I mow fawns, yotes and ground hogs in fields all the time. No way can I stop the disc mower fast enough not to gobble them up and run them through the crimp rolls. Interestingly, when I go back to rake or ted the next day, they are always gone. The animal kingdom likes fresh killed (and processed meat). Same thing applies to when I go hunting. You don't leave a deer lying in a field or an elk or an antelope lying until the next day because it will be eaten. How it plays.
Cruel as it seems, I mow them and forget about them. I just provided a meal for a predator that they didn't have to hunt down and kill themselves.