Drake & duck were crossing a busy road earlier when a 4x4 driven by youths ran the duck over & carried on motoring. The drake was flapping over the duck & a young woman picked up the duck & pulled its neck, then binned it.
Kindest thing to do in this case. Worst thing I had was a deer that had been hit by a car and its back legs smashed and was trying to crawl up a bank one night about 11 pm. I put it in my car and phoned the emergency vet (RSPCA wouldn't come out - no surprise there then)
poor thing was screaming in pain. Vet eventually arrived after one hour and put it to sleep. Had I known it was going to take so long I would probably have tried to kill it by running it over as I had no other means of putting it out of its misery.
I feel terrible when I hit stuff with my car. I'm just enough of a heathen to apologize to its spirit. Fortunately I haven't had to stop and put something out of its misery.