Himachal Pradesh’s wildlife department has successfully tracked its radio-collared birds to Mongolia, the Caspian Sea, Bangladesh and Siberia, marking a major breakthrough in its pilot project to study the behavior and migration pattern of birds that visit the Pong Dam Lake. Four out of 12 birds that had been fitted with the radio collar at Pong Dam have returned to the lake, while one bird, which had been tracked to Tamil Nadu a few days back is now visiting Chilka Lake in Orissa.