In the warm months food will be ok but winter maybe a problem, they would live but barely. I buy 80lb bags of feed and always have a bin filled, I would ration it big time, also drying out greens would help. we have no weeds in most of my yard as we grow mint an that chokes out the weeds,but the mint is fed to our rabbits though chickens don't really like it I bet they would eat it if they were hungry enough. We use a leaf compost pile in thier run and add rabbit litter, this is a great food source as they get bugs and sprouts, I get great soil in return