[He wishes he knew how to contact them, too, they seem to know things...but they seem to be elusive little devils.]

If the were created, then it must have been someone highly skilled. But no, there was more to the situation that gives evidence they are from another world.

[He looks over them, specifically the collars around each corgi's neck.]

Originally they weren't able to leave the tree that had been living in. Doing so would have killed them.