With the sudden rise in temperature since the first week of January, the number of migratory birds has started dwindling in Coal Town. Red Crested Pochard, a large diving duck whose favourite habitat is lowland marshes, can be seen here in large numbers. But this year, more than 90% of them have left town. Similarly, Ruddy Shelduck, a distinctive waterfowl, are also decreasing in number. While speaking to The Telegraph Online on Monday, AK Sahay (62), a retired banker who also heads the Coal Town bird lovers association, Dhanbad Birders, said: “More than 90% of Red Crested Pochard have already left Dhanbad since the last week. While a large number of Ruddy Shelduck has also returned to their respective places.”