Winter range.—The Pacific, Gulf, and South Atlantic coasts of the United States, the West Indies, Central America, and northern South America. North to Washington (Dungeness Spit, and Smith Island); Texas (Brownsville and Corpus Christi); Louisiana (Cameron and Vermilion Parishes); Alabama (Dauphin Island); and rarely, North Carolina (Pea Island). East to rarely, North Carolina (Pea Island and Fort Macon); South Carolina (Charleston); Georgia (Blackbeard Island); Florida (Amelia Island, and Fort Myers); Cuba (Guantanamo); and Trinidad. South to Trinidad; Venezuela (Margarita Island); probably northern Colombia (Sabanilla); probably Costa Rica (Barranca Puntarenas); Tehuantepec (Tehuantepec City); and Lower California (La Paz). West to Lower California (La Paz); California (San Diego County, Alameda, Oakland, and Berkeley); and Washington (Point Chehalis; Seattle, and Dungeness Spit). It also has been detected in winter on San Clemente Island, off the coast of southern California.
Spring migration.—The spring movement of birds that have wintered on the South Atlantic coast is imperfectly known, there being available no interior records that indicate the route by which they reach the breeding grounds. The species has been detected at Long Beach, New York, as early as April 25, and at Mastic, New York, on May 12, while late spring departures from South Carolina have been noted at Charleston on May 8, and from Mastic, New York, on June 2.
Early dates of arrival in the West are: Arizona, Fort Verde, April 11, and San Pedro River, April 17; Colorado, Denver, May 2, and Loveland, May 9; Nevada, Smoky Creek, May 6; Idaho, Meridian, May 6; British Columbia, Sumas, April 20, and Chilliwack, April 26; and Alaska, Kuiu Island, April 28, Craig, May 2, Patterson's Bay, May 7, Admiralty Island, May 8, Fort Kenai, May 12, Hooper Bay, May 14, and Prince of Wales Island, May 15.
Late dates of spring departure at western points are: Texas, Somerest, May 5, San Angelo, May 6, Seadrift, May 8, and Tom Green and Concho Counties, May 12; Kansas, Lawrence, May 26; South Dakota, Vermilion, May 24, and Forestburg, May 26; lower California, San Quentin Bay, May 10; California, Fresno, May 12, Santa Barbara, May 16, Los Angeles, May 19, Alameda, May 21, and Owens Lake, June 1; Oregon, Mercer, May 14; Washington, Ilwaco, May 18, Neah Bay, May 24, Clallam Bay, May 25, and Quillayute Needles, May 30.
Fall migration.—Early dates of arrival in the fall are: British Columbia, Courtenay, July 7, Nootka Sound, July 23, and Okanagan Landing, July 28; Washington, Cape Flattery, July 2, Destruction Island, July 3, and Granville, July 4; Oregon, Cow Creek Lake, July 4; California, Santa Barbara, July 3, Fresno, July 5, and Tulare Lake, July 7; Lower California, San Quentin, August 24; Mexico, San Mateo, August 7; Idaho, Meridian, July 23, and Big Lost River, July 25; Wyoming, Fort Bridger, July 13; Oklahoma, Old Greer County, July 19; Arizona, Tucson, August 16, and San Bernardino Ranch, August 24; Texas, Mobeetie, July 27, Beaumont, August 5, Rockport, August 12, Hereford, August 18, and Padre Island, August 21; Massachusetts, Monomoy Island, July 19, and Nahant, August 4; New York, Mastic, July 4, and Freeport, July 16; South Carolina, Charleston, July 8; and Florida, James Island, July 20.
Late dates of fall departure are: Alaska, Craig, September 24, and St. Lazaria Island, September 29; British Columbia, Chilliwack, September 11, and Comox, September 26; Montana, Great Falls, September 4; New Mexico, Albuquerque, October 5; Massachusetts, North Truro, September 2, and Harvard, September 8; New York, Chateaugay, September 13, Amityville, September 17, and Long Beach, October 12; New Jersey, Cape May County, September 14; District of Columbia, Anacostia River, September 25; and Virginia, Four-mile Run, September 11.
Casual records.—Casual occurrences of the western sandpiper must, of course, be based upon specimen evidence, as this species is easily confused with the semipalmated sandpiper. For this reason several records are considered doubtful, while in other regions it may be more numerous than is now known. One was taken August 21, 1907, at Beaver, Pennsylvania, while two were collected at Burlington, Iowa, on October 15, 1895, and one at Columbus, Ohio, on September 12, 1925.
Egg dates.—Alaska: 159 records, May 23 to July 7: 80 records, May 29 to June 15.