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.”

When asked whether the birds will return or not as the temperature is expected to further plummet within a couple of days, he said chances are rare as once they leave their temporary habit in a season, they hardly return. They shift to some other place.

Dr Manish Vishwakarma, a renowned radiologist of Dhanbad who is also the president of Dhanbad Birders, said, “We have noticed that the number of Red Crested Pochard is significantly low and if the weather condition doesn’t improve as per speculation after January 15, almost all the birds will return from here.”

“Usually the migratory birds leave from Dhanbad during the last week of February or first week of March. But this year, it has started more than two months earlier due to sudden change in the climate and increase in temperature,” said Vishwakarma.

“We have plans to visit some other prominent places in the nearby areas like Tilaiya dam and also the favourite destinations of migratory birds in Bengal to carry out a study,” said Vishwakarma.

Established on September 14, Dhanbad Birders through an extensive survey has identified six places within the town which are hotspots of bird watching and has the presence of at least 20 species of birds.

The spots identified during the survey are Jagjivan Nagar, DS Colony (near Pampu Talab), Bartand (in the vicinity of CIMFR), Bekar Bandh, Bhelatand (near DPS Hirak Branch) and Bhelatand Village.

While seven other sites identified in the suburbs are Dhokra near Domerpur (17 km from Dhanbad), Govindpur (12 km from Dhanbad), Chhai Gadda near Kargali Ghat in Baliapur (20 km from Dhanbad), Domgarh Boating Point (23 km from Dhanbad), Maheshpur in Katras (23 km from Dhanbad), Aamtal (6.2 km from Dhanbad), Foothills of Dhangi Pahar in Pradhan Khanta (14 km from Dhanbad).