birdfeeders
edyong | December 3, 2009In the forests of Germany live large numbers of blackcaps, a small species of songbird. They all look very similar, but they actually belong to two genetically distinct groups that are becoming more disparate with time. For the moment, the best way to tell them apart is to wait for winter. As the cold sets in, one group of blackcaps flies southwest to Spain, while a smaller group heads northwest towards Britain.
If the prospect of spending winter in Britain rather than Spain seems odd to you, you're not alone. Indeed, blackcaps were hardly ever ventured across these shores before the 1950s.…