Blue-headed Vireo
Vireo solitarius
The blue-headed vireo has similar plumage year round and does not drastically change its appearance during the breeding season. It can be characterized by its olive green upper body, two bold yellow wing bars down the edge of its wing, and a deep blue-grey crown from which it gets its name. The juvenile plumage of immature blue-headed vireos is not distinct but very similar to the adult plumage. Voice: The primary song of the blue-headed vireo is a simple, slow, monotonous tune that is often confused with the faster red-eyed vireo (Vireo olivaceus) song. The primary song is sung only by the males and usually only during the breeding season. The males become quite vocal during the breeding season, with the song frequency reaching its height prior to mating and then decreasing after copulation.
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
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