I'm in Ohio and we have areas of alot of wild cherry trees. I don't know if they have much for actual fruits. I try to identify them because the wilted leaves can be toxic so I want to know if the sheep may ever be around them.
Have you considered doing some plant cages? Cages around the plants so the chickens can only eat as much as grows outside the cages, can't demolish it totally. Just a thought. If you could do like a row cover with wire to give an area time to establish.