In the past seven years the Dutch Air Force has recorded 413 bird-plane collisions. Zoologist Dr. Hardenberg found a way to prevent bird accidents.

As long as any Dutchmen can remember, the airspace over their crowded lowlands has swarmed with birds. But the birds have increasing competition. Part of the sky over The Netherlands has been invaded by commercial air routes; another part has been taken over by the military. And the birds are…