Delivering newspapers, I've hit birds and run over rabbits, squirrels, and possums. I'm not slamming on my brakes, but I also don't try to do it. I feel bad when it happens, but if I try to swerve, I may still hit it, plus lose control of the car. I've stopped when I've seen turtles, and help them along their way. You can miss what looks like a rock moving really slow, and it's easier to just straddle one of them then stop. No chance it's going to dart out of the way.
My wife ran over an already run over skunk. That car that usually stayed in the garage stayed outside for a bit. I ne