Really? Crows?

Why can grenades go off, Molotov explode, and outright firefights can go off within feet of the crows....even bullets crack and wiz over their heads and they will continue undisturbed but when I walk next to them they freak out and "call a hoard". Like a fucking grenade can go off and no one hears that, but crows make so much noise everyone hears? Who in God's name came up with that??