I'm not going to beat around the bush, the hills in my pastures are filled with birdshot, buckshot, .22 etc. All from dogs chasing my horses and chickens. Best thing to do with the kittens is to grab them when they are still young, just old enough to ween and take them to the local sale barn in a box and mark them free in front of the door.
To expand on the aforementioned dog issue, First came a warning to the owner, then .410 rocksalt, then 410 birdshot, then came the rifle. Just because you can't keep your pets home doesn't mean my chickens should feed them or horses and cattle entertain them. By law I can walk up to the threshold of the neighbors house and shoot his dog if I have proof it is disturbing my livestock.
On another note, my aunt and uncle had a feline over population problem but they never lasted long thru the fall they would get under the hood of his truck. We'll just say a 3rd gen cummins still started with a couple cats in the belt where it's nice and cozy. Used to get prolly 3 a week that way.