For this year's annual census, the National Nark officials will be using camera trappings instead of the pugmark tracking technique
For this year's annual census, the National Nark officials will be using camera trappings instead of the pugmark tracking technique
While every summer, a census of animals living in the Sanjay Gandhi National Park (SGNP) in Borivali is conducted using 'pugmark tracking', this year is going to be different. Sometime in May, cameras that will run on solar energy, like the ones used in the recent all-India tiger census, will be set up in SGNP. 
Here's what an image captured through the Camera Trapping Technique
looks like. This is a Sunda clouded leopard photographed by an automated
camera-trap set up by the Conservation of Carnivores in Tangkulap
Forest Reserve on Sabah, Borneo in Malaysia. Pic/u00a0AFP Photo
Although officials refused to disclose the number of cameras that are expected to be put up, and the estimated cost of the exercise, according to sources, the cameras will be fixed at locations that are close to artificial lakes and ponds in the park. During summer, when waterholes in the forest dry up, wild animals are known to turn up at these water bodies.
Why it is better?
While the pugmark tracking technique has been widely used in India, it is considered faulty. It involves making of plaster casts of pugmarks, which are then analysed separately. According to experts, it is often difficult to differentiate between pugmarks of two animals from the same species, and the size of the pugmarks vary according to the ground surface.
But when cameras are used, one can easily make out differences between two tigers because each tiger bears stripes differ from another.
An official from SGNP on condition of anonymity said, "From past experience of using the pugmark technique, we have learnt that it is not accurate. Cameras using on solar energy will be fixed at various locations in the forest."
According to Forest Officer (Conservation) Anil Toradmal, the benefits of using cameras are many. He offers the example of the Tadoba Tiger Reserve and the Shahayadri Tiger Reserve in Maharashtra, where camera trapping has resulted in the collection of reliable data.
"The camera trapping method is better than the pugmark technique since we are able to easily tell the difference between two animals of the same species, and we learn from pictures collected, if the animal is injured or ill."
Krishna Tiwari from the Bombay Natural History Society (BNHS), who has studied leopards in the SGNP and recently shot a documentary along with a National Geographic channel team on leopards at the park, is happy with SNGP's decision. "We will able to learn more about various species that inhabit the park. Last year, when we shot the documentary using the camera trapping method, it not only gave us fantastic pictures of leopards, we were also able to spot other species. Such a technique helps us conduct a detailed study of animals and the photographs collected can also be used later for research," he said.
How does it work?
A camera is placed at a height of 1.5 to 2 feet on a tree, and using infrared technology, the camera captures a picture of the animal that comes in its range.
There are two fairly common types of cameras used. One uses active infrared technology. An emitter placed on one side of a trail sends out a beam of infrared light, which can't be seen by people or animals. An infrared detector is placed on the other side of the trail. When a passing animal breaks the infrared beam, a camera, which has been hidden along the trail and focused on the point where the animal will break the light beam, takes a picture.u00a0 Often, a pair of cameras is used to photograph both sides of the animal.
In the other type of system, known as passive infrared, the camera is linked to a detector that is constantly scanning the surroundings for sources of infrared wavelengths.u00a0 Warm-bodied animals emit infrared as the heat from the animal's body radiates out into the environment. Passive infrared cameras are rigged to take a picture whenever a moving source of heat is detected within the scanned area.
Those who live at SGNP
The park is home to a number of endangered species of flora and fauna. The forest area of the park houses over 1,000 plant species, 251 species of migratory, land and water birds, 5,000 species of insects and 40 species of mammals. In addition, it also provides shelter to 38 species of reptiles, nine species of amphibians and 150 species of butterflies apart from a large variety of fish.
The forest cover in the park helps provide the ideal habitat for wild animals. Chital, Rhesus Macaque and Bonnet Macaque are some of the wild mammals that can easily be spotted roaming inside the park. Other large mammals found in the park include Black Naped or Indian Hare, Muntjacu00a0 (Barking Deer), Porcupine, Asian Palm Civet , Chevrotain (Mouse Deer), Hanuman or Gray Langur, Indian Flying-fox, Sambar Deer and leopard. Reptiles living here include crocodiles, pythons, cobras,lizards,Russell'su00a0 Vipers, Bamboo Pit Viper and Ceylonese Cat Snakes.
How camera trapping works
A camera-trap is triggered by the presence of animals. However, the trap is used only to capture unobtrusive photographs instead of the animal itself. A camera-trap consists of three basic parts: a camera, a heat/motion sensor, and a power supply. 
The camera-trap is a box about a foot (30 cm) tall, six inches (15 cm) wide, and two inches (5 cm) thick. It is mounted on a tree facing outward to observe the surrounding forest. All day and all night long, an electronic eye looks for heat in motion. When an animal passes in front of the trap, the camera detects its movement and body heat, and quietly snaps a photograph. With the camera-traps one can take one minute videos after the photograph.
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