Camera traps to track animals in mangroves

Prithvijit Mitra, TNN | Jan 16, 2012, 01.49AM IST KOLKATA: A team of WWF and Wildlife Institute of India (WII) officials will be moving into the Sunderbans to resume camera-trapping on January 20. Aimed at zeroing down on the number of big cats and other animals that roam the mangrove forest by filming them, the exercise has been planned on a grand scale this time, with the aid of satellite imaging. Cameras will be installed across a 1500sq km area, including the South 24-Parganas part of the forest, which has never had camera traps. The Sajnekhali tiger reserve area will also be covered. Ninety cameras, to be installed in pairs, will be used. WII and WWF have divided the forest into 16sq km grids. Each grid will have a pair of cameras. They will face each other for better and additional frames that will help to identify the animals being captured. The cameras run on battery and are fitted with heat and motion sensors. They switch on automatically when animals tread near them. "It's a difficult job for you can't walk in the Sunderbans. Also, the cameras need to can't be installed in places that just about anywhere. It should have a reasonable possibility of being crossed by animals. So, we are looking for relatively high ground to install them. For this, we shall consult the forest department staff and taking the help of satellite images from Jadavpur University's School of Oceanographic Studies," said Anurag Danda, head of climate adaptation and Sunderbans Landscape of WWF. Danda is among the six officials who will lead the survey. The camera traps have to be installed at a height of less than four feet to shoot the animals. Since they generate infra-red rays that turn the camera on whenever they hit an obstacle, they can't be installed at an angle. "In that case, the rays will hit the ground and switch the camera on. So we can't put them at a greater height that would have kept them out of the reach of animals," explained Danda. Several camera traps were damaged by animals when they had been installed in 2010. Explaining the utility of traps, director of Sunderbans Biosphere Reserve Pradip Vyas said, it helps to assess the movement and hence the density of tigers in a given area. "According to the census last year, Sunderbans has between 65 and 90 tigers. This figure may not be accurate. Camera traps give you a better idea about tiger movements and the ecology of the forest. We expect them to lead to a more accurate figure. This time we are covering a far bigger area that will give us a better picture," he said. Pugmarks and scat collection - the two other methods that are commonly employed - can never provide a correct figure in Sunderbans due to the impenetrable nature of the forest, according to experts. "Since the cameras have to be placed above the high-tide level, they may not be able to capture a sufficiently high number of tigers. In Sunderbans, big cats move around in low-tide levels, on muddy ground where cameras can't be used. But they should give us an idea about the minimum number of tigers in a particular area," said Pranabesh Sanyal, former director of Sunderbans Tiger Reserve. Thirty pairs of traps will be installed in Sajnekhali and South 24-Parganas each. The WWF and WWI teams will return to the spots to download photographs every 10 days. They won't remove the traps till a tiger has been filmed twice. "Recapturing is the essence of the exercise. It helps to know how frequently a tiger has been passing a particular area. This will give an idea about the density and movement of tigers in that particular zone, from which we can arrive at a projected figure," said Danda. Even though it usually takes three weeks to recapture an animal, it could take up to a month in the Sunderbans, said officials. Due to its hostile terrain and lack of dry ground, it could be taking tigers a longer time to cover an area. In order to make the exercise a fruitful oneand to hasten recaprturing, WWF officials have proposed the use of "cat lure" to draw tigers to the traps. "These are a foul-smelling substance that attract carnivores. It could help to raise the number pictures. But the forest department is yet to give us the permission," added Danda. http://timesofindia.indiatimes.com/city/kolkata/Camera-traps-to-track-animals-in-mangroves/articleshow/11504405.cms