Those are definitely not the kind of dogs I have seen herding sheep in the Rockies. I am sure that if two of those were after my hide I would be scampering up a tree. But I doubt that I would set them off in the first place. Beautiful dogs BTW.
I’ve walked by Great Pyrenees sheepdogs a few times. ...even petted some the neighbors’ dogs, when the neighbors weren’t around. One would have to frighten the sheep pretty badly to get those dogs to bite people, as far as I know.
The herders are probably border collies.