I have just fenced in a 2,000 square foot area and planted fruit trees and grape vines. I'm also going to put in blackberry bushes and some raised garden beds. As soon as the weather warms up a little I'm planning to add a small flock of about six chickens. I do not have any experience with poultry. Can I let the chickens roam freely through my garden or will they be destructive and eat all of the plants? Thank you for any advice.