is a rare but tolerably regular migrant through eastern North and South Dakota, suggesting that there is some as yet unknown breeding area. The species has been recorded in migration, more often in fall, in Wyoming, Colorado, Nebraska, Kansas, Oklahoma, and Texas. Observers at Aweme, Manitoba, in 38 years recorded it only twice. Another observer at Eastend, southwestern Saskatchewan, recorded it for the first time on September 21, 1937, after at least twenty years of continuous observation. On the basis of such information it seems probable that the species is slowly spreading its breeding range westward. _Winter range._--The principal winter home of the black-throated blue warbler is in the West Indies where it is found =north= to the Bahamas (Andros, Nassau, and Watling Islands). =East= to Puerto Rico (Río Piedras) and the Virgin Islands (St. Croix). =South= to Puerto Rico (Maricas); Hispaniola (Paraíso, Dominican Republic; and Jérémie, Haiti); Jamaica (Spanishtown); and the Swan Islands. =West= to the Swan Islands; Cozumel Island; Cuba (Habana); and the Bahamas (Andros). It is also casual north to southern Florida (Sanibel Island, Key West, and Sombrero Key); accidental in Guatemala (Cobán); and in northern South America; Venezuela (Ocumare and Rancho Grande); and Colombia (Las Nubes, Santa Marta region, and Pueblo Viejo). The species as outlined is divided into two subspecies or geographic races. The black-throated blue warbler (_D. c. caerulescens_) is found in Canada and in the United States south to Pennsylvania; Cairns' warbler (_D. c. cairnsi_) breeds in the Appalachian Mountains from southwestern Pennsylvania southward. _Migration._--Late dates of departure from the winter home are: Puerto Rico--Consumo, April 3. Haiti--Morne à Cabrits, May 6. Cuba--Habana, May 11. Bahamas--Cay Lobos, May 14. Early dates of spring arrival are: Florida--Fort Myers, March 4. Georgia--Fitzgerald, April 11. South Carolina--Spartanburg, April 5. North Carolina--Weaverville, April 19. Virginia--Lynchburg, April 21. District of Columbia--Washington, April 19. Pennsylvania--Swarthmore, April 25. New York--New York, April 28. Massachusetts--Amherst, May 2. New Hampshire--East Westmoreland, April 29. Maine--Auburn, May 3. Nova Scotia--Scotch Lake, May 7. Quebec--Quebec, May 7. Louisiana--New Orleans, March 22. Tennessee--Chattanooga, April 14. Kentucky--Lexington, April 24. Illinois--Urbana, April 26. Ohio--Canton, April 22. Michigan--Battle Creek, April 28. Ontario--Reaboro, May 3. Missouri--St. Louis, April 18. Iowa--Sigourney, April 21. Wisconsin--Ripon, April 28. Minnesota--Hibbing, May 8.