the prothonotary warbler (protonotaria citrea) is a small songbird of the new world warbler family .
it is the only member of the genus protonotaria .
the prothonotary warbler is 13 cm long and weighs 12.5 g .
it has an olive back with blue-grey wings and tail , yellow underparts , a relatively long pointed bill and black legs .
the adult male has a bright orange-yellow head; females and immature birds are duller and have a yellow head .
in flight from below , the short , wide tail has a distinctive two-toned pattern that is white at the base and dark at the tip .
it breeds in hardwood swamps in extreme southeastern ontario and eastern united states .
it winters in the west indies , central america and northern south america .
it is a rare vagrant to western states , most notably california .
it is the only eastern warbler that nests in natural or artificial cavities , sometimes using old downy woodpecker holes .
the male often builds several incomplete , unused nests in his territory; the female builds the real nest .
it lays 37 eggs .
the preferred foraging habitat is dense , woody streams , where the prothonotary warbler forages actively in low foliage , mainly for insects and snails .
the song of this bird is a simple , loud , ringing sweet-sweet-sweet-sweet-sweet .
the call is a loud , dry chip , like that of a hooded warbler .
its flight call is a loud seeep .
these birds are declining in numbers due to loss of habitat .
they are also parasitized by the brown-headed cowbird (molothrus ater), or outcompeted for nest sites by the house wren (troglodytes aedon) .
it is listed as endangered in canada .
the species persists in protected environments such as south carolina's francis beidler forest currently home to more than 2,000 pairs , the densest known population .
this bird was named after prelates in the roman catholic church known as the protonotarii , who wore golden robes .
it was once known as the golden swamp warbler .
the prothonotary warbler became known in the 1940s as the bird that , in front of the house un-american activities committee , established a connection between whittaker chambers and alger hiss .
chambers had testified that hiss enjoyed bird-watching , and once bragged about seeing a prothonotary warbler .
hiss later testified to the same incident , causing many members to become convinced of the pair's acquaintance .
this bird is mentioned in a sand county almanac by aldo leopold as the " ewel of my disease-ridden woodlot", "as proof that dead trees are transmuted into living animals , and vice versa .
when you doubt the wisdom of this arrangement , take a look at the prothonotary .
" john james audubon's painting of a prothonotary warbler is the third plate in his birds of america .
