The First Sight Record of Blue-winged Warbler (Vermivora cyanoptera) in British Columbia. By Rick Toochin and Louis Haviland. Published: June 3, 2023.

The Blue-winged Warbler (Vermivora cyanoptera) is a small passerine that is found breeding in early- to mid-succession habitat patches of dense, herbaceous growth as well as of shrubs and some forest cover in the southeastern United States and parts of eastern Canada (Berger 1958, Confer and Knapp 1981, Will 1986, Buckelew and Hall 1994 Dunn and Garrett 1997). This species breeds from northern to southeastern Minnesota, central Wisconsin, central Lower Peninsula of Michigan, southern Ontario, north to south Georgian Bay, north-central New York State, south of Adirondack Mountains, central Vermont, central New Hampshire, and recently in extreme southern Maine (Curson et al. 1994, Dunn and Garrett 1997). The Blue-winged Warbler is a casual visitor but also a potential breeder in southern Quebec (Shaffer 1996). From Minnesota, breeds south through eastern and south-central Iowa and Missouri, although very local in northwest, to extreme northeastern Oklahoma, northern Arkansas, and Tennessee. From Maine, breeds south along Atlantic Coast to southern New Jersey, northernmost Delaware, northern Maryland, locally in southeastern Maryland, western Virginia, Tennessee, extreme southwestern North Carolina, northernmost Georgia, and the northern half of Alabama (Curson et al. 1994, Dunn and Garrett 1997, Sibley 2000). This species overall range is highly fragmented, and it is largely absent from the Mississippi lowlands of western Tennessee and western Kentucky, from mountains of eastern Tennessee, and eastern portion of West Virginia, and very local in western Virginia (Curson et al. 1994, Dunn and Garrett 1997, Sibley 2000).  The Blue-winged Warbler is also absent from heavily used agricultural portions of central Illinois, northern Indiana, and western Ohio, and from portions of central Pennsylvania (Curson et al. 1994, Dunn and Garrett 1997, Sibley 2000). The overall breeding range, and particularly the status of local populations, of the Blue-winged Warbler have changed markedly during the last century (Dunn and Garrett 1997).

 

The breeding range of the Blue-winged Warbler has historically gone through a northward expansion (Gill 1980). This species started showing range expansion northward along eastern seaboard in late 1800s (Gill 1980). This expansion followed major river valleys such as the Delaware, Hudson, and Connecticut (Gill 1980). The Blue-winged Warbler was once classified as rare in western Massachusetts in 1924, but now widely distributed throughout the state (Veit and Petersen 1993). Range expansion occurred earlier in central states, reaching northern Ohio (Peterjohn 1989b) and southern Michigan (Berger 1958) by early 1900s. Trends in Michigan have been historically well documented (Berger 1958, Will 1986, Payne 1991b) with this species well established in southern Michigan by early the 1920s. Now the Blue-winged Warbler is well established in central portions of the Lower Peninsula after expansion rate of about 3 km per year (Berger 1958, Will 1986, Payne 1991b). The first specimen collected in Ontario was in 1908 at Pt. Pelee along Lake Erie (Dunn and Garrett 1997). The first nests observed in 1956 in southern Ontario and northward expansion continues to the edge of the Canadian shield from Kingston to Muskoka (Mills 1987a). Overall, the range expansion of the Blue-winged Warbler continues in the north-central and eastern United States (Dunn and Garrett 1997).

Along the east coast, a range expansion of the Blue-winged Warbler in New York State has been documented great in detail. By 1914, this species was uncommon or local on southern and eastern Long Island and in the central Hudson Valley and valley of the Delaware, with a few records on Lake Ontario Plain (Eaton 1910). By 1971, this species was well-established in western New York State and through the Hudson River valley to the Albany region (Bull 1974). The Blue-winged Warbler arrived in Ithaca, in the Tompkins County area, by 1949 and increased to become as common as Golden-winged Warbler in 10 years (Short 1962). This species has expanded throughout the entire New York State portion of the Lake Ontario Plain by 1985, with rare reports throughout the St. Lawrence River valley by the 1990s (Confer 1998), but the Blue-winged Warbler is absent from higher elevations of the Adirondack Mountains (Dunn and Garrett 1997). 

The Blue-winged Warbler is a medium-distance Trans-Gulf Neotropical-Nearctic migrant where the breeding and wintering ranges do not overlap (Gill et al. 2020).

Birds start migration from wintering grounds in Central America, with wintering birds recorded through late March in Panama before heading north (Ridgely and Gwynne 1989) and mid-to late April in Costa Rica (Stiles and Skutch 1989), while migration occurs between March and April in northeast Mexico (Howell and Webb 2010). In the West Indies, wintering birds recorded through March, but occasionally May (Raffaele et al. 1998). Transients also recorded in Bermuda April 1-27 (Amos 1991). 

In the southern United States, spring migration in Texas begins in early April to early May, with extreme dates of March 10 and May 30 (Oberholser 1974), and in March into May in Florida (Robertson and Woolfenden 1992a), with earliest the date, based on specimens, March 23 (Stevenson and Anderson 1994). Farther north, spring migration occurs in the beginning of the second week of April, earliest record April 1, in Missouri, peaking in early May (Robbins and Easterla 1992), early through late May, earliest April 23, in Wisconsin (Robbins 1991), late April through early June, earliest records from April 27-30, in Minnesota (Janssen 1987), early April, earliest record March 27, through mid-May in Tennessee (Robinson 1990), April 22-May 20, earliest April 13, in Ohio (Peterjohn 1989), last few days of April through the second week of May in southeastern Pennsylvania (Gill et al. 2020), and the first week of May, earliest April 21, in Massachusetts (Veit and Petersen 1993). The spring migration period is usually short, lasting only about 2-3 weeks, at least in Ohio and southeastern Pennsylvania (Peterjohn 1989, Gill et al. 2020). In migration in south New Jersey, Blue-wing Warblers outnumbered Golden-winged Warblers by only 2:1 at Higbee Beach, Cape May County, in the 1920s, but now outnumber Golden-winged Warblers 30:1 (Sibley 1997).

Migrates commonly through eastern United States west to the eastern Great Plains and eastern and southern Texas (American Ornithologists' Union 1998).  The beginning of the fall migratory period is difficult to detect in many areas because of presence of breeding populations. However, available evidence suggests that migration may occasionally begin during late summer. Migrants recorded on Cape Island, Cape May, New Jersey, (where species does not breed but migrants often occur) as early as July 10; migration normally peaks there during second half of August, ending in late September, with stragglers recorded through October 27 (Sibley 1997). The earliest tower kill in Florida is from July 25 (Stevenson and Anderson 1994). In most portions of the United States, the exact beginning of the migration period is impossible to detect. In Wisconsin, birds observed occasionally in breeding areas through till August, while scattered migrating individuals occur through mid-September, with the latest records occurring October 31 and November 10 (Robbins 1991). The Blue-winged Warbler is rarely observed after the first week of September with late records not recorded after September 15 in Missouri (Robbins and Easterla 1992). Fall migration is under way by mid-August in Ohio, and most depart between September 10 and 20, occasionally lingering through mid-October, with an exceptionally late November 14 record (Peterjohn 1989b). The median banding date of August 17 on Appledore Island, in Maine (Morris et al. 1994). The highest daily fall counts have occurred between the dates of August 16 through to September 1 in Massachusetts, where latest date is October 29 (Veit and Petersen 1993). In Pennsylvania, migration under way by third week of August, but greatest numbers captured at banding stations during first 2 weeks of September, indicating a migration peak with the migration usually ending by late September, but stragglers have been observed through the first week of October (McWilliams and Brauning 2000). Fall migration occurs September in Tennessee, with the latest date recorded as October 31 (Robinson 1990). Peak dates of fall tower kill in Florida occurs from September 11-30 (Stevenson and Anderson 1994). Now regularly recorded northeast of breeding range during late fall in Newfoundland, the Maritime Provinces, and islands off Maine (Dunn and Garrett 1997). 

 

Classified as very rare in the central United States from North and South Dakota (e-bird database 2021). In Oklahoma the Blue-winged Warbler is considered a very rare migrant in northeast part of the state and it is even rarer in central Oklahoma where it is classified as a casual migrant (Baumgartner and Baumgartner 1992). This species is a very rare transient in eastern Kansas (Thompson and Ely 1992). 

In mid to western North America, the Blue-winged Warbler is a casual to accidental vagrant migrant species (Gill et al. 2020). This species is casual to very rare west from the Great Plains mainly in the spring and farther west mainly from May and September (e-bird database 2021). There are 2 records for Utah (Behle et al. 1985), 2 records Montana, 1 record for Idaho, at least 4 records for Wyoming, well over 40 records for Colorado, at least New Mexico, at least 10 records for Arizona, at least 7 records for Nevada (e-bird database 2021). In Canada, there are 2 records for Manitoba (May and November), a couple of records for Saskatchewan (May, June, November), with 2 records from Alberta (May and August) (e-bird database 2021). 

Outside of the United States, transient Blue-winged Warblers occur from early September through early October with an extremely early date of August 24 and late dates into mid-October in Bermuda (Amos 1991), with the bulk of birds recorded mainly by October but as early as August in the West Indies (Raffaele et al. 1998). Fall migration occurs from September and October in northeastern Mexico (Howell and Webb 2010). Birds arrive by early to mid-September in Costa Rica and recorded by mid-October in Panama (Ridgely and Gwynne 1989).

Blue-winged Warblers winter from southeastern San Luis Potosí, Mexico and less frequently from extreme southwestern Tamaulipas, Mexico, south along Atlantic slope of Mexico and Central America to central Panama. Within this area, this species winters south to northern Oaxaca and northern Chiapas, Mexico, and the northern halves of Guatemala, Honduras, and Nicaragua with scattered records along Pacific slope from Oaxaca, Mexico, south to El Salvador (Friedmann et al. 1950, Howell and Webb 2010). The Blue-winged Warbler is very uncommon to rare in Costa Rica, mainly in the Caribbean lowlands near the coast but occasionally up to 1,500 m (Stiles and Skutch 1989) and rare in the lowlands and foothills of western and central Panama (Wetmore et al. 1984, Ridgely and Gwynne 1989). The easternmost record from Chepo, in eastern Panama province (Ridgely and Gwynne 1989). One South American report in Sierra Nevada de Santa Marta, Colombia (Hilty and Brown 1986). Blue-winged Warblers are rare in the Greater Antilles, the Bahamas, and Cayman Island (Arendt 1992, Wunderle and Wade 1993, Raffaele et al. 1998); and is a casual to accidental vagrant in the Lesser Antilles (Raffaele 1989, Evans 1990). Uncommon, new winter resident in Bermuda, where not recorded in winter prior to 1974–1975 (Amos 1991). 

Reported infrequently in North America over the past couple of decades of National Audubon Society Christmas Bird Counts database with single records for California, Texas, Minnesota and 3 records from Kentucky (ACCBC 2020) There are over 20 sight reports during the winter months from Florida (Stevenson and Anderson 1994). There are also a few overwintering records from California (Small 1994, Hamilton et al. 2007, Tietz and McCaskie 2020).

Along the west Coast of North America, the Blue-winged Warbler is classified as a casual to accidental migrant vagrant species (Dunn and Alderfer 2011). In California, this is a casually occurring species that has increased in occurrence over the past 2 decades with 55 accepted records for the state by the California Bird Records Committee (Hamilton et al. 2007, Tietz and McCaskie 2020). Records have occurred throughout the year, including at least 3 winter records, but have a distinct peak in the latter half of May and September (Hamilton et al. 2007, Tietz and McCaskie 2020). In Oregon, the Blue-winged Warbler is an accidental migrant vagrant species with 4 records that are accepted by the Oregon Bird Records Committee (OFO 2020). These include: 1 breeding plumaged male from Page Springs CG, Harney County, on 20 May 1993; 1 adult male photographed at Indian Ford Creek, in Deschutes County July 24 -August 9, 2000; 1 bird at Riley Pond, in Harney County, on 9 September 2003; and 1 bird photographed at the Headquarters of the Malheur National Wildlife Refuge, in Harney County, on 20 September 2005 (OFO 2020). In Washington State, this species is an accidental migrant vagrant with 4 accepted records for the state by the Washington Bird Records Committee (Wahl et al. 2005, WBRC 2020). These records include: 1 bird at Ship Harbor Inn, Anacortes, Skagit County, on 17 September 17, 1990 (Wahl et al. 2005); 1 photographed and banded at ¾ of a mile Southwest of Camel Spring along McCarteney Creek, in Douglas County, on August 1, 2006 (Aanerud 2011) 1 male found at Forks, in Clallam County on June 23, 2011 (Mlodinow and Bartels 2010); and 1 found at College Place, in Walla Walla County, August 4-5, 2012 (Mlodinow and Bartels 2010). The Blue-winged Warbler is an accidental migrant vagrant in British Columbia with a single well documented sight record from Vancouver Island (Toochin et al. 2018).

The Blue-winged Warbler has occurred once in the Palearctic on the island of Corvo, in the Vila do Corvo, in the Azores from September 17-19, 2015 (e-bird database 2021).

The identification of the Blue-winged Warbler is covered in all standard North American field guides. This is a small wood-warbler species measuring 12 cm in length, with a wingspan of 20 cm, and weighing 8.5–9.0 grams (Dunn and Garrett 1997, Sibley 2000). The adult male has a bright-yellow crown and underparts, bold black eye-line, greenish-yellow back and nape, bluish-gray tail, and wings, and 2 distinct, white wing-bars often tinged with yellow (Dunn and Garrett 1997). The adult female is similar in appearance to the male, but slightly duller overall, with distinctly more olive crown and grayer eye-line; wing-bars often not as pronounced (Curson et al. 1994). Immature male like adult male, with the crown yellowish olive, contrasting less with nape and upperparts than in adult male (Dunn and Garrett 1997). The wing-bars likely tinged with yellow (Dunn and Garrett 1997). Some adult females may have brighter plumage than first-year males (Will 1986). The immature female is duller than the adult female; the crown is greenish and not contrasting with the nape and the upperparts, and dusky eye-stripe often indistinct (Curson et al. 1994, Sibley 2000). Plumages remain essentially unchanged throughout year, but the bill of the adult male is black in the spring and summer and dull pinkish brown with a dusky black culmen in fall and winter (Dunn and Garrett 1997); female bill similar but never as fully black as male bill (Dunn and Garrett 1997). 

The Blue-winged Warbler is slightly smaller than closely related Golden-winged Warbler (Vermivora chrysoptera) (Confer 1992). The combination of unmarked bright yellow underparts, white undertail-coverts, white tail-spots, white wing-bars, and dark eye-line make this species' plumage unique and unlikely to be confused with that of any other wood-warbler (Dunn and Garrett 1997). The Pine Warbler has a similar coloration and plumage pattern but is larger and less boldly marked, lacks the eye-line, and has duller wing-bars and much duller underparts that are usually much suffused with olive streaks (Curson et al. 1994). 

Hybrid phenotypes resulting from Blue-winged Warbler × Golden-winged Warbler pairings require scrutiny (Confer and Knapp 1977).

“Brewster's Warbler” hybrids (the most frequently occurring hybrid phenotype) look like Golden-winged Warblers without the bold, black facial pattern (Dunn and Garrett 1997). These hybrids feature the (dominant) black eye-line of the Blue-winged Warbler (Curson et al. 1994, Dunn and Garrett 1997). Underparts intermediate in color with white heavily washed with yellow (Sibley 2000). Wing-bars also intermediate but highly variable in amount of yellow color and separation (Dunn and Garrett 1997). The female Brewster's Warbler is paler, and the breast and belly may have more neutral gray than male Brewster's Warbler (Confer 1992).

“Lawrence's Warbler” hybrids combine the Golden-winged Warbler (homozygous recessive) face pattern with Blue-winged Warbler-like yellow plumage color (Dunn and Garrett 1997). The black throat and eye-patch inherited as a unit with rare exceptions (Curson et al. 1994, Dunn and Garrett 1997).

Backcrossing produces individuals that closely resemble either of the parental species, with some introgression (Curson et al. 1994, Dunn and Garrett 1997). Examples include Blue-winged Warblers with 2 yellowish, not white, wing-bars (Gill et al. 2020). Backcrossing of first-generation Brewster's Warbler with Golden-winged Warbler may produce Brewster's Warblers with pure-white underparts and broad, yellow wing-bars, like Golden-winged Warbler, but no black throat and eye-patch (Gill et al. 2020).

There have been 2 recent photo-documented examples of Blue-winged Warbler hybridizing with Prairie Warbler (Setophaga discolor) from the Great Lakes region of the United States (e-bird database 2021). There also a banded and photographed record of a female bird that involved a three-way hybrid involving a Brewster’s Warbler (Blue-winged Warbler X Golden-winged Warbler) that bred with and a male Chestnut-sided Warbler (Setophaga pensylvanica) and successfully reproduced further hybrid offspring (Toews et al. 2018). 

The Blue-winged Warbler has a distinctive sounding “beeeee bzzzz” which is a dry buzz followed by a longer, sizzling buzz on a slightly higher or sometimes lower pitch (Dunn and Garrett 1997, Sibley 2000). The only similar sounding warbler is the Golden-winged Warbler which contains 2 more short notes following the introductory buzz (Dunn and Garrett 1997). The call note of the Blue-winged Warbler is a sharp “tsik” or “swik” which is identical to that of the Golden-winged Warbler (Dunn and Garrett 1997). The flight note is a high somewhat buzzy “zwee” or “tzzii” that is often doubled (Dunn and Garrett 1997). 

The Blue-winged Warbler is an accidental migrant vagrant in British Columbia. The only record is of an immature bird found by Rick Toochin and Louis Haviland in a front yard along Sheringham Point Road, in Shirley, on September 20, 2008 (Toochin et al. 2018). This bird was well observed by both observers who had previous experience with this species in eastern North America where they are normally found (R. Toochin Pers. Comm.). Detailed field notes were taken at the time of the sighting (L. Haviland Pers Obs.). Though only a sight record, the timing of this observation fits perfectly into the overall pattern of vagrancy of the Blue-winged Warbler in western North America. This species is a generally found as either a late spring overshoot in late May into early June or in the month of September. As a vagrant, the Blue-winged Warbler should be watched for in known passerine vagrant traps and potentially at banding stations throughout the province. The number of west coast records has increased over the past 2 decades and it is highly likely this species will occur again in British Columbia. 

  

We would like to thank Don Cecile for editing the original manuscript.

 

ACCBC. 2020. Audubon Christmas Bird Count: Historical data. [Online Resource] Retrieved from https://netapp.audubon.org/cbcobservation/ [Accessed: December 1, 2021].

American Ornithologists' Union. 1998. Check-list of North American Birds. Seventh edition. American Ornithologists' Union, Washington, DC, USA.

Amos, E. J. R. 1991. A Guide to the Birds of Bermuda. Corncrake, Warwick, Bermuda.

Arendt, W. J. 1992. Status of North American migrant landbirds in the Caribbean region: A summary. In Ecology and Conservation of Neotropical Migrant Landbirds (J. M. Hagan III and D. W. Johnston, Editors), Smithsonian Institution Press, Washington, DC, USA. pp. 143–171.

Aanerud, K. 2011. Eighth Report of the Washington Bird Records Committee. Western Birds 11: 47.

Baumgartner, E. M., and A. M. Baumgartner. 1992. Oklahoma Bird Life. University of Oklahoma Press, Norman, OK, USA.

Behle, W. H., E. D. Sorenson, and C. M. White. 1985. Utah Birds: A Revised Checklist. Utah Museum of Natural History, Salt Lake City, UT, USA.

Berger, A. J. 1958. The Golden-winged-Blue-winged Warbler complex in Michigan and the Great Lakes area. Jack Pine Warbler 36: 37-72.

Buckelew, A. R., Jr., and G. A. Hall. 1994. The West Virginia Breeding Bird Atlas. University of Pittsburgh Press, Pittsburgh, PA, USA.

Bull, J. 1974. Birds of New York State. Doubleday Natural History Press, Garden City, NY, USA.

Confer, J. L. 1998. "Blue-winged Warbler." In Bull's birds of New York State., edited by E. Levine, 451-453. Ithaca, NY: Cornell Univ. Press.

Confer, J.L. and Knapp, K. 1977. Hybridisation and interactions between Blue-winged and Golden-winged Warblers. Kingbird 27: 181-190.

Confer, J.L. and Knapp, K. 1981. Golden-winged Warblers and Blue-winged Warblers: the relative success of a habitat specialist and a generalist. Auk 98: 108-114.

Confer, John L. 1992. Golden-winged Warbler. In The Birds of North America, No. 20 (A. Poole, P. Stettenheim, and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington D.C.: The American  Ornithologists' Union. 

Curson, J., D. Quinn, and D. Beadle. 1994. Warblers of the Americas: an Identification Guide. Houghton Mifflin Company, New York, NY, USA.

Dunn, J. L. and J. Alderfer. 2011. National Geographic Field Guide to the Birds of North America. National Geographic Society, Washington D.C. 574pp.

Dunn, J. L., and K. L. Garrett. 1997. A Field Guide to the Warblers of North America. Houghton Mifflin Company, Boston, MA, USA.

Eaton, E. H. 1910. Birds of New York. Introductory chapters; Waterbirds and gamebirds. New York State Museum, Memoir 12, Part 1. NY State Education Department, Albany University, Albany, NY, USA.

e-bird database. 2021. Explore species: Blue-winged Warbler. [Online Resource] Retrieved from https://ebird.org/canada/map/buwwar?neg=true&env.minX=&env.minY=&env.maxX=&env.maxY=&zh=false&gp=false&ev=Z&mr=1-12&bmo=1&emo=12&yr=all&byr=1900&eyr=2021 [Accessed: December 5, 2021].

Evans, P. G. H. 1990. Birds of the Eastern Caribbean. Macmillan Press, Ltd., London, United Kingdom.

Faxon, W. 1913. Brewster's Warbler (Helminthophaga leucobronchialis) a hybrid between the Golden-winged Warbler (Helminthophaga chrysoptera) and the Blue-winged Warbler (Helminthophaga pinus). Mem. Mus. Comp. Zool. 40:311-316.

Friedmann, H., L. Griscom, and R. Moore. 1950. Distributional checklist of the birds of Mexico, Part I. Pacific Coast Avifauna 29.

Gill, F. B. 1980. Historical aspects of hybridization between Blue-winged and Golden-winged warblers. Auk 97: 1-18.

Gill, F. B., R. A. Canterbury, and J. L. Confer. 2020. Blue-winged Warbler (Vermivora cyanoptera), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. [Online Resource] Retrieved from https://doi.org/10.2173/bow.buwwar.01 [Accessed: December 4, 2021].

Hamilton, R. A., M. A. Patten and R. A. Erickson. (editors). 2007. Rare Birds of California: A work of the California Bird Records Committee. Western Field Ornithologists, Camarillo, California. 

Hilty, S. L., and W. L. Brown. 1986. A Guide to the Birds of Colombia. Princeton University Press, Princeton, NJ, USA.

Howell, S. N. G., and S. Webb. 2010. A Guide to the Birds of Mexico and Northern Central America. Oxford University Press, New York, NY, USA.

Janssen, R. B. 1987. Birds in Minnesota. University of Minnesota Press, Minneapolis, MN, USA.

McWilliams, G. M., and D. W. Brauning. 2000. The Birds of Pennsylvania. Cornell University Press, Ithaca, NY, USA.

Mills, A. 1987a. "Blue-winged Warbler." In Atlas of the breeding birds of Ontario., edited by M. D. Cadman, P. F. J.   Eagles and F. M. Helleiner, 356-357. Waterloo, ON: Univ. of Waterloo Press.

Mlodinow, S. G. and M. Bartels. 2010. Tenth Report of the Washington Bird Records Committee (2010 – 2013). Western Birds 47: 106.

Morris, S. R., M. E. Richmond, and D. W. Holmes. 1994. Patterns of stopover by warblers during spring and fall migration on Appledore Island, Maine. Wilson Bulletin 106: 703–718.

Oberholser, H. C. 1974. The Bird Life of Texas. University of Texas Press, Austin, TX, USA.

OFO. 2020. Oregon Field Ornithologists – The Records of the Oregon Bird Records Committee July 2020. [Online resource] http://www. oregonbirds.org/index.html. [Accessed: December 27, 2020]

Payne, R. B. 1991b. "Blue-winged Warbler." In The atlas of breeding birds of Michigan., edited by R. Brewer, G. A. McPeak and Jr R. J. Adams, 384-385. East Lansing: Michigan State Univ. Press.

Peterjohn, B. G. 1989. The Birds of Ohio. Indiana University Press, Bloomington, IN, USA.

Raffaele, H. A. 1989. A Guide to the Birds of Puerto Rico and the Virgin Islands. Princeton University Press, Princeton, NJ, USA.

Raffaele, H., J. Wiley, O. Garrido, A. Keith, and J. Raffaele. 1998. A guide to the birds of the West Indies. Princeton University Press, Princeton, NJ, USA.

Ridgely, R. S., and J. Gwynne. 1989. A Guide to the Birds of Panama, with Costa Rica, Nicaragua, and Honduras. 2nd Edition. Princeton University Press, Princeton, NJ, USA.

Robbins, M. B., and D. A. Easterla. 1992. Birds of Missouri: Their Distribution and Abundance. University of Missouri Press, Columbia, MO, USA.

Robbins, S. D., Jr. 1991. Wisconsin Birdlife: Population and Distribution, Past and Present. University of Wisconsin Press, Madison, WI, USA.

Robertson, W. B., Jr., and G. E. Woolfenden. 1992. Florida Bird Species: An Annotated List. Florida Ornithological Society Special Publication 6.

Robinson, J. C. 1990. An Annotated Checklist of the Birds of Tennessee. University of Tennessee Press, Knoxville, TN, USA.

Shaffer, F. 1996. "Blue-winged Warbler." In The breeding birds of Quebec: atlas of the breeding birds of southern Quebec., edited by J. Gauthier and Y. Aubry, 1176-1177. Québec Region, Montréal: Assoc. québecoise des groupes d'ornithologues, Prov. of Quebec Soc. for the protection of birds, Can. Wildl. Serv., Environ. Canada.

Short, L. L. 1962. The Blue-winged Warbler and Golden-winged Warbler in central New York. Kingbird 12: 59-67.

Sibley, D. A. 1997. Birds of Cape May, second edition. Cape May Bird Observatory, New Jersey Audubon Society, Cape May, NJ, USA.

Sibley, D. A. 2000. The Sibley field guide to birds. Alfred A. Knopf, New York. 545pp.

Small, A. 1994. California Birds: Their Status and Distribution. Ibis Publishing Company, Vista, CA, USA.

Stevenson, H. M., and B. H. Anderson. 1994. The Birdlife of Florida. University Press of Florida, Gainesville, FL, USA.

Stiles, F. G., and A. F. Skutch. 1989. A Guide to the Birds of Costa Rica. Cornell University Press, Ithaca, NY, USA.

Thompson, M. C., and C. Ely. 1992. Birds in Kansas, Volume II. University of Kansas Museum of Natural History 12, Lawrence, KS, USA.

Tietz, J. and G. McCaskie. 2020. Update to Rare Birds of California: 1 January 2004 – 16 April 2020. [Online Resource] Retrieved from http://www.californiabirds.org/cbrc_book/update.pdf [Accessed: July 8, 2020].

Toochin, R., J. Fenneman, P. Levesque and D. Cecile. 2018. British Columbia Rare Bird List: Casual and Accidental Records: July 15, 2018: 5th Edition [Online Resource] Retrieved from http://ibis.geog.ubc.ca/biodiversity/efauna/documents/BC%20Rare%20Bird%20ListVersion-July-15-2018.pdf [Accessed: November 26, 2021].

Toews, D. P. L., H. M. Streby, L. Burket, and S. A. Taylor. 2018. A wood-warbler produced through both interspecific and intergeneric hybridization. Biol. Lett. 14: 20180557. [Online Resource] Retrieved from http://dx.doi.org/10.1098/rsbl.2018.0557 [Accessed: December 5, 2021].

Veit, R. R., and W. R. Petersen. 1993. The Birds of Massachusetts. Massachussetts Audubon Society, Lincoln, MA, USA.

Wahl, T. R, B. Tweit, and S. Mlodinow. 2005. Birds of Washington: Status and Distribution. Oregon State University Press, Corvallis, Oregon. 436pp.

WBRC. 2020. Washington Bird Records Committee – Summary of Decisions. Washington Ornithological Society, Seattle, WA. [Online resource] http://www.wos.org/wbrcsummaries.html. [Accessed: November 21, 2021].

Wetmore, A., R. F. Pasquier, and S. L. Olson. 1984. The Birds of the Republic of Panama, Part 4-Passeriformes: Hirundinidae (Swallows) to Fringillidae (Finches). Smithsonian Institution Press, Washington, DC, USA.

Will, T. C. 1986. The behavioral ecology of species replacement: Blue-winged and Golden-winged warblers in Michigan. Ph. D. diss., Univ. Michigan, Ann Arbor.

Wunderle, J. M., Jr., and R. B. Wade. 1993. Distribution of overwintering nearctic migrants in the Bahamas and Greater Antilles. Condor 95: 904–933.