I agree with KC. They are probably my favourite vireo, though I find it tough to get decent photos of them. Yours, however, are great!
I was thinking that oo although Vireo's are not my strong point visually.I hate to be a wet blanket, but I'm not sure if Cassin's Vireo can be ruled out. Sure, it does seem rather bright for a Cassin's, but they can be quite bright, especially when in fresh basic plumage. The two species are extremely similar (I believe the Solitary Vireo complex to be underrated, identification wise), and there is some overlap and intergrades. Lastly, Blue-headed would be very unusual in Nevada, so the bird should be very closely studied. To quote Mr. Sibley:
The three species in the Solitary Vireo complex are rather poorly differentiated... intermediate birds (and perhaps hybrids) should be expected, and not every individual will be identifiable.
Neil
There's been more votes for Blue-headed than Cassin's, so I've uploaded all the pics of the Vireo to a new gallery for those who wanted to see more. Both birds are new to me, so I luck out either way. ;-)
"That said, your pictures look fine for Cassin's, and the ones in full sun especially impart a Cassin's feel to them. On the other hand, if this bird was to be seen in the east, it would be identified as a Blue-headed without much thought probably"
You see, a total mess.
JanJ