I hate crows, house sparrows, cow birds and blue jays.....
I have a bird house on the side of my house that for the past two years chickadees have been nesting in it. Last summer I watched as four fledglings finally left the house. Early in the afternoon I saw a blue jay with its head far into the bird house until I scared it away and I never gave it much thought since I thought all the babies had successfully left.
Three days later when I went out to clean out the bird house, I found a fifth baby dead with it's eye pecked out. It was that damn blue jay.......
Since then, I shoot them whenever I can when they're on the ground under my bird feeder......
House sparrows frequently do murder to get another pair out of a good nesting spot. They make nice pets, though; I’ve reared several that fell out of the next still naked.