I keep a small flock of 7 hens that free range around the orchard. There are a few issues with this, however, with pre-planning, they are a great addition. The hens love to scratch the mulch around the trees, and if you are like me and like to have mulch around the trees, and have it look nice, forget the chickens. They will spread that mulch out quicker and further than you can imagine. They also like to eat young fruits that they can reach. Ive had them roost in young trees and peck the fruit. Ducks or geese might be a better option for some situations.
One added bonus is that they will clean up the fruit that is thinned off in june drop as well as hand thinned.