I've had free range chickens around my barnyard for years. They navigate through all the stalls, manure pile, and paddock area. They are TERRIFIC fly deterents! At one time we had over 30+ chickens wandering around and rarely had a chicken/horse accident (but it does happen). That was my INITIAL reason to have chickens, since with ten horses, we get a lot of flies, the eggs were just a bonus!
Most of our problems were mamas taking chicks into the stallion's stall. He LOVES the chickens (plays with them sometimes), but trying not to step on twenty some chicks is a daunting task for even the most chicken-loving stallion! The mamas seemed to know they were 'safe' in his stall from nighttime predators and slept in varying corners at night with their broods.
The other issue, is, of course, predators. We rarely lose anything to air predators, between all the ground cover and larger animals, but have been targeted by fox big time the last two years. Finally had to come to terms with either discontinue free ranging or periodically irradiate predators by whatever means is effective. (We do put the girls in at night now with a workable number of 17 ... but when we had 30+ I didn't even KNOW where half of them were.)
