And here's probably the best photo I've taken of a Mexican Yellow so far. At least it's the only Mex Yellow pic I took that I was able to ID myself. That's worth something.
Warblers can be a bit confusing, but the ones that frequent the oasis during migration are getting easier for me. Sometimes a fleeting look is all you get too, which doesn't help. I got lots of good looks at this one, and in spite of the funky looking eye-ring, it's a Nashville Warbler.
Here's a more diagnostic angle of the same bird, where you can better see the full eye-ring.
Then, here's a similar warbler that doesn't always clearly show its broken eye-ring. It's a MacGillivray's Warbler. Ah, the joys of birding! I'm sure without the aid of digital photography I would have given up by now.