Rabbits. They ate the bottom leaves off my two blueberries this summer too. Luckily, there were leaves that were too high for them that are fine. Try spraying the area around the bushes with a spray like Liquid Fence. It will work as long as the bunnies don't like the blueberries too much. If the bunnies persist then you'll need a fence.

Thanks. Mine are small enough I think I'll build a small wrap of chicken wire to try and protect them until they get larger. We do have a lot of rabbits around.