Gnatcatcher, vireo, or warbler (?). Only got this one shot and I'm undecided, but I do agree with Pierre & Tom, the bill isn't like most vireos.
Mostly gray on top; tan-to-white underneath, narrow white eye ring; narrow black pointed bill. In this dead tree that was on the edge of the Virgin River.
Nikon Z 6II
,NIKKOR Z 70-200mm f/2.8 VR S 1/640s f/16.0 at 300mm iso450
Free Crop of DX Image ReSized for Internet Viewing
full exif