The forest department has for the first time launched a comprehensive and scientific survey of birds in Chhattisgarh's Kanger Valley National Park, which is home to the state bird ‘hill mynah’, an official said on Saturday.The three-day exercise, involving 56 experts from 11 states of the country, was kicked off from Friday in Kanger Valley, located around 300 km away from capital Raipur in the Maoist-hit Bastar district.