Llamas, when you don'texpect to see one, sure can startle you. A friend of my husbands from his army days raised until last year miniature horses too.
The first time we visited there, I of course had to look for the horses first and did a double take when a big llama came gallumping in attack mode towards me on a foggy day. Took a quick retreat over the fence.

I meant, the coyote sees the llama. New grand daughter in laws family farms and has a lot of rough ground unsuitable for farming and they have raised sheep for years on this as a pasture. Their guardian is a donkey. They have found mangled remains of a coyote in the pasture. They have to be careful when they want to move the sheep to have the donkey penned up where he can't attack the sheep dogs.

Lol, gandle, your son's theory is as good as any theory. I hope it works. I remember when we went to a national Zoo and one llama decided it did not like a lady and spit all over her. They are great spitters.

I did get a laugh from his theory, although it sure depends on traffic at the right moment.

Seriously, I've read that llamas are great for sheepherding, or at the least, sheep-guarding. It seems to be in their nature to protect and defend the flock. One guy reported that his llama would search for newborn lambs and stand over it until a human came to the rescue. It should be interesting to learn if that protectiveness extends to the horses. If so, a llama would be far more reliable than hoping for traffic at the appropriate moment.