Friedmann (1929) regards the worm-eating warbler as a “rather uncommonly imposed upon species” by the eastern cowbird. “Twenty-one definite records, and as many more indefinite ones have come to my notice.”
Winter.—Dr. Alexander F. Skutch contributes the following: "Widely distributed as a winter resident in Central America, the worm-eating warbler appears to be everywhere very rare. It occurs from Guatemala to Panamá on both coasts, and upward in the mountains to at least 5,000 feet. On February 26, 1935, I found one in the forest on Barro Colorado Island, Canal Zone, which appears to represent a slight southward extension of the known range. I have recorded this rare visitant from every part of Central America below 6,000 feet in which I have made an extended sojourn during the months of the northern winter, yet only one or two in each locality, except on the Finca Mocá on the Pacific slope of Guatemala at 3,000 feet above sea-level, where in one day—January 21, 1935—I saw three. The worm-eating warbler is found in the Tropics beneath dense thickets or in the undergrowth of the forest, usually near the ground; but at times one will rise to the lower branches of the trees to investigate curled dead leaves caught up among them. It is solitary rather than social in its habits.
“The records of the occurrence of this warbler in Central America are too few to indicate clearly the dates of its arrival and departure. I found one at Tela, Honduras, on August 19, 1930; but the next early record is for October 14, at the same locality. Griscom quotes a record by Dearborn for the occurrence of this warbler at Patulul, Guatemala, on April 2; but except for this, the latest record I have seen is from El General, Costa Rica, March 11, 1939.”
DISTRIBUTION
Range.—Eastern United States to Panamá.
Breeding range.—The worm-eating warbler breeds north to northeastern Kansas (Lawrence); possibly central southern Nebraska (Red Cloud); probably south-central Iowa (Des Moines); probably southern Wisconsin (Wyalusing, Madison, and Milwaukee); northeastern Illinois (Hinsdale); southern Indiana (Terre Haute, Bloomington, and Indianapolis); central Ohio (Columbus, East Liverpool, and possibly Cleveland); southern New York (Penn Yan and Albany), and southern Connecticut (New Haven and Saybrook). It has been found in summer north to London, Ontario; Northampton, Ipswich, and North Eastham, Massachusetts. East to Connecticut (Saybrook); Long Island (Newtown); northern New Jersey (Elizabeth and Morristown); eastern Pennsylvania (Norristown and Philadelphia); northern Delaware (Wilmington); central Maryland (Baltimore; rarely east of Chesapeake Bay); eastern Virginia (Cobham and Dismal Swamp); central North Carolina (Chapel Hill and Statesville); northwestern South Carolina (Caesars Head, Mount Pinnacle, and Sassafras Mountain); and northern Georgia (Brasstown Bald and Atlanta). South to northern Georgia (Atlanta); central Tennessee (Nashville and Wildersville); northern Arkansas (Newport and Winslow); and, occasionally, extreme northern Texas (Bowie County and Gainesville). West to northern Texas (Gainesville); northeastern Oklahoma (Jay); and eastern Kansas (Lawrence). It has been recorded in summer, but with no evidence of breeding, at Red Cloud, Nebr., and at London and Vineland Station, Ontario.
Winter range.—In winter the worm-eating warbler is found north to southern Tamaulipas (Altamira); northern Florida, casually (Blue Springs and Amelia Island), and the Bahamas (Abaco, Nassau, and Great Inago). East to the Bahamas (Great Inago); Jamaica and central Panamá (Río Chepo). South to Panamá (Río Chepo, Barro Colorado, and Chiriquí). West to western Panamá (Chiriquí); Costa Rica (Escasú and Volcán Tonorio); El Salvador (Mount Cacaguatique); Guatemala (Dueñas, Patulul, and Naranjo); southern Chiapas (Huehuetán); western Veracruz (Jalapa); Hidalgo (Pachuca); and southern Tamaulipas (Altamira).
Migration.—Late dates of spring departure are: Panamá—Darién March 16. Costa Rica—El General, March 19. El Salvador—Barra de Santiago, April 8. Guatemala—Patulul, April 2. Yucatán—Mérida, April 9. Cuba—Habana, May 1. Bahamas—Abaco, April 29. Florida—Seven Oaks, May 14. Georgia—Cumberland, May 7. Alabama—Barachias, May 1. Mississippi—Biloxi, April 27. Louisiana—Avery Island, April 23.
Early dates of spring arrival are: Florida—Pensacola, March 26. Georgia—Savannah, April 4. South Carolina—Mount Pleasant, April 7. North Carolina—Bat Cave, April 16. Virginia—Richmond, April 19. West Virginia—Morgantown, April 4. District of Columbia—Washington, April 21. Pennsylvania—Beaver, April 29. New York—Jones Beach, April 20. Louisiana—Grand Isle, April 3. Mississippi—Bay St. Louis, April 5. Tennessee—Chattanooga, April 15. Kentucky—Bowling Green, April 3. Indiana—Brookville, April 17. Ohio—Columbus, April 18. Texas—Brownsville, March 29. Missouri—St. Louis, April 15. Iowa—Keokuk, April 21.
Late dates of fall departure are: Missouri—St. Louis, September 20. Ohio—Austinburg, September 23. Kentucky—Middlesboro, September 27. Tennessee—Athens, October 5. Mississippi—Biloxi, October 11. Louisiana—Monroe, September 30. New York—Balston, September 23. Pennsylvania—Atglen, October 10. District of Columbia—Washington, September 13. West Virginia—Bluefield, September 19. Virginia—Salem, October 24. North Carolina—Andrews, October 11; Raleigh, November 3. South Carolina—Charleston, October 11. Georgia—Atlanta, October 10. Florida—Fernandina, October 3.