Golden-winged warbler

The golden-winged warbler (Vermivora chrysoptera) is a New World warbler. It breeds in southeastern and south-central Canada and in the Appalachian Mountains in northeastern to north-central United States. The majority (~70%) of the global population breeds in Wisconsin, Minnesota, and Manitoba. Golden-winged warbler populations are slowly expanding northwards, but are generally declining across its range, most likely as a result of habitat loss and competition/interbreeding with the very closely related blue-winged warbler, Vermivora cyanoptera. Populations are now restricted to two regions: the Great Lakes and the Appalachian Mountains. The Appalachian population has declined 98% since the 1960s and is significantly imperiled. The U.S. Fish and Wildlife Service has been petitioned to list the species under the Endangered Species Act of 1973 and is currently reviewing all information after issuing a positive finding. Upon review, the U.S. Fish and Wildlife Service found that the petition to list the species as endangered or threatened presents "substantial scientific or commercial information indicating that listing the golden-winged warbler may be warranted."

Etymology
The genus name Vermivora is from Latin vermis "worm", and vorare, "to devour", and the specific chrysoptera is from Ancient Greek khrusos, "gold", and pteron, "wing".

Description
This is a small warbler, measuring 11.6 cm long, weighing 8 - 10 g, and having a wingspan range 20 cm. The male has black throat, black ear patch bordered in white, and a yellow crown and wing patch. Females appear similar to males, with a light gray throat and light gray ear patches. In both sexes, extensive white on the tail is conspicuous from below. Underparts are grayish white and the bill is long and slender. Juvenile individuals appear similar to females, regardless of sex.

Life history
Golden-winged warblers are migratory, breeding in eastern North America and wintering in southern Central America and the neighboring regions in Colombia, Venezuela, and Ecuador. They are very rare vagrants elsewhere.

Golden-winged warblers breed in open scrubby areas, wetlands, and mature forest adjacent to those habitats. They lay 3–6 eggs (often 5) in a concealed cup nest on the ground or low in a bush.

Golden-winged warblers feed on insects, spiders, and caterpillars. They have strong gaping (opening) musculature around their bill, allowing them to uncover hidden caterpillars.

Their song is variable, but is most often perceived as a trilled bzzzzzzz buzz buzz buzz. The call is a buzzy chip or zip.

Male Golden-winged warblers use their brilliant yellow crowns, black throats, and white tail feather patches to signal habitat quality. Birds with more ornate ornaments protect higher quality territories and are typically less aggressive than their less brilliantly-colored conspecifics. However, ornamentation has not been shown to be linked with overall reproductive success. This is likely because golden-winged warblers with less ornamentation likely compensate for this with increased aggression.

Five geotracked golden-winged warblers in Tennessee were observed migrating hundreds of miles south, presumably avoiding tornadic storms, in April 2014. Individuals left prior to the arrival of the storm, perhaps after detecting it due to infrasound.

Habitat Selection
Golden-winged warblers are neotropical-nearctic migrants, and their habitat selectivity varies seasonally. Golden-winged warblers wintering in Costa Rica select premontane evergreen forest rather than tropical dry forest plant communities. Golden-winged warblers forage in hanging dead leaves, which are often a result of intermediate disturbances to the forest plant community.

During the breeding season, golden-winged warblers nest in shrubland and regenerating forest communities created and maintained by disturbance. This dependency on early-successional plant communities is part of the reason golden-winged warbler populations are declining.

Hybridization
This species forms two distinctive hybrids with blue-winged warblers where their ranges overlap in the Great Lakes and New England area. The more common, genetically dominant Brewster's warbler is gray above and whitish (male) or yellow (female) below. It has a black eyestripe and two white wingbars.

The rarer recessive Lawrence's warbler has a male plumage with green and yellow above and yellow below, with white wing bars and the same face pattern as male golden-winged. The female is gray above and whitish below with two yellow wing bars and the same face pattern as female golden-winged. Another rare recessive hybrid form is Burket's warbler, which has been noted in the same geographic area as Brewster's and Lawrence's. Burket's warbler was first documented by researchers at Cornell University's Lab of Ornithology. Brewster's, Lawrence's, and Burket's warblers can vary considerably in their physical features and sing songs of either blue-winged or golden-winged warblers. The colour of the throat patch reliably correlates with hybrid type, but colour of the underparts is highly variable between different hybrids.

Genetic introgression occurs across their range, producing cryptic hybrids (morphologically pure individuals with small amounts of blue-winged warbler DNA). These hybrids may be present in low numbers even on the edges of golden-winged warbler range, far from any populations of blue-winged warblers.

Hybridization between golden-winged warblers and blue-winged warblers is likely occurring at a much higher rate than initially thought. Genetic analysis has allowed scientists to more accurately quantify extra-pair copulation, and one study showed EPC was occurring in 55% of golden-winged warbler nests, resulting in phenotypic golden-winged warblers that were actually hybrids. Traditional indicators of the hybrid status of an individual, such as colouration of the underparts, are also

Interspecific interactions
In 2015, scientists observed a strange event. A female golden-winged warbler abandoned her two fledgling chicks 5 and 9 days after fledging. The two chicks were subsequently "adopted" by a male black-and-white warbler, which fed the fledglings for 23 days until they reached independence.

Books

 * 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, DC: The American Ornithologists’ Union.

Thesis

 * Demmons TD. M.Sc. (2000). Nest site selection and nest predation patterns at forest-field edges. Queen's University at Kingston (Canada), Canada.
 * Hamel PB. Ph.D. (1981). A HIERARCHICAL APPROACH TO AVIAN COMMUNITY STRUCTURE. Clemson University, United States, South Carolina.
 * Highsmith RT. Ph.D. (1989). Function, form, and recognition of the songs of golden-winged warblers (Vermivora chrysoptera) and blue-winged (V. pinus) warblers. University of Massachusetts Amherst, United States, Massachusetts.
 * Will TC. Ph.D. (1986). THE BEHAVIORAL ECOLOGY OF SPECIES REPLACEMENT: BLUE-WINGED AND GOLDEN-WINGED WARBLERS IN MICHIGAN. University of Michigan, United States, Michigan.

Articles
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 * Andre JB. (1979). The Golden-Winged Warbler Vermivora-Chrysoptera In Coastal Carolina USA A Recent Record And Comments On Its Fall Migration. Chat. vol 43, no 3.
 * Bannon P. (1986). Brewster's Warbler Vermivora-Chrysoptera X Vermivora-Pinus Backcross Breeding In Huntingdon County Quebec Canada. Canadian Field Naturalist. vol 100, no 1. pp. 118–119.
 * Boal CW, Sibley FC, Estabrook TS & Lazell J. (2006). Insular and migrant species, longevity records, and new species records on Guana Island, British Virgin Islands. Wilson Journal of Ornithology. vol 118, no 2. pp. 218–224.
 * Carpentier AG. (1983). Presumed Breeding Record Of Brewsters X Brewsters Warbler Vermivora-Chrysoptera-X-Vermivora-Pinus In Ontario Canada. Canadian Field Naturalist. vol 97, no 4. pp. 458–459.
 * Confer JL. (1992). Vermivora chrysoptera: Golden-winged warbler. Birds of North America. vol 0, no 20. pp. 1–15.
 * Confer JL. (2006). Secondary contact and introgression of golden-winged warblers (Vermivora chrysoptera): Documenting the mechanism. Auk. vol 123, no 4. pp. 958–961.
 * Confer JL & Knapp K. (1981). Golden-Winged Warblers Vermivora-Chrysoptera And Blue-Winged Warblers Vermivora-Pinus The Relative Success Of A Habitat Specialist And A Generalist. Auk. vol 98, no 1. pp. 108–114.
 * Confer JL, Larkin JL & Allen PE. (2003). Effects of vegetation, interspecific competition, and brood parasitism on Golden-winged Warbler (Vermivora chrysoptera) nesting success. Auk. vol 120, no 1. pp. 138–144.
 * Confer JL & Tupper SK. (2000). A reassessment of the status of Golden-winged and Blue-winged Warblers in the Hudson Highlands of southern New York. Wilson Bulletin. vol 112, no 4. pp. 544–546.
 * Dabrowski A, Fraser R, Confer JL & Lovette IJ. (2005). Geographic variability in mitochondrial introgression among hybridizing populations of Golden-winged (Vermivora chrysoptera) and Blue-winged (V-pinus) Warblers. Conservation Genetics. vol 6, no 5. pp. 843–853.
 * Doherty P. (1992). Golden-winged warbler: New to the western Palearctic. British Birds. vol 85, no 11. pp. 595–599.
 * Ewert DN. (1981). The Occurrence Of Closely Related Species Pairs In Central Michigan USA Willow Flycatchers Empidonax-Traillii And Alder Flycatchers Empidonax-Alnorum And Golden-Winged Warblers Vermivora-Chrysoptera And Blue-Winged Warblers Vermivora-Pinus. Jack Pine Warbler. vol 59, no 3. pp. 95–98.
 * Ferguson RS. (1981). Summer Birds Of The Northwest Angle Provincial Forest And Adjacent Southeastern Manitoba Canada. Syllogeus. vol 31, pp. 1–23.
 * Gill FB. (1980). Historical Aspects Of Hybridization Between Blue-Winged Warblers Vermivora-Pinus And Golden-Winged Warblers Vermivora-Chrysoptera. Auk. vol 97, no 1. pp. 1–18.
 * Gill FB. (1987). Allozymes And Genetic Similarity Of Blue-Winged And Golden-Winged Warblers. Auk. vol 104, no 3. pp. 444–449.
 * Gill FB. (1992). Golden-winged warbler Vermivora chrysoptera. Brauning, D. vol W, p. Atlas of breeding birds in Pennsylvania.
 * Gill FB. (1997). Local cytonuclear extinction of the golden-winged warbler. Evolution. vol 51, no 2. pp. 519–525.
 * Gill FB. (2004) BLUE-WINGED WARBLERS (VERMIVORA PINUS) VERSUS GOLDEN-WINGED WARBLERS (V. CHRYSOPTERA). The Auk. Vol 121, no 4. p. 1014 (5 pages)
 * Hamel P & Wright LM. (1979). Lawrences Warbler Vermivora-Chrysoptera-X-Vermivora-Pinus At Francis-Beidler Forest 1st Sight Record For South-Carolina USA. Chat. vol 43, no 3. pp. 66–67.
 * Hanowski JM, Christian DP & Nelson MC. (1999). Response of breeding birds to shearing and burning in wetland brush ecosystems. Wetlands. vol 19, no 3. pp. 584–593.
 * Highsmith RT. (1989). The Singing Behavior Of Golden-Winged Warblers. Wilson Bulletin. vol 101, no 1. pp. 36–50.
 * Klaus NA. (2004). Status of the golden-winged warbler in North Georgia, and a nesting record of the Lawrence's Warbler. Oriole. vol 69, no 1-2. pp. 1–7.
 * Klaus NA & Buehler DA. (2001). Golden-winged Warbler breeding habitat characteristics and nest success in clearcuts in the southern appalachian mountains. Wilson Bulletin. vol 113, no 3. pp. 297–301.
 * Koonce AE. (2005). The role of juvenile dispersal in the replacement of golden-winged warblers by blue-winged warblers. Natural Resource Modeling. vol 18, no 4. pp. 537–547.
 * Lacki MJ. (2000). Surveys of bird communities on Little Black and Black mountains: Implications for long-term conservation of Montane birds in Kentucky. Journal of the Kentucky Academy of Sciences. vol 61, no 1. pp. 50–59.
 * Leichty ER & Grier JW. (2006). Importance of facial pattern to sexual selection in golden-winged Warbler (Vermivora chrysoptera). Auk. vol 123, no 4. pp. 962–966.
 * Rayner WJ. (1988). Male Golden-Winged Warbler Attends Blue-Winged Warbler Nest. Ontario Birds. vol 6, no 3. pp. 106–107.
 * Rich T. (1981). The Golden-Winged Warbler Vermivora-Chrysoptera New-Record In Idaho USA. Western Birds. vol 12, no 1.
 * Rossell CR Jr. (2001). Song perch characteristics of Golden-winged Warblers in a mountain wetland. Wilson Bulletin. vol 113, no 2. pp. 246–248.
 * Rossell CR Jr., Patch SC & Wilds SP. (2003). Attributes of golden-winged warbler territories in a mountain wetland. Wildlife Society Bulletin. vol 31, no 4. pp. 1099–1104.
 * Roth AM & Lutz S. (2004). Relationship between territorial male Golden-winged Warblers in managed aspen stands in northern Wisconsin, USA. Forest Science. vol 50, no 2. pp. 153–161.
 * Shadick S. (1986). Golden-Winged Warbler At Duck Mountain Saskatchewan Canada. Blue Jay. vol 44, no 4. pp. 245–246.
 * Shapiro LH, Canterbury RA, Stover DM & Fleischer RC. (2004). Reciprocal introgression between Golden-Winged Warblers (Vermivora chrysoptera) and Blue-Winged Warblers (V. pinus) in eastern North America. Auk. vol 121, no 4. pp. 1019–1030.
 * Stenzler LM, Fraser R & Lovette IJ. (2004). Isolation and characterization of 12 microsatellite loci from Golden-winged Warblers (Vermivora chrysoptera) with broad cross-taxon utility in emberizine songbirds. Molecular Ecology Notes. vol 4, no 4. pp. 602–604.