Killing a living being is easy from a distance, especially with poison but up close and personal without any danger is a different story. I've used a shovel on a gopher taking its head off. I've drowned gophers holding them under water.
I recall the fist bird I shot as a kid. The pellet took a bit of its shoulder off, couldn't fly and landed in the neighbors yard. Another sparrow kept flying down to it, must have been its mate. Found the remnants a few days later. A cat must have finished it off. Good memory to remind me never to kill without a cause!
I've taken that lesson to heart, it's become a part of me and who I am. I can and will kill when warranted but would much rather avoid it.
Killing squirrels in a cage would be difficult if thought about and I would not welcome doing so and the reason I avoided buying one of these years ago
Sometimes I can be gooey inside