I already wrote about horses and yawning once this week, but it bears repetition. Yawning is a displacement signal. It tells an aggressive herd member to take a chill pill and relax. There is no danger. Breathe, man, breathe.
Anna Blake has a great article on yawning as a calming signal here.
Oh, and you can probably tell that my experiments with colour are ongoing. Let me know what you think.