When identifying vireos a good idea is to check the "spectacles." Most species has a white or light version of the eyering connected over the beak or lores. This Plumbeous vireo was hunting through the Narrowleaf Cottonwood for insects and stopped to have a quick look at us looking at him. This used to be a split species called the Solitary Vireo but "splitters" separated the bird into three species. They included the Cassin's vireo, Blue-headed and our Plumbeous.