I don't know how I missed the mangey look to the neck, but I didn't notice this until I was looking at my photos. At 1st we were thinking this bird was molting OUT of breeding plumage, having dropped its ruff, but it now looks like a few of the ruff feathers are just starting to come in. Jeff Wilson was up there on 4/28, and got even better looks at the bird than we had. He saw several white elongated feathers coming in on the neck.
The large size and orange base of the bill should have made me think this bird was a male, but inexperience with the species had me calling it a Reeve until I got home and looked at my photos and checked out some references.