My cat is a birdkiller who likes to bring me mangled, half dead birbs. I feel bad leaving them on the porch to die but the alternative is letting my cat finish them off slowly. Is there a way to minimize the bird’s pain?

glumshoe:

The solution is keeping your cat indoors.

Keep your cat inside. 

If the situation comes up again, this sounds gruesome, but take a brick, place the bird’s head on a flat surface, and crush the skull as quickly as possible. No intact brain means it’s a painless death. Works on all animals small enough to crush the skull like that.