VIENNA, Oct. 23 -- Climate change will lead to a sharp decline of common species of birds in Europe, ecologists attending a meeting on birdlife here warned on Thursday.

About 2.3 million breeding birds, such as the blackbirds, wrens, and chiffchaffs, could disappear in Germany alone by 2050 due to climate change, Thomas Gottschalk from the University of Applied Forest Sciences, who was here attending the BirdLife Fall Conference, told the Austria Press Agency in an interview.

However, there are also birds who will do well as a result of climate change, such as the great tit, the Eurasian jay, egrets, and rare types of bee-eaters, all of whom would see their numbers increase, he said.

Gottschalk said the most harmful factor to bird population is the intensification of land use, particularly in the agricultural sector, which has halved the number of farmland birds in Germany over the past 30 years.

Climate change could lead to a discrepancy between the beginning of breeding season and the time it takes for food sources to become adequate, said Erwin Nemeth from BirdLife Austria.

He took European pied flycatcher for example. The birds breed earlier in the year, but its food source, the caterpillar, is available increasingly later in the year. This could affect breeding success and lead to its population decline.

Additionally, the warming has led to avian diseases being spread north into Europe onto otherwise unaffected bird populations, and reserve areas for certain bird species may also need to be adjusted, he said.