At Michele's recommendation I ran home to get Duke, my extremely senior Great Dane, to help me herd them up. Duke has yet to learn to ignore the barn animals, so I spent the run back to the field explaining how gentle he had to be. Yes, I talk to my dog, and it helped take my mind off the fact that the animals were in the field unprotected (and Elsie had been taken in broad daylight, so my fears aren't unfounded). And he was AWESOME! He moved out and stretched the leash as far as it could go so we converged on the sheep almost like experienced shepherds! My concern was that we not spook the sheep, who were accustomed to the furtive darting of border collies and who were going to be getting a laid back guardian dog any day now - I didn't want them to have a fear of big dogs in their presence. He was a natural - he was alert and intent without being vocal of pulling on the leash. The sheep finally decided he was serious about them moving up to the barn, and they ran up. The alpacas were easier to convince - perhaps they had watched the sheep and decided to follow suit.
It was a pretty great exercise, and a huge relief - plus I was only 10 minutes late opening the kennel!