Donkeys are mischievous, Lulu and Fanny love to come up to Red when he is working, and try to get him to move or jump. They try to startle him, coming up behind him and sniffing his coat or bumping into him. This happens frequently, Red never moves or bats an eye, and he never gets startled or gets up. I do not know many creatures, canine or human, who would stay that focused on their work while a 400-pound donkeys is creeping up on them, sniffing their back and rubbing against their body. Rose used to jump out of her skin when they did that to her.
Red does not seem to notice, he is granite out there. Sometimes I think the donkeys are just jealous, they want to herd the sheep too, but it is more likely that they are just trying to stir up trouble, as donkeys will do.