I was looking for a California Gull in with the regular Ring-billed Gulls. I found a gull the same size as the ring-billed, with yellow legs and red on the bill. But the back was not the gray it should be for a California. It was a lot darker. So I took a picture and found some other birders to discuss it with. They said they noticed the darker, blacker back, but that they still thought it was a California. I did not agree and asked them to send their pictures around for confirmation. We all sent pics to various people and they agreed this was a lesser black-backed gull. The photo I will attach is mine, and not very good.

But Robert Winslow will load his photos on ebird and they are make it clear. Please let me know if you need to have him send the photos directly to you or if the ebird list photos work. 

California - wrong color back.

Western - not enough white on ends of feathers. 

St Pierre to look at Robert Winlow's photos. 

My (only so-so) photo was sent to Mark Holmgren and he called it Lesser Black-backed from that photo. 

I also used a Seabirds of the World book and Sibley.