I have no problem with killing pest animals. A pest can be any variety of species; really it's just an animal in a place it's not supposed to be and doing something it's not supposed to do. Sort of like how a weed can be any plant that you don't want growing in an area you dont want it. Dandelions are great but most people don't want them all over their lawn. It's the same thing with animals. Squirrels, chipmunks, raccoons, birds, etc are all cute until they leave their wild environment and start invading your cultivated spaces. I would probably try a hands off approach, the bird netting that you put over fruit trees for instance, and if they still found their way in then I would dispatch them with a pellet gun.