This was an unexpected find. I recorded sporadic Ring-billed Gull calls from 12 midnight through 4 AM on 3-1-07. Recorded a few more calls on night of 3-10. None of the subsequent calls were as near to my house as the above example. Cannot find anything on the internet regarding nocturnal migration of RBGUs. Nearest possible roosting lake is almost 2.5 miles away. Too far to be picked up by my recording apparatus.