Everyone present who has seen Sabine's Gull elsewhere said they typically associate with Bonaparte's Gulls. So when the above Bonaparte's landed in the water of the inlet and floated around for awhile, I thought this might be the Sabine's invitation. No luck, however.
The bird had been seen on Friday by James Fox and Karl Overman. James posted this photo of the Sabine's Gull from his Flickr site.
I had an afternoon commitment and so had to depart relatively early. When other Michigan birders who stayed on reported also not seeing the bird, I didn't feel so bad.