Robin, I had a chance to listen to some audio tapes of the calls of Raven, American and Fish Crows and after listening, and based soley on this one set of tapes, I think the bird we heard was indeed a Northern Raven. Nothing else makes that deep resonant "cronking" sound. But as I said, this was based only on the Peterson audio tapes. Rick Sussman Ashton,MD Warblerick@aol.com