Cuttack, Dec. 6: Delayed arrival of winter has affected the flight of migratory birds to Cuttack, particularly at Ansupa lake, a freshwater lake on the bank of the Mahanadi in Athgarh.

The missing winter chill has delayed the arrival of not only the migratory birds, but also of the Indian species.

Sources said the birds throng the Ansupa lake wetlands usually from the first week of December. But, that trend has been bucked this time.

"The climate is not favourable for the birds' arrival as temperatures have not registered a fall so far. The delayed winter might be the reason behind the birds' arrival being held up," said Cuttack divisional forest officer Sudarshan Behera.

Ornithologists attributed the sudden drop in the Ansupa lake water level to the delay in the birds' arrival.

The lake's water level rises after the Mahanadi river floods its system. Lack of adequate rainfall this year has also led to a drop in the water level, which might affect the eco-system that provides the ambience and food to the birds.

"Climate change is certainly a cause for concern; not just humans but a lot of species, including migratory birds, as they find it difficult to adapt to situations," said local resident Pravakar Sahu.

Official sources said 7,027 migratory birds were spotted at Ansupa lake out of 35,000 birds that arrived in Cuttack early in January this year.

A two-day census with detailed documentation and videography conducted in January 2015 spotted 6,000 small pratincoles near the lake. Official sources said the common migratory birds spotted in Cuttack were identified as red-crested pochard, cotton teal, brahmini duck and pintail. Besides, nearly 35 species of Indian birds were also found during the two-day census.

Official sources said around 12,000 birds of 20 species were sighted during the census in 2012, while the number rose to 15,000, including, 25 to 30 species in 2013 and 23,000 birds in 2014.

"We are hopeful that the inflow of migratory birds will start with the next 15 days as there has been a gradual drop in the temperatures across the state already," Behera said.

Senior forest officials said that a mid-winter bird census would be carried out in January next year to ascertain the exact number of birds at Ansupa in particular and Cuttack district as a whole.