Spring migratory birds: Black-throated Blue Warbler

Female Black-throated Blue Warbler. “Yhey usually show a single mark that confirms their identity – a small white patch in the bend of the wing.”

Black-throated Blue Warbler
Setophaga caerulescens

by Greg Hanisek. Photos and videos by Gilles Carter
May 9, 2022 — The Black-throated Blue Warbler, stunningly unique in its adult male garb, is quite average in other ways.

It’s never as rare or hard to find as a Mourning Warbler, and never as abundant at the height of migration as a Yellow-rumped (Myrtle) Warbler, or a Palm Warbler.

It doesn’t fit the mold of confusing fall warblers either. Once the adult males attain their alternate (breeding) plumage, they maintain that appearance year-round.

Their sexual dimorphism is extreme, however. The females bear virtually no resemblance to the males. They’re almost uniquely nondescript, to the point that no other warbler looks like them.

Fortunately for the puzzled observer, they usually show a single mark that confirms their identity – a small white patch in the bend of the wing, like an old-fashioned pocket square.

Actually, the adult male has one too, but the male is so immediately recognizable that you don’t notice what’s a standout field mark on its mate.

The species typically arrives from its Caribbean wintering grounds in late April and peaks during the warbler high point in May.

In fall they pass through from late August to mid-October, with a few lingering longer. As with a number of warbler species, the final appearances have been getting later.

Black-throated Blues nest in our state and can be rather easy to find in their preferred habitat in the Northwest Corner.

They prefer shady woodland understory, and our birds are especially attracted to Mountain Laurel thickets. Their wheezy songs announce their presence.

Female Black-throated Blue Warbler.