the golden-winged warbler , vermivora chrysoptera , is a new world warbler , 11.6 cm long and weighing 8-10 g .
it breeds in southeastern and south-central canada and the appalachian mountains northeastern to north-central usa .
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 .
this is a small warbler , measuring 11.6 cm (4.6 in) long and weighing 810 g (0.280.35 oz) .
the male has black throat (suggestive of the throat patch of a chickadee), black ear patch bordered in white , yellow crown and wing patch .
females feature a similar coloration pattern , but the black is replaced with light grey .
in both sexes , extensive white on the tail is conspicuous from below .
underparts are grayish white and the bill is long and slender .
unlike most warblers , juveniles can be reliably sexed (using throat patch color) approximately 15 days after fledging .
pure breed golden-winged warblers are almost unmistakable if seen well .
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 .
this is a very rare vagrant to western europe , with a single record of a bird wintering in a supermarket car park in maidstone , kent in 1989.golden-winged warblers breed in open scrubby areas , wetlands , and occasionally mature forest adjacent to those habitats .
they lay 3-6 eggs (often 5) in a highly concealed cup nest on the ground or low in a bush .
these birds feed on insects , and spiders , most often leaf-roller caterpillars .
golden-winged warblers have strong gaping (opening) musculature for their bill , allowing them to uncover hidden caterpillars .
the song is highly variable , but is most often heard as a trilled bzzzzzzz buzz buzz buzz .
the call is a buzzy chip or zip .
this species forms two distinctive hybrids with blue-winged warbler where their ranges overlap in the great lakes and new england area .
the commoner , 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 which is 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 .
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 .
