There were 2,000 vultures in Bharatpur's Keoladeo National Park during the 1980s. In 1998 experts could spot only four . Ornithologist Asad Rahmani fears that the vulture is disappearing throughout India. To find out the reason for this decline, the Centre for Science and Environment sent its toxicologist Amit Nair to collect carcass samples -- food for the vulture -- from the park. They had high levels of chemical pesticides. Like vultures, humans are also at the end of the food chain. The pesticide threat is very real to humans as well. Down To Earth analyses