Black-throated Gray Warbler

Black-throated Gray Warbler
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Parulidae
Genus:	Dendroica
Species:	D. nigrescens
Binomial name
Dendroica nigrescens (Townsend, 1837)
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

The Black-throated Gray Warbler (Dendroica nigrescens) is a songbird of the New World warbler family. It is 13 cm (5 in) long and has black, grey, and white plumage. It breeds in western North America from British Columbia to New Mexico, and winters in Mexico and the southwestern United States. Common in its forest habitats, it does not seem to be seriously threatened by human activities, unlike many migratory warblers.

Description

The Black-throated Gray Warbler has mostly black, gray, and white plumage,^[3] 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.^[3] The adult male is striped on its head, with a black crown, throat, and stripe below the eye, and 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.^[3] The most similar birds to the Black-throated Gray Warbler are the Black-and-white and Blackpoll Warblers, which although black have entirely different patterns.^[3]

It is typically 13 cm (5 in) long, weighing 8.4 g (0.29 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 cm (3.3–3.8 in), and tarsus lengths 1.66–1.88 cm (0.65–0.74 in), with females slightly smaller than males.^[3][5]

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.^[3] This song has three variations, including a quiet "soft song" given by the males while following females gathering material for a nest.^[6]

Taxonomy

The Black-throated Grey Warbler was first described by John Kirk Townsend from a specimen collected near today's Portland, Oregon. It was known to the Chinook inhabitants of the northwest coast, who called it Ah Kah a qual.^[4][7] Townsend described the species as Sylvia nigrescens, placing it with the other New World warlblers and the unrelated Old World warblers in the genus Sylvia. It is now placed in the genus Dendroica, along with about thirty other species.^[8] Within this genus, it is part of a group with black throats and yellow face markings that includes the Hermit Warbler and Townsend's Warbler.^[3][8] Among these species, it is usually considered an early offshoot,^[3][8] but genetic studies suggest a close relation to Grace's Warbler.^[9]

Of these relatives, Townsend's Warbler and the Hermit Warbler overlap with the Black-throated Gray Warbler, but inhabit different habitats. While these two species hybridize commonly, records of hybridization 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 D. n. nigrescens occurs on the Pacific coastal region from British Columbia to northern California, while D. n. halseii, described by Giraud in 1841, occupies the remainder of its range. D. n. halseii birds are slightly larger and more gray in their upperparts.^[3][12]

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, and east to New Mexico and southern Montana. It winters mostly in Mexico, from southern Baja California to Oaxaca state.^[3][7][8] It has spread into parts of Wyoming and Montana only recently, as Juniperus osteosperma has expanded its range due to a warming climate.^[13] Vagrants have been recorded across eastern North America.^[5] It breeds in open coniferous and mixed forest with a brushy understory, in dry open oak forests, and in chaparral and other scrubland.^[3][7] It is particularly associated with pinyon pines, junipers, and oaks.^[7] It migrates to the south late in the fall, returning north in mid-spring.^[4][7] While migrating, it forages in any woodland or scrub it passes through. In its wintering grounds, it occurs in dry woodland and tall scrub.^[3] 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.^[5][7][14] It is a fairly common bird,^[7] among the most common in some localities.^[15] Because of its commonality, it is assessed as Least Concern on the IUCN Red List.^[1][7]

Behaviour

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 behaviour, of which Birds of North America said "almost no information is available".^[7] It forages, often in flocks with other species. It feeds on insects gleaned on low branches, especially caterpillars.^[16]

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 3–5 pinkish eggs with brown dots from May to July.^{[3][17][18][19]} Incubation and fledgeing periods are not recorded. It has been recorded giving a distraction display, pretending to be injured to distract predators from its nest.^[20] Both parents feed the young, though the female may do so more frequently.^[21]

References

1. ^ ^{a b} BirdLife International (2009). "Dendroica nigrescens". IUCN Red List of Threatened Species. Version 2010.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/149800. 
2. ^ Coues 1878, pp. 263–267
3. ^ ^{a b c d e f g h i j k l m} Curson, Quinn & Beadle 1994, pp. 126–128
4. ^ ^{a b c} Audubon & Macgillivray 1849, pp. 57–59
5. ^ ^{a b c} Sibley 2000, p. 437
6. ^ Morrison, Michael L.; and Hardy, John William (1983). "Vocalizations of the Black-throated Gray Warbler" (PDF). The Wilson Bulletin 95 (4): 643–647. http://elibrary.unm.edu/sora/Wilson/v095n04/p0640-p0643.pdf. 
7. ^ ^{a b c d e f g h i} Guzy, Michael J., and Lowther, Peter E. (1997). "Black-throated Gray Warbler (Dendroica nigrescens)". In Poole, A.. The Birds of North America Online. http://bna.birds.cornell.edu/bna/species/319. Retrieved 29 April 2010. 
8. ^ ^{a b c d} American Ornithologists' Union 1983, pp. 539–551
9. ^ Rabosky, Daniel L.; and 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. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2603228. 
10. ^ Rohwer, Sievert (1994). "Two New Hybrid Dendroica Warblers and New Methodology for Inferring Parental Species". The Auk 111 (2). http://elibrary.unm.edu/sora/Auk/v111n02/p0441-p0449.pdf. 
11. ^ Rohwer, Sievert; Wood, Christopher; and 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. ISSN 0010-5422. JSTOR 1369809. http://elibrary.unm.edu/sora/Condor/files/issues/v102n03/p0713-p0718.pdf. 
12. ^ "Dendroica nigrescens". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=178896. Retrieved 29 April 2010. 
13. ^ Hendricks, Paul (2004). "First nesting record of black-throated gray warbler (Dendroica nigrescens) for Montana" (PDF). Western North American Naturalist 64 (4): 548–540. https://ojs.lib.byu.edu/ojs/index.php/wnan/article/viewPDFInterstitial/1402/1257. 
14. ^ Garret, Kimball L.; Dunning, John B., Jr. (2001). "Wood-Warblers". In Elphick, Chris; Dunning, John B. Jr.; Sibley, David Allen. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf. pp. 492–509. ISBN 978-1-4000-4386-6. 
15. ^ Remsen, J. V., Jr.; Cardiff, Stephen (1979). "First records of the race scotti of the Rufous-crowned Sparrow in California". Western Birds 10 (1): 45–46. http://elibrary.unm.edu/sora/wb/v10n01/p0045-p0046.pdf. 
16. ^ Sprunt, Alexander, Jr. (1979). "Black-throated Gray Warbler". In Sprunt, Alexander, Jr.; and Griscom, Ludlow. The Warblers of North America (Revised and updated ed.). Doubleday. ISBN 0-385-12353-1. 
17. ^ Finley 1908, p. 127
18. ^ Wheelock 1912, pp. 401–404
19. ^ 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. 
20. ^ Grinnell & Storer 1924, pp. 529–531
21. ^ Finley, William L. (1923). "Black-throated Gray Warbler". In Pearson, T. Gilbert. Birds of America. 3. http://www.biodiversitylibrary.org/page/7824882#216. 

Works cited

• American Ornithologists' Union (1983). Check-list of North American Birds (7th ed.). Washington, D.C.: American Ornithologists' Union. ISBN 1-891276-00-X. http://www.aou.org/checklist/north/print.php. 
• Audubon, John James; Macgillivray, William (1849). Ornithological biography, or An account of the habits of the birds of the United States of America: accompanied by descriptions of the objects represented in the work entitled The birds of America, and interspersed with delineations of American scenery and manners. V. Edinburgh: Judah Dobson, A. Black. http://digital.library.pitt.edu/cgi-bin/t/text/pageviewer-idx?c=darltext;idno=31735056284767;seq=101;cc=darltext;view=image;page=root;size=s;frm=frameset;. 
• Coues, Eliot (1878). Birds of the Colorado Valley: A Repository of Scientific and Popular Information Concerning North American Ornithology, Part First, Passeres to Laniidae. United States Geological and Geographical Survey of the Territories, Miscellaneous Publications—No. 11. Washington: Government Printing Office. http://www.biodiversitylibrary.org/page/22626526. 
• Curson, Jon; Quinn, David; Beadle, David (1994). Warblers of the Americas: an Identification Guide. Boston: Houghton Mifflin. ISBN 0-395-70998-9. 
• Finley, William Lovell (1908). American Birds, Studied and Photographed from Life. New York: Charles Scribner's Sons. http://www.biodiversitylibrary.org/page/7277413#197. 
• Grinnell, Joseph; Storer, Tracy Irwin (1924). Animal life in the Yosemite; an account of the mammals, birds, reptiles, and amphibians in a cross-section of the Sierra Nevada. University of California Press. http://www.biodiversitylibrary.org/page/10786505#572. 
• Sibley, David Allen (2000). The Sibley Guide to Birds. New York: Alfred A. Knopf. ISBN 978-0-679-45122-8. 
• Wheelock, Irene Grosvenor (1912). Birds of California: an Introduction to More Than Three Hundred Common Birds of the State and Adjacent Islands, with a Supplementary List of Rare Migrants, Accidental Visitants, and Hypothetical Subspecies. Chicago: A. Ac. McClure. http://www.biodiversitylibrary.org/bibliography/7858. 

External links

• Black-throated Gray Warbler at All About Birds
• Black-throated Gray Warbler at the Internet Bird Collection