Blackburnian Warbler

The Blackburnian Warbler, a small New World warbler, is a creature of remarkable beauty. It is a diminutive passerine, measuring approximately 11 to 13 cm in length with a wingspan stretching from 20 to 22 cm. The average weight of an adult is a mere 9.7 grams, though this can increase slightly in the autumn months due to fat reserves. The male, in his summer plumage, is a spectacle of nature with a dark gray back, double white wing bars, and a yellowish rump. His crown is a rich dark brown, while his underparts are a pristine white, tinged with yellow and streaked with black. The head is a striking pattern of yellow and black, with a flaming-orange throat that sets him apart from all other North American warblers.

Identification Tips

The Blackburnian Warbler is almost unmistakable when seen well. The male's bright orange throat, yellow supercilium, and contrasting grey cheeks are distinctive. The female and fall male are less vibrant but still identifiable by their dull-yellow supercilium, yellow throat, and dark streaky sides and back. The Blackburnian Warbler's song is a series of high "swi" notes, often ascending in pitch, and their call is a high "sip."

Habitat

These warblers favor mature coniferous woodlands, particularly during the breeding season. They are found in the southeastern part of Canada's boreal forest and continue down through New England and the Appalachian Mountains in mixed woodlands rich with spruce and hemlocks.

Distribution

The Blackburnian Warbler breeds in eastern North America, from southern Canada to North Carolina, and winters in southern Central America and South America. They are rare vagrants to western Europe.

Behaviour

Blackburnian Warblers are solitary in winter and highly territorial during breeding. They do not typically mix with other passerine species outside of migration. However, during migration, they may join mixed foraging flocks with species like chickadees, kinglets, and nuthatches.

Song & Calls

Their songs are a simple series of high "swi" notes, which often ascend in pitch. Their call is a high "sip."

Breeding

The breeding season begins in mid-May to early June, with the nest being an open cup of twigs and bark, lined with lichens and moss. The female lays three to five whitish eggs, and the nest is usually placed on a horizontal branch, 2 to 38 meters above the ground.

Similar Species

The flame-throated warbler of Central America has an orange throat but lacks the contrasting blackish streaking and whitish underside of the male Blackburnian.

Diet and Feeding

Primarily insectivorous, the Blackburnian Warbler's diet is dominated by moth and butterfly larvae. They may also consume berries in winter and are known to forage in treetops, often helping to control populations of spruce budworm.

Conservation Status

The Blackburnian Warbler is currently listed as Least Concern by the IUCN. Despite the potential threat of habitat destruction, which could lead to significant habitat loss, the species continues to have a large range and stable numbers where habitat is appropriate.