by Shyamala Ratnayeke
Our remote cameras are made by TrailMaster and are designed to be anchored to trees. We usually mount our remote cameras on rebar so that we have some flexibility with regard to where we place the cameras. For example, some sites that seem good for a camera may have not suitable trees to tie the camera units to.
The camera, which is mounted on one side of a trail, is linked by cable to an infrared receiver that picks up an infrared beam from a transmitter on the other side of the trail. When an animal walks down the trail, it's body cuts the infrared beam, triggering a picture, after which the camera automatically reloads.
Picture 1: A TrailMaster camera mounted on rebar and protected by aluminium housing. The receiver (with similar a housing) is attached below. The infrared beam from the transmitter (not shown) is set at a height of about 6-8 inches from ground level. In this way the infrared beam is broken by the body of small carnivores such as mongooses, and the legs of larger animals such as elephants, buffalo, bear etc.
Elephants (and other animals, especially sloth bears) are curious and will often check out the camera. Both bears and elephants can damage the camera and infrared units beyond repair, which is why we have them encased in aluminium housing. The housing was designed and built by Tennessee Wildlife Resources Agency staff David Brandenburg and Rodney Woodson. The housing has saved the camera outfits innumerable times from bear and elephant abuse.
Picture 2: An elephant emerging from the jungle encounters the infrared transmitter and feels it out with his trunk. He left it undamaged, fortunately for us.
Picture 3: Despite all these precautions, a persistent elephant can occasionally do a number on a metal-housed camera.
About the author:Dr. Shyamala Ratnayeke is studying sloth bears and other carnivores in two Sri Lankan national parks.
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