Atarian7

First you need to find out if the cat is afraid of shadows.

Are groundhogs typically aggressive when they're attacked? Many cats don't even take the big rats, only smaller mice so perhaps a groundhog, a bisam, a beaver etc simply would be a much too large and strong pray for most housecats. A lynx, a cougar yes but that is not your typical cat.

My animals have learned not to mess with possums or the black cats with a white strip down their back. It's not fun waking up at 3am after the dog jumped into bed with you after being skunked.