My unrepentant serial killer of a feline absolutely decimates the ground squirrel population on our property (and if we're talking literally, "decimates" might not even do it justice). Luckily, she has little to no interest in song birds (and they are even tougher and larger than the rodents in my area), so I don't feel too bad about the environmental impact of letting her roam the area.

My compassion for the wildlife generally ends at the footprint of my house, especially when the mice and voles are getting into our pantry every goddamn fall and spring.