Cassin's Vireo
Vireo cassinii
The vireo is 11–14 cm (4–6 inches) long. It has a grayish olive head, back, and flanks, with whitish underparts. One of its distinctive features is the solid white "spectacles" around its eyes, along with white wing bars. These markings set it apart from other similar species like the plumbeous vireo and the blue-headed vireo.
ID text from Wikipedia, CC BY-SA 4.0
Hutton's Vireo
Vireo huttoni
Hutton's vireo is 10 to 12 cm (3.9 to 4.7 in) long and weighs about 9 to 15 g (0.32 to 0.53 oz). The sexes have the same plumage. Adults of the nominate subspecies V. h. huttoni have an olive crown and nape, pale lores, a wide, broken, pale whitish eye-ring, and pale olive ear coverts. Their upperparts are olive that becomes greener on the rump. Their wing coverts are dusky olive with wide pale yellowish olive tips that show as two wing bars. Their remiges and rectrices are dusky brownish to blackish with pale yellowish olive edges on the outer webs. Voice: The song of Hutton's vireo is highly variable among individuals and populations. The general pattern is "a monotonous and unmusical series of nasal and wheezy 2-syllable, ascending phrases: zu-wee.....zu-wee.....zu-wee.....zu-wee.....". Some variations are "descending phrases: zee-ooo.....zee-ooo.....zee-ooo.....zee-ooo......", mixed "ascending and descending phrases in the same series: zu-wee....
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
Learn this pair in BeakBrain
Photo and call practice, free in any browser.
Play BeakBrainPhotos and recordings are credited to their authors under the licence shown. Full profiles: Cassin's Vireo and Hutton's Vireo.