservationists Hassan Al-Razi Chayan and Marjan Maria hired help at Tk 1,500 a day (for a few days) to set up aerial rope bridges and connect two fragmented sides of Satchhari forest in November 2020 -- the first of its kind in the country.
Following their footsteps, canopy bridges were constructed by a team of researchers from Jagannath University throughout the Lawachara forest in September 2021.
A NEED FOR BETTER CAMERAS
The teams also set up camera traps to monitor whether any of the intended animals actually used their bridges.
After analysing the photos sent by the cameras set at the bridges in Satchhari forest, researchers said thousands of animals, including various species of monkeys, slow loris and squirrels, have crossed the structures since its inception.
Official data suggest that there were 12 deaths per year on an average due to road accidents before the construction of the aerial bridges. But no monkeys or other endangered species were reported dead after those became operational.
There are seven species of monkeys in Satchhara.
Apart from these apes and Assamese monkeys, all other species of monkeys have come and gone through the bridges, said the authorities.
However, researchers say it will take more time for an ape to use such a bridge as they are careful species.
Marjan Maria, chief researcher of the canopy project in Satchhari, said, "The project is a success. We got expected results."
Meanwhile, nothing meaningful could be retrieved from the pictures stored in the cameras of Lawachhara canopy bridges due to poor quality.
"Due to poor quality, we could not get good quality pictures or identify the animals," said Habibun Nahar, an associate professor in the Department of Zoology at Jagannath University, who was involved in the project.
She said her team has obtained clear images of only two primates and some squirrels crossing the bridge. The researcher believes the number of species crossing is way more than what has been recorded by the cameras.
"Since there is no record, it is difficult to say for sure," she noted.
Her team has asked the forest department for high quality cameras.
According to a 2019 survey, there are 40 to 41 primates in Lawachhara National Park. Rezaul Karim Chowdhury, divisional forest officer, said, "Animals, including monkeys are using the canopy in Satchhari. The cameras are recording their movement clearly."
About the researchers request for better cameras at Lawachhara, he said he will look into the issue.