This may be a bit of a tangent, but I think it is important to acknowledge the fact that an animal can be dead for quite some time before it stops showing "signs of life". Animals can and often will continue to do the "funky chicken" long after brain death. Some hunters continue to "kill" the animal during this stage.
This varies widely with species. A buddy of mine that I hunt with didn't quite get this until a couple seasons ago, and he's been hunting far longer than I have. I shoot a lot of snowshoe hares. Lots and lots and lots. I shoot them in the head with a .22WMR from distances of 5 yards to about 80 or so. On average, about 25-30 yards. A 30 grain .22WMR projectile going 2250fps carries 3x the energy of a typical .22LR projectile. When the .22WMR projectile connects with the head or neck of a snowshoe hare, the damage is emphatic. It would be similar to shooting a mule deer in the head with a .700 Nitro Express. Typically, the head of the hare is so traumatized that it partially falls apart or off the animal. Nevertheless, these animals perform all sorts of unnatural acrobatics, anywhere from 10 to 30 seconds after death. So anyway, my buddy witnessed me shoot a hare one evening, about 65-70 yards away. I shot it in the head and it started its last dance. To my surprise, my buddy started jogging down the road. I asked him what he was doing and he said "it's suffering man, I'm going to kill it". When he arrived at the hare, he stopped and looked confused. He had intended to shoot it in the head, but the head looked like the inside of a pumpkin. The hare was dead within a split second of me pulling the trigger, but to an observer (even a well-seasoned one) it was suffering. Granted, this guy never hunts hares.
Likewise, I can blow the head clean off a grouse with that .22WMR and the bird still take it's time to stop moving. In these situations, I do not continue to "kill" a dead animal.