If the animal is on your property and it is not supposed to be then it is not cruel to kill it, in my opinion. My birds are the same as my bogs, and are looked at like family the same as my wife and kids which mean I will protect them from any threat. Having issues with them in the past is the reason they die on my property. I give them a chance to stay off the property if not that's there choice. It doesn't make me cruel it makes me not weak hearted. What's cruel is letting a animal you have takin responsibility for die because of negligence