The number of migrating birds in Bulgaria has declined by over 50% in the last 12 years, according to environmentalists.

Data of the Bulgarian Society for Protection of Birds shows that 312 000 birds spend the winter in Bulgaria in 2009-2010.

This is 390 000 fewer compared to the 1997 numbers, and 10 000 fewer than in 2008-2009, Yordan Hristov from the BSPB has announced.

In his words, this drop is evidence for the effects of the global warming as many of the migrating bird species that came to Bulgaria, now spend the winter in countries to the north because Bulgaria has become too warm for them.

Over 150 volunteers of the BSPB took part in the annual count of migrating birds in January, encompassing 200 sites around the country. The court was part of the Mediterranean counting of migrating birds, which has been taking place every year since 1967, and is coordinated by Wetlands International.

Hristov has pointed out the importance of bird migration patterns with respect to the evidence for the global warming.

He has stressed some regional differences that seem to have resulted from the global warming as well. In the past 20% of all migrating birds in Bulgaria were located around the Danube River, whereas now their number has dropped to 4%.