This one looks mostly like a Glaucous-winged Gull, but the highly patterned wing coverts and pale fringes to the primaries seemed odd to me. Maybe some Herring Gull heritage? Several comments from friends in Oregon and California were that this bird is well within the large range of pure Glaucous-winged Gulls. Puerto Peñasco is simply a fantastic place for gulls – I heard that a Lesser Black-backed was here a couple days after us. There are multiple records of both of these here, yet only one of each for all of Arizona.
A nice vagrant trap in the desert is this little nursery at the sewage ponds. We had a flock of about 10 juncos here, including one Pink-sided and one Gray-headed among the Oregon Juncos.
Western Bluebird by our hotel, Viña del Mar. There weren't huge numbers around, but they could be found almost anywhere. They are present only once a decade, at most.
The rarest bird I found was this immature female Rusty Blackbird at the dump (note the plastic bag on the barb wire). The iris was gray, but narrow and hard to see well. The rufous highlights on the breast, head, back, and scapulars and especially the relatively sharp, thin bill separate it from Brewer's Blackbird. I think this photo also shows how the rump is contrastingly gray.
This Google Earth screen shot shows how barren the desert of this CBC circle is.