Weather for the birds

Photo: Guido Gerding, Creative Commons 3.0

Friday, December 22, is technically the first winter day here in the Northern Hemisphere. But looking out of the window in Prague, one would hardly guess it's nearly Christmas time. Daytime temperatures are well above zero degrees Celsius, there's no sign of snow whatsoever, and plants have become so confused that some have started to blossom again. Owing to the unseasonably warm weather, we can still see species of birds around that should have left Central Europe weeks ago.

Photo: Guido Gerding,  Creative Commons 3.0
A number of migratory species were so puzzled by the warm weather that many of the birds simply forgot to fly south this autumn. Jaroslav Cepak from the National Museum's Bird-Ringing Station is a specialist on migratory birds.

"Some of the species that migrate for short distances, to the Mediterranean, for example, have stayed here in larger numbers than usual. They can be observed even now in December and it seems they have decided to spend the winter here. It is especially the case with water birds that are staying on water bodies that have not frozen over. For example, greylag geese and lapwings are still here in large numbers."

Photo: Richard Bartz,  Creative Commons 2.5
Ornithologists estimate that dozens or hundreds of birds at most from each species have broken the pattern this year so if the weather should change suddenly their population would not be affected. Besides, the warm weather did not affect birds like swallows that leave for Africa in mid-September because they follow different criteria than daytime temperatures.

Photo: CTK
Several species of northern birds arrive every year in the Czech Republic which is their wintering grounds but they, too, are behind schedule this year.

"The numbers are very low because the warm weather has prevailed also in the north, in Scandinavia, for example. Rivers are not frozen over, so the birds have access to food and have no reason to fly south. Those are bean geese, white-fronted geese. The goosanders which usually spend winters here on the Vltava have not arrived yet. Rooks that arrive around October 20th were also late this year and in the city their number is low but they may still be scattered outside in the fields."

Jaroslav Cepak says gradual changes in the migration patterns of birds can be observed across Europe but it is still early days to draw any definitive conclusions from that.