Chickens are apparently confusing

We've recently started letting the chickens run free range for part of the day. Today was the first time that the yaks and the chickens were near each other, and the results were not what I was expecting. The little bantams (who are, of course, very bold) came right up to poor Grunt here, who decided they were Scary, and ran away. This brought Kate over, who also decided that Chikkinz Iz Scary, but she decided to charge the chicken who was challenging her. (He skittered away from her.) I tried to explain to the wee fluffy chickens that it is all fun and games until they get trampled by an angry yak, but, well...explaining things to chickens doesn't usually go very well. The whole flock seems determined to dig around right outside of the paddock and are having a fine time doing so, while the herd is pretty unsure what the heck these little things are or what they are doing. They've been in sight of each other the entire time, but now the chickens can get CLOSER. Terrifying!