Bay-breasted Warbler

The Bay-breasted Warbler, Dendroica castanea , is a New World warbler. It breeds in northern North America in Canada, and into the Great Lakes region and northern New England.

It is migratory, wintering in northern South America. This is a very rare vagrant to western Europe.

This species is closely related to Blackpoll Warbler, but has a more southerly breeding range and more northerly wintering area.

The summer male Bay-breasted Warbler is unmistakable. It has a grey back, black face, and chestnut crown, flanks and breast. There are yellow neck patches, and the underparts are white. There are two white wing bars.

Breeding females are a washed out version of the male, greyish above and white below, with a much weaker head pattern and chestnut reduced to small flank patches and tints in the grey crown.

Non-breeding birds have a greenish head, greenish upperparts and a yellowish breast, with the colour extending to the belly in young birds. The two white wing bars are always present. They differ from non-breedering Blackpoll Warblers in the absence of breast streaks.

The breeding habitat is coniferous woodland. Bay-breasted Warblers nest in a conifer, laying 3-5 eggs in a cup nest, more in Spruce Budworm years.

These birds feed on insects, and numbers vary with the abundance of the Spruce Budworm. They will also take berries and nectar in winter.

The song is a repetitive high-pitched si si si.

Reference

New World Warblers by Curson, Quinn and Beadle, ISBN 0-7136-3932-6