Figure 278. Unlike most vagrant Dendroica warblers, Black-throated Blues are found in California’s southeastern deserts nearly as often as they are encountered along the coast. The CBRC reviewed records of this species from 1972 and 1973 only. This brilliant first-fall male was photographed in October 1993 at Corn Spring in Riverside County (Herbert Clarke).

 

Figure 400. The Black-throated Blue Warbler is a regular fall vagrant to California, occurring in nearly equal numbers on the coast and in the desert. This female was photographed on 11 October 1998 at Galileo Hill in Kern County (Larry Sansone).

 

 

 

 

 

BLACK-THROATED BLUE WARBLER Dendroica caerulescens (Gmelin, 1789)

Accepted: 5 (71%)	Treated in Appendix H: no
Not accepted: 2	CBRC review: 1972 and 1973 records
Not submitted/reviewed: NA	Large color image: see Figures

This warbler breeds from southeastern Manitoba across southeastern Canada to the Maritime Provinces. The southern breeding limit extends from northeastern Minnesota east to New England, and south through the Appalachian Mts. to northern Georgia. As with the Cape May Warbler, migration takes most birds through Florida to wintering grounds in the northern West Indies. Migrants are very rarely encountered along the coast of the western Gulf of Mexico or on the Great Plains. Wintering birds are found rarely to uncommonly elsewhere in and adjacent to the Caribbean Sea and in northern South America, casually in the United States (exceptionally north to southern Canada) and in Bermuda. Migrants and wintering birds are casual to rare in the West—from southeastern Alaska (NAB 56:91–92, 211) and southern British Columbia south to Baja California Sur—and in northern mainland Mexico. The species is an accidental vagrant to Greenland, Iceland, and the Azores (Alfrey 2006).

California’s first Black-throated Blue Warbler was a first-fall female that spent three weeks on Southeast Farallon Island before being found dead on 17 November 1886 (Bryant 1888, CAS 54107). The state has since accumulated nearly 700 records, greater than 95% of them in fall (4 September–20 December, peaking in October and early November). Records from spring (chiefly 26 May–17 June) and winter are few. This species and the Magnolia Warbler are more frequently encountered in California’s deserts than are other eastern Dendroica warblers, although both are decidedly scarce in the Salton Sink (Patten et al. 2003).

Within the family Parulidae, the first known bilateral gynandromorph (an aberration during somatic development in which an individual forms a “male” side mirrored by a “female” side) was a vagrant Black-throated Blue Warbler photographed on 24 October 1987 at Stovepipe Wells in Inyo County (Patten 1993c, Graves et al. 1996). Since then, two more “undecided” Black-throated Blues have been recorded in the East (Guthrie and Cook 2000; NAB 60:173). The only other warbler reported as exhibiting this phenomenon is the Common Yellowthroat (Peterson and Howard 1999).