Wilson's Warbler

I was at the harbor in Salton Sea SRA on Saturday and noticed a beautiful yellow bird flashing as it flitted about between small trees among large rocks above the harbor. It moved so fast that it was difficult to focus on and take photos. I described it to a couple that I thought were birders as a yellow bird with a black patch on the top of its head. I guessed it was a goldfinch of some sort. I got home and to my surprise my photos revealed a largely green bird with yellow on it. I realize that my identification skills need work. 

It is greenish above, yellow below, and has a long, thin tail. Males have a black crown patch that may be reduced or non-existent on the female. There are three subspecies of Wilson's warbler. Cardellina pusilla chryseola, the subspecies I saw, nests from southwestern coastal Canada to northern coastal California. It migrates to southern Baja California, Mexico and is declining because the resorts in that area are gobbling up its preferred habitat. It is a migratory bird at the Salton Sea. This subspecies is greener above and brighter than other subspecies and has a distinctive orange-tinged yellow forehead. 

This and the next two photos show the orangish tinge on the forehead. 

Although blurry, this is the best overall photo showing how green it is.