While some donkeys do make good guard animals in general, not all donkeys are good guards.
That said, I have a (and used to have more) guard donkey. BLM burro actually, and he is indeed a good guard. On my current farm it's only him and my horse together for now, with my chickens in a pen to themselves. But at my previous farm I kept chickens, ducks, and turkeys together and they had the run of most of the pastures and much of the barn, including the horse and donkey areas. My barn was an open layout and stall areas were separated by gates or open board fencing so the birds could come, go, and get away from any of the bigger animals at will.
In all the years only one chicken got stepped on by my horse, who is a known klutz so not surprising. My donkeys were and are always careful with their feet and because they are smaller it's easier for them to be careful. Whenever I had ducklings, poults, or chicks I made sure they could not access larger animal areas until momma had taught them how to navigate
such things around the smaller farm animals, or if raised in a brooder, big enough to be among the general bird population.
But again, not all donkeys are immediately good guard animals. Just like all llamas aren't nesseccarily good guards either. Had those too. One was good the other could have cared less.
