Let it be said - I cheer on over-protective mothers. If Frasier was in a mud nest packed with a little dog hair, I'd dive bomb anything that walked underneath. But as much as I admired the swallows' devotion, I never got used to small projectiles whizzing at my head like kamikaze pilots. (Watch for the fly-by at the 11 second mark.)
Thankfully, the little ones have flown the nest (there were six across our property) and I can now walk across the driveway without swearing.