Source: CBC News
Posted: 12/06/09 8:39AM
Putting out a bird feeder in the winter can have a dramatic effect on the evolution of migratory birds, researchers in Germany and Canada say.
In research published in Current Biology, scientists say a single population of European blackcaps has in a matter of decades split into groups that don't interbreed, despite living in the same forest for part of the year.
Bird researchers first noticed the divide in migratory patterns in 1959, after humans began offering the blackcaps food in the winter. One group migrates from Germany to the southwest, spending winters in Spain, while the other flies to the northwest to winter in Great Britain.
The two groups now show different adaptations based on the length of their migratory route and the food available to them in winter, the scientists said.
"The new northwest migratory route is shorter, and those birds feed on food provided by humans instead of fruits as the birds that migrate southwest do," said Martin Schaefer of the University of Freiburg.