Villagers who feed birds in their gardens through the winter are increasingly likely to have a blackcap visiting them. This small (great tit size) insect-eating warbler has evolved as a summer visitor to Northern Europe over hundreds of thousands of years, spending its winters in the warmth of countries bordering the Mediterranean.
But as our climate has begun to warm over the last fifty years, and as feeding garden birds has become widespread in the UK, many blackcaps breeding in Germany are changing their migration habit. Instead of migrating to the warm south in the autumn, many fly west to winter here in southern England. Those that survive the winter - and many now do, thanks to our well-stocked garden feeders - have a shorter journey back to their breeding grounds in the spring than individuals who wintered in the Mediterranean sunshine. So they arrive there first, to claim the best breeding territories and raise the fittest young. Their young are then likely to be genetically programmed to spend winter here! So, in (a very long) time, it is possible the two populations will eventually split and the ‘English’ blackcap may become a new species.
So look out for a greyish-brown bird a little smaller than a sparrow. The males have an obvious black ‘cap’ and the females have an obvious brown one.
Evolution is happening before your very eyes!
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