Breeding range.—Townsend’s warbler breeds north to southern Alaska (Seldovia, Port Nell Juan, and Cordova); and southern Yukon (Lapie River and Sheldon Lake). East to eastern Yukon (Sheldon Lake and Lake Marsh); central to southeastern British Columbia (Atlin, Bear Lake, Tacla Lake, and Revelstoke); southwestern Alberta (Banff National Park); and western Montana (Fortine, Columbia Falls, Great Falls, and Red Lodge). South to central southern Montana (Red Lodge); northwestern Wyoming (Mammoth Hot Springs); northern Idaho (Falcon and Moscow); and southern Washington (Blue Mountains, Preston, and Mount Adams). West to western Washington (Mount Adams, Mount Rainier, Seattle, and Bellingham); western British Columbia (Comox, Vancouver Island, and the Queen Charlotte Islands); and southern Alaska (Craig, Baranof Island, Glacier, Cordova, and Seldovia).
Winter range.—The Townsend’s warbler is found in winter in two widely separated areas. It is found in varying numbers in the coastal region of California from Mount St. Helena, Sonoma County, south to San Diego, and on the Santa Barbara Islands. A specimen collected at Patagonia, southeastern Arizona on December 3, may have been wintering. It also winters in the mountains of western Mexico and Central America from Guerrero (Tlalixtaquilla); and the Federal District (Tlalpan); through Oaxaca (La Parada and Totontepec); Guatemala (Huehuetenango, Tecpán, Dueñas, and Guatemala); El Salvador (Los Esesmiles and Mount Cacaguatique); to central northern Nicaragua (Matagalpa).
Migration.—Late dates of spring departure are: El Salvador—San José del Sacore, March 16. Guatemala—Tecpán, May 2. Nayarit—Tres Marías Islands, May 11. Sonora—Oposura, May 31. Texas—Boot Spring, Chisos Mountains, May 16. New Mexico—Rinconada, May 6. Arizona—Rock Canyon, Santa Catalina Mountains, May 25. California—Buena Vista, May 10.
Early dates of spring arrival are: Hidalgo—Jacala, March 28. New Mexico—Apache, April 23. Arizona—Tombstone, April 3. Colorado—Loveland, May 11. Wyoming—Cheyenne, May 11. Montana—Columbia Falls, May 4. Idaho—Coeur d’Alene, April 29. Oregon—Sutherlin, April 21. Washington—Bellingham, April 25. British Columbia—Courtenay, March 28; Atlin, May 18. Alaska—Craig, April 27.
Late dates of fall departure are: Alaska—Ketchikan, September 5. British Columbia—Atlin, September 1; Okanagan Landing, September 15. Washington—Tacoma, October 3. Alberta—Jasper Park, September 8. Idaho—Priest River, September 10. Montana—Missoula, August 31. Wyoming—Laramie, October 18. Colorado—Fort Morgan, October 12. Utah—Bryce Canyon, October 7. Arizona—Mineral Creek, Pinal County, November 2. New Mexico—near Corona, October 18. Oklahoma—Kenton, September 27. Texas—Glenn Springs, Brewster County, October 19. Chihuahua—Durazno, November 7.
Early dates of fall arrival are: Oregon—Fremont National Forest, August 20. California—August 26. Utah—Beaver Creek Canyon, August 10. Arizona—San Francisco Mountain, August 21. Wyoming—Laramie, August 11. Colorado—Estes Park, August 14. New Mexico—Apache, August 2. Texas—Pulliam Canyon, Chisos Mountains, August 26. Chihuahua—Saltillo, August 28. Guatemala—Tecpán, September 2. El Salvador—Divisadero, September 27.
Casual records.—On May 12, 1868, a Townsend’s warbler was collected near Coatesville, Pa. A female specimen was collected September 17, 1939, at Gulfport, Miss. On August 18, 1934 one was reported seen at East Hampton, Long Island; another was closely observed by several competent observers in Prospect Park, Brooklyn, N. Y., May 8 to 10, 1947.
Egg dates.—British Columbia: 2 records, June 7 and 24.
Oregon: 3 records, June 7 to 21.
Washington: 18 records, May 24 to June 24; 9 records, June 8 to 19, indicating the height of the season (Harris).