So, do rats know the snake is a threat? The mice don't seem to.
As far as pre-killing goes, I can't do it. If it came down to rat or snake and I had to make a grab or a knock to the head, I have no doubt that I could and would. But I really don't think I have it in me to pre-kill the rats with premeditation. I don't think it's wrong, I just don't think I could do it. If I try live rats and I can't get comfortable, I'll go to f/t. But I find that even grosser than live for some reason!