In fact, some birds may be evolving shorter wings to let them navigate traffic more safely.

Well, the most surprising thing was that the wing length on these road kill birds was longer than on a sample of birds that had died accidentally in mist nets. And we think that these net fatalities probably represent a sample of the population at large. So when we compared the road kills with the population at large, we found that the road kills had significantly longer wings.

Evolution is the result of the tendency for some organisms to have better reproductive success than others -- natural selection.