Bhubaneswar, Jan. 11: Scanty rainfall and fluctuating temperatures have led to a decline in the number of migratory bird species in the state this winter.

However, the number of the winged guests has increased this winter, according to the results of bird estimation at five places, including the Chilika lagoon. The most alarming part of the result, however, was the decline in birds visiting the Mahanadi delta.

According to the census report, more than 4.6 lakh birds of 161 species arrived at the Chilika this year, while more than 3.9 lakh birds of 77 species arrived at Nalabana. Though the number of birds visiting the lake has gone up by more than 90,000 as compared to last year, the number of species has come down by 11. There is a similar decline of 14 bird species at the Nalabana sanctuary as compared to last year. The lake, however received eight new species this year.

But, the decline of migratory bird species to the Mahanadi delta has emerged as a major concern for forest officials. While 28,663 birds belonging to 109 species had thronged the delta last winter, the number of species has come down to 63 this winter.

Principal chief conservator of forests (wildlife) S.S. Srivastava said most of the water bodies have dried up because of poor rainfall, which might be a reason behind the decline of bird species. "We would conduct a further study with the help of Bombay Natural History Society to ascertain the possible reasons," said Srivastava.

Bird lovers, on the other hand, attributed the decline to the increase in pollution levels in water bodies. "Oil spills from boats cause pollution. Besides, there is a dearth of food for migratory birds. In the Mahandai delta, we have been demanding a 10km radius of Bhitrakanika to be declared as eco-sensitive zone," said Monalisa Bhujabal, secretary of Wild Orissa, an organisation working for the conservation of birds.

This year, Bhitarkanika witnessed a decline in bird number. The report revealed more than 81,000 birds of 87 species, around 3,000 less than 2015. The number of species has come down to 87 as compared to last winter's 96.

TheHirakud Dam reservoir, however, witnessed the arrival of a record number of migratory birds this year. The census, which was conducted on Saturday, recorded the arrival of 95,912 birds of 60 species at the reservoir this year. The number is 37,000 more than last year.

ADDITIONAL REPORTING BY SUBRAT MOHANTY FROM SAMBALPUR