Surprisingly, the number of migratory birds visiting the famous Chilika Lake in particular and the State in general has substantially gone down this winter.

Although one third of this year's winter has passed, the remarkable fall in the number of the winged guests has worried wildlife experts, environmentalists and ornithologists.

The best time for migratory birds is from October to February though all the local species are sighted throughout the year.

As is widely known these winged guests are generally seen in places of Chilika, Bhitarkanika, Hirakud and surrounding areas of Nandankanan.

All the divisional forest offices excluding Chilika even though they do not count their numbers, maintain that over a couple of years the migratory birds' number has significantly fallen with this year recording around 60 per cent fall.

Similarly, the divisional forest office at Chilika as part of its every year counting of winter guests holds a significant drop in the numbers so far recording only 2, 60,000 birds with additional 14 per cent expected this winter.

According to the statistics available with the Chief Conservator of Forests (Wildlife) and Chief Wildlife Warden, in 2002 the migratory birds' number was 12 lakh, in 2003 11.34 lakh, in 2004 it was 10.56 lakh and the last year it was approximately 9.58 lakh.

India has over 1,200 of about 8,650 species of birds found in the world. This figure rises to about 2,100 including the sub-species.

This abundance of species and sub-species is attributed to the variety of habitat and climate, which promotes continuous plant growth and insect activity providing abundant food for the birds. A total of 173 species, including 92 migratory and local migratory and 35 resident species have been spotted so far in Chilika, forest official source said. Spread over 1,100 sq km, Chilika is Asia's largest brackish water lake and home to thousands of resident birds.

During winter it receives a large number of winged guests from northern hemisphere places like Siberia and Mongolia as the birds used to migrate owing to the austerities of cold and food scarcity.

Moreover, Chilika's saline water supports an abundance of algae and plankton that are great favourites of the migratory birds. A vivid and colourful array of pelicans, ducks, geese, flamingos, storks, egrets, cormorants, eagles, plovers, sandpipers, herons, gulls and kingfishers flock to the Nalabana Bird Sanctuary, which is one of the best places to view birds in Chilika.

Citing the reasons behind the fall of migratory birds over the years, experts opined the foremost reason is the present era global warming that has brought a major seasonal change across the globe. The second reason is the rising degeneration of eco-systems preventing water bodies and natural habitats from easy foodstuff growth.

Chhainy, a renowned zoology teacher in Utkal University said, "Large-scale deforestation, rising mining operation and rampant fishing activities in and around Chilika are the reasons for damaged eco-systems that prohibit large scale migration of foreign birds."

Deputy Director, Nandankanan, AC Dinakar cited a seasonal change with less degree of coldness in northern hemisphere due to global warming may well be attributed as the best reason for the fall.

Moreover, poaching activities of the locals despite tight security by the forest department may be another cause, forest officials said. Notwithstanding the reasons, the issue is likely to attract worldwide attention because Chilka is a wetland of international importance and is a 'Ramsar Site.' Even the World Wildlife Fund describes Chilka as one of the hot spots of bio-diversity in India.