Last night, just after dusk, I was feeding the dog and spied the intruder across the yard.
A tabby cat was slinking his way through the bushes behind our Eglu, and he finally popped up, crouching right at the junction between the coop and the run. Although he was forty feet away, I could swear he was licking his chops. Luckily, the girls were already in the coop, so they didn't see him.
A sotto voce "Argus, look! get him!" was enough to send our Great Dane bounding across the yard toward the now-retreating cat. Before Argus could get within 10 feet of him, the cat had scampered up and over the ten-foot privacy fence between our yard and the neighbor behind us.
We'll see how long it is before he returns.
And here I thought we'd see a raccoon or opossum as our first intruder.