I saw a great video on Facebook the other day of a llama (vicuna) chasing off a fox!
Check out Ashwood Llamas facebook page to see the video yourself.
Llamas do make good guard animals and can be used to guard sheep, chickens and other livestock.
However, be warned, not all llamas make good guard animals, females with young cria will be more interested in protecting the cria than anything else in the field.
Young male llamas in the natural environment would be the guard animals as the dominant male will have the females around him and the youngsters will head out to ward off the predator.
Ashwood llamas does have one male llama available that would make a good guard llama – Llancellot – check him out.