Black-throated Blue Warbler

SCIENTIFIC NAME: Setophaga caerulescens

 Black-throated Blue Warbler

The Black-throated Blue Warbler is a small striking warbler and uniquely colored, with males and females having different plumages that they look as two different species.

They are small, well-proportioned birds with sharp, pointed bills.  Both sexes measure about 4.3 – 5.1 inches in length, with a wingspan of 7.5 – 7.9 inches and weight of 8 – 12 grams.

Males are dark blue on head and upperparts, with black face, throat, sides of the breast and flanks, contrasting with gleaming white center of breast and lower underparts and conspicuous white patch at base of primaries.

Females have a rather dull dark grayish- olive green above and buffy-yellow below with conspicuous whitish surpercilium, a broken whitish eye ring, and a whitish patch at base of primaries.

Immatures are similar to adults. Back and head feathers of males are edged with green, undersides are tinged yellow, and has some white tips to black feathers on throat.

Young females are like adults, more yellowish and sometimes without white spot on wing. 

CALL: A weak “sep”, and a single sharp “dit”.

SONG: A lazy, wheezy “zweea-zweea- zweea-zwee”, with the last note ascending, or a slower “zur-zurr-zree”.

Feeds on fruits, seeds, nectar and tree sap, especially in winter.

They eat insects such as moths, caterpillars, aphids, beetles and flies in summer.

Breeds in deciduous and mixed woodlands with shrubby undergrowth, and also in mountain laurel thickets.

Winters in dense tropical forests. In migration, it’s found in forests, forest edges, parks and gardens.

Breeds from SO Ontario and NE Minnesota, eastward to Nova Scotia, southward through New England, New York, and Pennsylvania, and in mountains southward to N Georgia.

Winters in Bahamas, Greater Antilles and the Caribbean Coast of Yucatan to Honduras.

The female builds a bulky, open cup- shaped nest made of strips of bark, dead leaves and moss, held together with spider web and saliva.

She lays 2 - 5 creamy white eggs, with dark speckles, and incubates them for 12 - 13 days.



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