Possibly non-humane for something that size. I’m thinking .22 CB shorts would be the ticket.
You might not drop them on there on the spot — but they would die somewhere.
While stationed in Minot I hunted these rabbits which I discovered while duck hunting. At first I used .22 standard velocity but could not keep up with them. Since they run about a 100 yards and stand on their hind feet I switched to my 6.5 Rem Mag and waited till they stopped and stood up. They could kick the snot out of a beagle. I wouldn’t even bother with a pellet gun let alone target .22. Having them hang around a house would make it easier.