Blue-grey Gnatcatcher
Polioptila caerulea
It is 10–13 cm (3.9–5.1 in) in length, 6.3 in (16 cm) in wingspan, and weighing only 5–7 g (0.18–0.25 oz). Adult males are blue-gray on the upperparts with white underparts, slender dark bill, and a long black tail edged in white. Females are less blue, while juveniles are greenish-gray. Both sexes have a white eye ring. Voice: The songs (and calls) are often heard on breeding grounds, (usually away from nest) and occasionally heard other times of the year. Calls: "zkreee, zkreee, zkreee", Songs: "szpree zpree spreeeeey spree spre sprzrreeeee"
ID text from Wikipedia, CC BY-SA 4.0
Tropical Gnatcatcher
Polioptila plumbea
The adult tropical gnatcatcher is 10 to 12 cm (3.9–4.7 in) long, and weighs 6 to 8 g (0.21–0.28 oz). Its "jizz" is similar to that of other gnatcatchers; a small bird with a relatively long thin bill, a long frequently cocked tail, grey upperparts and whitish underparts. The central rectrices are black, while the outer are white (consequently, the tail appears primarily black from above, white from below), and there is a white patch in the wing (caused by broad white edging to the tertials).
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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