Blackburnian Warbler Range

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Blackburnian warblers are small passerines and average-sized wood-warblers. They measure around 11 to 13 cm (4. 3 to 5. 1 in) long, with a 20 to 22 cm (7. 9 to 8. 7 in) wingspan, and weigh 8 to 13 g (0. 28 to 0. 46 oz). The average mass of an adult bird is 9. 7 g (0. 34 oz), although is slightly higher in fall due to fat reserves, averaging 10. 2–10. 4 g (0. 36–0. 37 oz). Among standard measurements, the wing chord is 6. 3 to 7. 3 cm (2. 5 to 2. 9 in), the tail is 4. 2 to 5 cm (1. 7 to 2. 0 in), the bill is 0. 9 to 1 cm (0. 35 to 0. 39 in) and the tarsus is 1. 6 to 1. 8 cm (0. 63 to 0. 71 in). In summer, male Blackburnian warblers display dark gray backs and double white wing bars, with yellowish rumps and dark brown crowns. The underparts of these birds are white, and are tinged with yellow and streaked black. The head is strongly patterned in yellow and black, with a flaming-orange throat. It is the only North American warbler with this striking plumage. Other plumages, including the fall male and adult female, are washed-out versions of the summer male, and in particular lack the bright colors and strong head pattern. The Blackburnian warbler is practically unmistakable if seen well, even the female due her dull-yellow supercilium, contrasting with greyish cheeks and yellow throat contrasting with the dark streaky sides and back. The only other wood-warbler with an orange throat is the flame-throated warbler of Central America and is very distinctive, lacking the contrasting blackish streaking about the head and whitish underside of a male Blackburnian. Basic plumages show weaker yellows and gray in place of black in the breeding male. Blackburnian warblers' songs are a simple series of high swi notes, which often ascend in pitch. Transliterations have included zip zip zip zip zip zip zip zip, titititi tseeeeee or teetsa teetsa teetsa teetsa. Their call is a high sip. Genetic research has shown that their closed living relative is the bay-breasted warbler, the latter species perhaps specialized to forage in the same coniferous trees at lower levels. Hybridization in the wild has been recorded once each with a bay-breasted warbler (in West Virginia, with a black-and-white warbler (in Pennsylvania) and possibly a wintering hybrid with a Kirtland's warbler (in Hispaniola).