Bahama Oriole Icterus northropi
Version: 2.0 — Published July 16, 2020
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A tropical icterid that is mostly black with large yellow wing coverts, rump, and lower breast, and belly. Males and females are very similar in appearance, and it is difficult to tell sexes apart other than with techniques such as DNA testing (6, 3).
With its yellow and black plumage, the Bahama Oriole is distinctive and is unlikely to be confused with any other species on the Bahamas. Its appearance, however, closely resembles that of several other allopatric orioles of the Greater Antilles, which also have brightly contrasting yellow and black coloration, including Cuban Oriole (Icterus melanopsis), Puerto Rican Oriole (I. portoricensis), and Hispaniolan Oriole (I. dominicensis). Bahama Oriole adults differ from all of these taxa in their more extensively yellow underparts, with black being limited to the throat and breast.
Juvenile and Immature Plumage
Fledglings are dull olive, with dusky gray-brown wings and pale greenish-yellow wingbars. The underparts are lighter, and the throat and lower belly are tinged brighter yellow green.
In Juvenile Plumage, the upperparts are grayish brown; the feathers of the mantle with darker feather centers, creating a slightly scaled appearance. The remiges are gray brown, with whitish-yellow tips to the median and greater coverts forming two wingbars. The underparts are dull yellow, sometimes with a dusky wash on the lower throat and upper breast. The flanks, belly, vent, and uppertail coverts are brighter, approaching a dull lemon yellow. The lores are dusky black. The tail is a dusky olive-brown.
Young birds acquire progressively more black feathers on the lores, throat, breast, and head. Yearling Bahama Orioles have a black throat patch extending from the throat to the auriculars, and thus have delayed plumage maturation with cryptic plumage in their first breeding season.
Sexes similar; both have elaborate adult plumage, which is common in tropical orioles and likely the ancestral state for Icterus (9). Female perhaps slightly duller. Head, throat, upper breast, back, and scapulars deep black. Rump and uppertail coverts lemon yellow. Tail black, slightly duller than head, throat, and back. Lesser and median wing coverts lemon yellow. Greater coverts and remiges black, slightly duller than head, throat, and back. Lower breast, belly, tibial feathering, and undertail coverts lemon yellow.
Bahama Oriole likely follows a complex basic molt strategy. The first prebasic molt of juvenile Bahama Orioles produces produces a black throat patch, but is incomplete and some juvenile flight feathers are retained until the next prebasic molt. The only molt that occurs in adults is likely a complete prebasic molt in late summer; however, more data are needed on the precise timing of this molt (8).
Bill mostly black with blue-gray extending from the base of the lower mandible to around the middle of the bill (8).
Tarsi and Toes
From Garrido et al. (6).
Wing length: mean 92.5 mm ± 2.0 SD (range 90.5–95.5, n = 11).
Tail length: mean 86.2 mm ± 4.1 SD (range 77.5–91.0, n = 12).
Bill length (culmen): mean 19.9 SD ± 0.9 mm (range 18.3–21.2, n = 12).
Tarsus length: mean 24.5 mm ± 1.0 SD (range 23.1–26.3, n = 12).
Wing length: mean 98.4 mm ± 2.4 SD (range 93.5–102.0, n = 15).
Tail length: mean 91.6 mm ± 3.0 SD (range 87.0–98.0, n = 16).
Bill length (culmen): mean 20.5 mm ± 1.1 SD (range 18.9–23.4, n = 15).
Tarsus length: mean 25.3 mm ± 1.0 SD (range 23.6–27.5, n = 16).