| Black-throated gray warbler | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Parulidae |
| Genus: | Setophaga |
| Species: | S. nigrescens |
| Binomial name | |
| Setophaga nigrescens (Townsend, 1837) | |
 | |
Breeding range Winter range | |
| Synonyms[2] | |
Sylvia nigrescensTownsend, 1837 | |
Theblack-throated gray warbler orblack-throated grey warbler (Setophaga nigrescens) is apasserine bird of theNew World warbler family Parulidae. It is 13 cm (5.1 in) long and has gray and white plumage with black markings. The male has the bold black throat of its name, and black stripes on its head, as well as black streaks on its flanks; the female is a paler version of the male, with a white throat and less distinct black markings on the flanks and wings. It breeds in western North America fromBritish Columbia toNew Mexico, and winters in Mexico and the southwestern United States. The habitats it prefers are coniferous andmixed forests and scrubland, especially those withpinyon pines,junipers,sagebrush, andoaks. Its nest is an open cup of plant fibers lined with feathers, built a few metres from the ground in the branches of a tree or shrub. Three to five eggs are laid, and young are fed by both parents. Common in its breeding range, it does not seem to be seriously threatened by human activities, unlike many migratory warblers.
The black-throated gray warbler was first described byJohn Kirk Townsend from a specimen collected near today'sPortland, Oregon.[3] It was known to theChinook inhabitants of the northwest coast, who called itAh Kah a qual.[4][5] Townsend described the species asSylvia nigrescens, placing it with the other New World warblers and the unrelatedOld World warblers in the genusSylvia.[3][6] It is now placed in the genusSetophaga along with about thirty other species, after having been classified inDendroica for some time.[7] Within its genus, it is part of a group with black throats and yellow face markings that includes thehermit warbler andTownsend's warbler.[8][6] It is usually considered anearly offshoot among this group of species,[8][6] but genetic studies suggest a close relation toGrace's warbler.[9]
Of these relatives, the range of the black-throated gray warbler overlaps with those of Townsend's warbler and the hermit warbler, but they occur in different habitats. While Townsend's and hermit warblers commonly hybridize with each other, records of either species hybridizing with the black-throated gray warbler are uncommon.[10][11]
There are twosubspecies, which are highly similar and of dubious validity. Thenominate subspeciesS. n. nigrescens occurs on the Pacific coastal region from British Columbia to northern California, whileS. n. halseii, described by Giraud in 1841, occupies the inland parts of its range.S. n. halseii birds are slightly larger and more gray in their upperparts.[8][12]
The black-throated gray warbler has mostly black, gray, and white plumage,[8] which is soft, lacking gloss.[4] With its striping and the small yellow spot between its eye and bill, it is a distinctive bird. The sexes differ slightly, both having gray upperparts with black streaks, and white underparts with black streaks on the flanks.[8] The adult male is striped with black on the crown, throat, and below the eye, and has white around its chin and above its eye. The adult female has more dingy plumage on its head, with a white throat and dark gray cheeks.[8] The most similar birds to the black-throated gray warbler are theblack-and-white andblackpoll warblers, which although marked in black have entirely different plumage patterns.[8]
It is typically 13 cm (5.1 in) long, weighing 8.4 g (0.30 oz). Wing lengths are 5.6–6.9 cm (2.2–2.7 in), tail lengths 4.7–5.5 cm (1.9–2.2 in), bill lengths 8.4–9.6 mm (0.33–0.38 in), andtarsus lengths 1.66–1.88 cm (0.65–0.74 in), with females slightly smaller than males.[8][13] Wingspan ranges from 7.5–7.8 in (19–19.7 cm).[14]
This bird gives a sharptup orthick call, like that ofTownsend's warbler but flat and unmusical, as well as a highseeflight call. The male's song is a series of buzzy notes, with the earlier notes doubled and the next to last note high.[8] This song has three variations, including a quiet "soft song" given by the males while following females gathering material for a nest.[15]
The black-throated gray warbler breeds in western North America, its range extending from southwesternBritish Columbia along the Pacific coast to northernBaja California, and east to New Mexico and southern Montana. It winters mostly in Mexico, from southernBaja California toOaxaca state.[8][5][6] It has spread into parts of Wyoming and Montana only recently, asJuniperus osteosperma has expanded its range due to a warming climate.[16]Vagrants have been recorded across eastern North America[13] and inCuba.[17]
The black-throated gray warbler breeds in openconiferous andmixed forest with a brushy understory, in dry open oak forests, and inchaparral and other scrubland.[8][5] It is particularly associated withpinyon pines,junipers, and oaks.[5] It migrates to the south late in the fall, returning north in mid-spring.[4][5] While migrating, it forages in any woodland or scrub it passes through. In its wintering grounds, it occurs in dry woodland and tall scrub.[8] Though its status is not well known, it does not appear to be seriously threatened byhabitat destruction or other human activities, unlike many migratory warblers.[13][5][18] It is a fairly common bird,[5] among the most common in some localities.[19] Because it is common and not in rapid decline, it is assessed asLeast Concern on theIUCN Red List.[1][5]
The black-throated gray warbler is usually approachable, and can easily be observed while foraging. Despite this, it is poorly known, especially in its breeding behavior, of whichBirds of North America said "almost no information is available".[5] It forages, often in flocks with other species. It feeds on insectsgleaned on low branches, especiallycaterpillars.[20]
The nest is usually placed on a horizontal tree branch or in a shrub, a few metres above the ground. The nest is an open cup constructed of grass stalks and other fibres, and lined with feathers and hair. The female lays three to five pinkish eggs with brown dots from May to July.[8][21][22][23] Incubation and fledging periods are unknown. This species has been recorded giving adistraction display, pretending to be injured to distract predators from its nest.[24] Both parents feed the young, though the female may do so more frequently.[25]
