Bird strikes are killers! Since 1978, 35 USAF aircrewmen have died due to bird strike damage and crashes.
Driving in Delaware southeast of Dover a few years ago, I drove along a flock of snow geese that was LITERALLY 20 miles long....continuous stream of them.
The Air Force has done a lot of testing of aircraft components regarding birdstrikes. The test usually consisted of shooting a frozen chicken at about 300 f/s at radomes, canopies, and even engines when running (in a test stand of course). Even in a test setup, those frozen chickens do a lot of damage (frozen so that they would not "disassemble" shen being shot out of a compressed air cannon).
Also the AF has some strictly enforced regs regarding low level buzzing of wildlife refuge areas. Not just the usual green enviro reasons, it's a good way to lose a plane at worst, at least lose flight status.