Anguilla, Antigua and Barbuda, Aruba, Bahamas, Barbados, Belize, Canada (P), Cayman Islands, Colombia, Costa Rica, Cuba, Dominica, Dominican Republic, Guadeloupe, Guatemala, Haiti, Honduras, Jamaica (NB), Martinique, Mexico, Montserrat, Netherlands Antilles, Panama, Puerto Rico, St Kitts and Nevis, St Lucia, St Vincent and The Grenadines, Trinidad and Tobago, Turks and Caicos Islands, USA (B), Venezuela, Virgin Islands (British) (NB), Virgin Islands (U.S.) (NB).
Vagrant to Greenland, St Pierre and Miquelon (P).
Population
Estimated population is 2,000,000 (2010).
Black-throated Blue Warbler (Setophaga caerulescens) [XC260204]
by Denis Provencher from Algonquin Highlands, Haliburton County, Ontario, Canada (call)
Black-throated Blue Warbler (Setophaga caerulescens) [XC178552]
by Paul Marvin from Sudbury, Middlesex, Massachusetts, United States (song)
Subspecies
One record of hybridization, probably with Yellow Warbler (Setophaga petechia). Validity of subspecies cairnsi has been questioned, on the basis that, in males at least, differences from nominate are not constant (cairnsi-type males occur in nominate population, and vice versa).
The following 2 subspecies are recognised:
caerulescens (Gmelin, 1789) - Breeds in southern Canada from Saskatchewan (irregular) and southern Ontario east to Nova Scotia and in north-eastern USA from Minnesota east to New England; migrates to Caribbean (mainly Bahamas and Greater Antilles), small numbers to eastern Middle America.
cairnsi (Coues, 1897) - Breeds eastern USA in Appalachians from south-western Pennsylvania south to northern Georgia; migrates to Caribbean, some to eastern Middle America.