Human interaction is changing the blackcap (Image: FLPA/Neil Bowman)

The friendly bird-feeder could be an evolutionary force to be reckoned with. British people who feed birds are contributing to the evolution of a whole new species of blackcap, new research suggests.

Martin Schaefer at the University of Freiburg in Germany and colleagues measured genetic variation between blackcaps in two German sites 800 kilometres apart just after the birds had returned from their winter grounds on the Iberian peninsula and in the UK, respectively.

Both groups return annually to the same forest in Germany, where they live for six months of …