Geography/Habitat:

The Black-throated Blue Warbler, (Setophaga caerulescens), was first described by German naturalist Joseph Frederick Gmelin in 1789. Formerly part of the Motocilla and then Dendroica genus, its taxonomy is still poorly defined. Two subspecies are recognized but this is still disputed.

Black-throated Blues breed in the Northeast US and Eastern Canada as far South as the Carolinas. They Winter in the West Indies, Eastern Mexico and Belize. Preferred habitats are both deciduous and coniferous woodlands especially those with dense undergrowth in the Summer. In Winter woodland is still preferred but often found in parks and gardens. Note they are an understory bird and are typically found a few feet from the ground.

Breeding season is May through August and often two clutches are incubated. Note that polygamy is common in this species and roughly 50% of males have different mates in any given year. The nest is a simple cup made of bark, grass, twigs, hair, etc. Three to five brown speckled eggs are laid and are incubated for 12-13 days by the female. The young fledge after a further ten days. Note Black-throated Blues are a common target for cowbirds and become adoptive parents for cowbird young.

Black-throated Blue Warblers are insectivores and typically forge low to the ground but will go higher when food supply is short with males typically feeding higher than females. In Winter they will supplement their diet with some berries and fruit.

Identification

Black-throated Blue Warbler males are unmistakable. They are small with dark blue up-perparts, a black face and throat, white underparts and a diagnostic white wing patch. The female has olive green/blue upperparts, yellowish underparts, a white eyebrow and again a white wing patch.

The song is a buzzy “ zee-zeeee-zeeee-zee” and the call is a harsh “tuk”.

Interesting Facts

• Black-throated Blues are originally described as 2 different species due to their strong sexual dimorphism
• They are typically very tame and can often be approached quite closely
• A group of warblers is known as a bouquet, a confusion, a fall or a wrench.