Black-throated Blue Warbler

Black-throated Blue Warbler is a rarity in Sonoma County. Its presence has been confirmed here on only a dozen or so occasions in the past 20 years (writing in 2013)--most recently (and most often) at Owl Canyon, Bodega Bay. A lone adult male showed up there on October 11, 2013, staying for nearly two weeks, affording many local birders a first look at this beautiful Eastern warbler. Normally Black-throated Blue Warbler lives in extreme Southeastern Canada, New England, and into central Pennsylvania, with a more darkly colored subspecies (known locally as Cairns’ Warbler) in the southern Appalachian Mountains as far south as northeastern Georgia. Black-throated Blue Warbler winters mainly in the West Indies and northern South America. In other words, there’s no reason for this bird to be in Sonoma County at all, but strays find their way here from time to time.

Adult males, as in the photo above, are unmistakable: Blue and black above, snow white below, with a white patch at the base of the primaries that stands out. Females are very different, however, being mostly a drab, brownish olive above and buff below, paler at the throat and vent. A pale eyebrow, pale arc under the eye, and a pale malar stripe contrast with a dusky cap and cheek. Adult females have a pale patch at the base of the primaries, like males, but it’s less contrasty in the female and absent in young females. Black-throated Blue Warbler shows greater sexual dichromatism than any other North American wood warbler.

Black-throated Blue Warbler is among the many warblers formerly placed in the genus Dendroica but now in the genus Setophaga. Older sources will call this bird Dendroica caerulescens.

English synonyms: Cairns' Warbler

Black-throated Blue Warbler in other languages--German: Blauer Waldsänger, Blaurücken-Waldsänger; Spanish: Bijirita Azul de Garganta Negra, Chipe Azul y Negro, Chipe Azulnegro, chipe azul-negro, Chipe azuloso, Cigüita Azul Garganta Negra, Ciguíta Azul, Garganta Negra, Reinita Azul, Reinita azul y negro, Reinita Azulada, Reinita Azulinegra, Reinita Dorsiazul, Reinita Negriazul; French: Fauvette bleue à gorge noire, Paruline à épaules bleues, Paruline bleue, Paruline bleue à gorge noire; Russian: Синеспинный лесной певун; Chinese: 黑喉蓝林莺; Japanese: ノドグロルリアメリカムシクイ(nodoguroruriamerikamushikui);

(Language information from Avibase, Birds of Europe (Mullarney et al, Princeton Field Guide Series), and Birds of Asia (Mark Brazil, Princeton Field Guide Series).

Selected county sightings: Owl Canyon, Bodega Bay (10/11/13 to 10/24/13, Mike Parmeter)--the bird photographed above. Earlier sightings to 2001 from Parmeter and Wight: Bodega Marine Lab Entrance (10/3/04); Owl Canyon (9/20/03-9/21/03); Campbell Cove (9/21/01-9/24/01). Selected older sightings from Bolander and Parmeter: Owl Canyon (11/2/99); Owl Canyon (11/4/98); Owl Canyon (9/30/98-10/3/98); Owl Canyon (11/6/95-11/7/95); Owl Canyon (11/1/95); Campbell Cove (10/9/94).