Black-throated gray warbler

The black-throated gray warbler or black-throated grey warbler (Setophaga nigrescens) is a passerine bird of the New 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 from British Columbia to New Mexico, and winters in Mexico and the southwestern United States. The habitats it prefers are coniferous and mixed forests and scrubland, especially those with pinyon pines, junipers, sagebrush, and oaks. 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.

Black-throated gray warbler
Male
Scientific classification
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 nigrescens Townsend, 1837
Vermivora nigrescens (Townsend, 1837) Bonaparte, 1838
Sylvicola nigrescens (Townsend, 1837) Audubon, 1839
Sylvia halseii Giraud, 1841
Mniotilta nigrescens (Townsend, 1837) Gray, 1848
Rhimanphus nigrescens (Townsend, 1837) Cabanis, 1850
Sylvicola nigricans Henry, 1855
Dendroica nigrescens (Townsend, 1837) Sclater, 1862

Taxonomy

The black-throated gray warbler was first described by John Kirk Townsend from a specimen collected near today's Portland, Oregon.[3] It was known to the Chinook inhabitants of the northwest coast, who called it Ah Kah a qual.[4][5] Townsend described the species as Sylvia nigrescens, placing it with the other New World warblers and the unrelated Old World warblers in the genus Sylvia.[3][6] It is now placed in the genus Setophaga along with about thirty other species, after having been classified in Dendroica for some time.[7] Within its genus, it is part of a group with black throats and yellow face markings that includes the hermit warbler and Townsend's warbler.[8][6] It is usually considered an early offshoot among this group of species,[8][6] but genetic studies suggest a close relation to Grace'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 two subspecies, which are highly similar and of dubious validity. The nominate subspecies S. n. nigrescens occurs on the Pacific coastal region from British Columbia to northern California, while S. 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]

Description
An illustration of a male

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 a 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 the black-and-white and blackpoll 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), and tarsus 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 sharp tup or thick call, like that of Townsend's warbler but flat and unmusical, as well as a high see flight 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]

Distribution and habitat
Second-year female

The black-throated gray warbler breeds in western North America, its range extending from southwestern British Columbia along the Pacific coast to northern Baja California, and east to New Mexico and southern Montana. It winters mostly in Mexico, from southern Baja California to Oaxaca state.[8][5][6] It has spread into parts of Wyoming and Montana only recently, as Juniperus osteosperma has expanded its range due to a warming climate.[16] Vagrants have been recorded across eastern North America[13] and in Cuba.[17]

The black-throated gray warbler breeds in open coniferous and mixed forest with a brushy understory, in dry open oak forests, and in chaparral and other scrubland.[8][5] It is particularly associated with pinyon 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 by habitat 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 as Least Concern on the IUCN Red List.[1][5]

Behavior

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 which Birds of North America said "almost no information is available".[5] It forages, often in flocks with other species. It feeds on insects gleaned on low branches, especially caterpillars.[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 a distraction 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]

References
  1. BirdLife International (2012). "Dendroica nigrescens". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.
  2. Coues 1878, pp. 263–267
  3. Townsend, John Kirk (1837). "Description of twelve new species of birds, chiefly from the vicinity of the Columbia River". Journal of the Academy of Natural Sciences of Philadelphia. 7: 187-192 [191].
  4. Audubon & Macgillivray 1849, pp. 57–59
  5. Guzy, Michael J. & Lowther, Peter E. (1997). Poole, A. (ed.). "Black-throated Gray Warbler (Dendroica nigrescens)". The Birds of North America Online. Retrieved 29 April 2010.
  6. American Ornithologists' Union 1983, pp. 539–551
  7. Chesser, R. Terry; Banks, Richard C.; Barker, F. Keith; Cicero, Carla; Dunn, Jon L.; Kratter, Andrew W.; Lovette, Irby J.; Rasmussen, Pamela C.; Remsen, J. V. Jr.; Rising, James D.; Stotz, Douglas F.; Winker, Kevin (2011). "Fifty-Second Supplement to the American Ornithologists' Union Check-List of North American Birds" (PDF). The Auk. 128 (3): 600–613. doi:10.1525/auk.2011.128.3.600.
  8. Curson, Quinn & Beadle 1994, pp. 126–128
  9. Rabosky, Daniel L.; Lovette, Irby J. (2008). "Density-dependent diversification in North American wood warblers". Proceedings of the Royal Society B. 275 (1649): 2363–71. doi:10.1098/rspb.2008.0630. PMC 2603228. PMID 18611849.
  10. Rohwer, Sievert (1994). "Two New Hybrid Dendroica Warblers and New Methodology for Inferring Parental Species" (PDF). The Auk. 111 (2): 441–449. doi:10.2307/4088607. JSTOR 4088607.
  11. Rohwer, Sievert; Wood, Christopher; Bermingham, Eldredge (2000). "A New Hybrid Warbler (Dendroica nigrescens × D. occidentalis) and Diagnosis of Similar D. townsendi × D. occidentalis Recombinants" (PDF). The Condor. 102 (3): 713–718. doi:10.1650/0010-5422(2000)102[0713:ANHWDN]2.0.CO;2. JSTOR 1369809.
  12. "Dendroica nigrescens". Integrated Taxonomic Information System. Retrieved 29 April 2010.
  13. Sibley 2000, p. 437
  14. "Black-throated Gray Warbler Identification, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2020-09-30.
  15. Morrison, Michael L.; Hardy, John William (1983). "Vocalizations of the Black-throated Gray Warbler" (PDF). The Wilson Bulletin. 95 (4): 643–647.
  16. Hendricks, Paul (2004). "First nesting record of black-throated gray warbler (Dendroica nigrescens) for Montana" (PDF). Western North American Naturalist. 64 (4): 548–550.
  17. Wallace, G. E.; Wallace, E. A. H.; Froehlich, D. R.; Walker, B.; Kirkconnell, A.; Torres, E. S.; Carlisle, H. A.; Machell, E. (1999). "Hermit Thrush and Black-throated Gray Warbler, new for Cuba, and other significant bird records from Cayo Coco and vicinity, Ciego de Avila Province, Cuba, 1995–1997" (PDF). Florida Field Naturalist. 27 (2): 37–51. Archived from the original (PDF) on 2015-09-24. Retrieved 2014-07-18.
  18. Garret, Kimball L.; Dunning, John B. Jr. (2001). "Wood-Warblers". In Elphick, Chris; Dunning, John B. Jr.; Sibley, David Allen (eds.). The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf. pp. 492–509. ISBN 978-1-4000-4386-6.
  19. Remsen, J. V. Jr.; Cardiff, Stephen (1979). "First records of the race scotti of the Rufous-crowned Sparrow in California" (PDF). Western Birds. 10 (1): 45–46.
  20. Sprunt, Alexander Jr. (1979). "Black-throated Gray Warbler". In Sprunt, Alexander Jr.; Griscom, Ludlow (eds.). The Warblers of North America (Revised and updated ed.). Doubleday. ISBN 978-0-385-12353-2.
  21. Finley 1908, p. 127
  22. Wheelock 1912, pp. 401–404
  23. Barlow, C. (1899). "The Nesting Haunts of the Black-throated Gray Warbler" . Bulletin of the Cooper Ornithological Club. 1 (5): 96–97. doi:10.2307/1360756. JSTOR 1360756.
  24. Grinnell & Storer 1924, pp. 529–531
  25. Finley, William L. (1923). "Black-throated Gray Warbler". In Pearson, T. Gilbert (ed.). Birds of America. 3.

Works cited
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