Part 43

Snakes sometimes destroy the young, as related above; squirrels, blue jays, and other predatory mammals and birds rob the nests; and the adults must always be on the alert to escape the many enemies that prey on all small birds.

Harold S. Peters (1936) records only one louse, Philopterus subflavescens (Geof.), as an external parasite on the eastern yellow warbler.

Fall.--The striking feature of the fall migration of the eastern yellow warbler is its earliness. The birds begin to move away from their nesting haunts as soon as the young are able to take care of themselves, and the southward migration is well under way before midsummer. Smith (1943) says that, in Vermont, "during many seasons, the species is not seen later than July. Departure dates for local summer residents range from July 15 to the 30th. Later records occur between August 18 and September 9th." These later records are probably for birds from farther north. There seems to be a wide spread between the times that the earliest and latest birds leave.

Dr. L. H. Walkinshaw writes to me: "To me it is interesting how soon after nesting has been completed these warblers disappear. After July 10, it is very hard to find one of the species here in Michigan, and after August 10, almost impossible. It does stay some in certain good feeding areas, but the majority have left long before August." According to Milton B. Trautman (1940), the migration in Ohio begins early in July, reaches its height during the first half of August, and only stragglers are seen after September 10.

Arthur T. Wayne (1910) says that, in South Carolina--

the Yellow Warbler is positively uncommon during the spring migrations, but exceedingly abundant in summer and autumn. * * * By July 4, the return migration takes place and a few young birds arrive, but it is not until the 10th or 15th that they are common. * * * The habits of the birds are entirely changed, however, in summer and autumn, for then they frequent the cotton fields, as well as lands which have been planted with peas for forage. It is also not unusual in autumn to see as many as twenty or more of these little birds far out in the salt marshes, where they find food in abundance. The species is so very abundant in late summer and autumn that it is not unusual to encounter hundreds of individuals in a few hours on plantations or in close proximity to salt water.

Prof. W. W. Cooke (1904) writes: "Though in migration the yellow warbler occurs in Florida as far south as Key West and is sometimes fairly common in northern Florida, the numbers that migrate through the southern part of the State must be very small, for not a bird passing north or south has been reported from any of the Florida lighthouses. The migration route of the yellow warblers that breed near the Atlantic coast is evidently southwest to northern Georgia and Alabama, and then across the Gulf of Mexico."

Perhaps the main flight from Florida and the other Gulf States is across the Gulf to Yucatán and then down through Central to South America, for there seem to be no records for Cuba for the eastern yellow warbler. There is a regular migration along the coast of Texas. Dickey and van Rossem (1938) say that "the eastern yellow warbler migrates through El Salvador in fair numbers, but no specimens were taken at any time during the winter. In the fall, particularly, great numbers are in evidence. The first arrivals reached Lake Olomega on August 1, but the main body did not begin to drift through until about the middle of that month."

Frederick C. Lincoln (1939) remarks: "Redstarts and Yellow Warblers, doubtless the more southern breeders in each case, have been seen returning southward on the northern coast of South America just about the time that the earliest of those breeding in the North have reached Florida on their way to winter quarters."

Winter.--Dr. Alexander F. Skutch contributes the following winter notes: "This morning as I sat at breakfast a yellow warbler flitted among the shrubbery outside the window. Here in Central America, through 8 or 9 months out of the 12, this well-known bird occupies the same place in dooryard, garden, hedgerow and scrubby pasture as during its briefer sojourn in the more northerly regions where it nests. None of the resident warblers of Central America is quite so abundant and familiar about human dwellings. Everywhere it avoids the heavy forest and prefers the sunlight that floods the clearings made by man.

"It is one of the first of the visitants from the North to arrive in Central America, appearing in Guatemala as early as August 9, reaching Honduras by at least the fourteenth, Costa Rica by the seventeenth, and Panamá by the twenty-second of the month. These early dates are for the Caribbean lowlands, along which it appears to migrate. It arrives later on the Pacific side of the Isthmus, especially in Costa Rica, where it has not been recorded before August 24, at San José, and not until September 11 in the Térraba Valley, still more isolated from the Caribbean flyway by lofty, forested mountains. But by the end of September, it is well distributed as a winter resident over both coasts of Central America, and in the interior up to at least 5,000 feet, becoming rarer at the upper limit of its altitudinal range. Much above 5,000 feet it apparently does not winter; but it is occasionally seen in September in the high mountains as a bird of passage. A heat-loving warbler, it is most common in the lowlands where, in the plantation districts of northern Central America during the winter months, it is among the most abundant birds, whether resident or migratory.

"Although a number of wood warblers which winter in the Central American highlands are gregarious, those that center in the lowlands are typically solitary. In this, the yellow warbler is no exception. Each wintering bird appears to have its own territory, from which it attempts to drive others of its kind. Trespassers are scolded with insistent chips; or more rarely, soon after his arrival, a male will sing while defending his claim. Near San Miguel de Desamparados, Costa Rica (4,600 feet), on October 1, 1935, I made the following note: 'This morning, which for a change was bright and calm, I heard a yellow warbler singing in the low fig trees near the house. Upon going out to look, I found that there were two yellow warblers in the trees. One was trying to drive the other away; but the pursued always circled around and returned. I watched them for a long time; but this indecisive action continued without any change in the situation. In the intervals of the pursuit, the warblers (or at least one of them) would sing, but in a low and imperfect fashion, far inferior to the yellow warbler's summer song.' Again, on October 31: 'After the Wilson warbler, the most abundant winter visitor is the yellow warbler. The bird who on October 1 drove its competitor out of the fig trees beside the house still retains these trees and the surrounding Inga trees as its domain.'

"The yellow warbler sings far less while in Central America than many other wintering species. Exceptionally, one will be found singing profusely. In early October, 1934, I came upon such a bird among the coffee groves of a great plantation on the lower Pacific slope of Guatemala. His behavior was so far out of the ordinary that I am tempted to copy in full the notes I made upon it at the time: October 5--On the afternoon of my arrival at 'Dolores,' I went out for a walk through the coffee groves. From among the 'chalum' (Inga) trees which shaded the coffee bushes, I heard a bird's song which seemed to belong to a warbler; but I did not recognize it as the utterance of any species I knew. After searching for a time among the tree-tops, I spotted the singer, and was surprised to find him a yellow warbler. He was apparently a young bird, for he lacked the chestnut splashes along the sides which distinguish the mature males. He repeated over and over again his little song of four or five notes, which was so unlike the familiar song of the yellow warbler in the eastern United States that I did not at first recognize it; but once I had identified the singer, I realized that I was listening to a shortened and modified form of the typical song.

"As I stood watching and listening to this eccentric warbler, the rain clouds which had been gathering darkly in the west began to surrender their pent-up waters; and the sudden shower approached across the plantation with the roar of a myriad fat drops striking against the large leaves of the Ingas and the far larger ones of the bananas which shaded the plantation. I took refuge from the rain beneath the broad expanse of a banana leaf, which completely shielded me from the beating downpour. Soon the heavy shower exhausted itself; and I emerged from beneath my green roof. The warbler, who had taken shelter from the shower somewhere in the foliage above me, resumed his cheerful singing.

"'On the next two days, I passed by the spot where I had heard the warbler singing, on the way to and from my botanical collecting ground. Morning and afternoon, I heard the same voice in the same part of the coffee plantation, where the bird seemed to have fixed his residence.'

"Yellow warblers may sing in Central America in the spring as well as the fall. Last year, the male yellow warbler that wintered about my house in Costa Rica sang briefly in the early morning from April 12 to 24. After April 28, I saw no more of his kind in the vicinity.

"From November 1936 until February of the following year, a yellow warbler slept every night in a bush of Hibiscus mutabilis beside my cabin in Rivas, Costa Rica. He rested upon one of the long leaf-stalks, where the broad blades of the higher leaves formed a roof above him, but he was exposed on the sides and easily visible from the ground. He always slept alone.

"Early dates of fall arrival in Central America are: Guatemala--passim (Griscom), August 9; Sierra de Tecpán, 8,500 feet, September 4, 1933; Huehuetenango, 6,500 feet, September 11, 1934. Honduras--Tela, August 14, 1930. Costa Rica--Puerto Limón, August 17, 1935; San José (Cherrie), August 24; Cartago, September 6, 1938; Basin of El General, 2,000-3,000 feet, September 13, 1936 and September 11, 1942. Panamá--Canal Zone (Arbib and Loetscher), August 22, 1934.

"Late dates of spring departure are: [British Guiana (Beebe), April 10.] Panamá--Barro Colorado Island, April 23, 1935; Almirante, April 29, 1929. Costa Rica--Basin of El General, April 30, 1936, April 29, 1937, May 7, 1939, May 3, 1940, April 28, 1942; San José (Cherrie), May 11. Honduras--Tela, May 9, 1930. Guatemala--passim (Griscom), May 6; Los Amates, Motagua Valley, May 11, 1932."

Todd and Carriker (1922), reporting for the Santa Marta region of Colombia, say that the eastern yellow warbler is "a common winter resident throughout the whole of the lowlands and lower foothills, but rare above the coastal plain. It frequents shrubbery, open ground with scattering bushes, the low growth along the banks of streams and the sea-beach, etc.--the same kind of covert in general to which it is so partial in the breeding season."

DISTRIBUTION

Range.--North America, northern South America and the West Indies.

Breeding range.--The yellow warblers of North America breed =north= to north-central Alaska (Kobuk River and Fort Yukon); northern Yukon (Potato Creek, 20 miles above Old Crow River); northwestern Mackenzie (Richard Island, Fort Anderson, Lake St. Croix, and Oot-sing-gree-ay-Island, Great Slave Lake); northern Manitoba (Lac Du Brochet, Churchill, York Factory, and Severn House); and central Quebec and Labrador (Richmond Gulf, Grand Falls of the Hamilton River, probably Northwest River, and Cartwright). =East= to eastern Labrador (Cartwright); Newfoundland (St. Anthony, Twillingate, and St. John's); Nova Scotia (Cape Breton Island, Halifax, and Yarmouth); and the Atlantic coastal region south to eastern and central North Carolina (Pine Island, Lake Mattamuskeet, Raleigh, and Charlotte); central South Carolina (Columbia); and central Georgia (Augusta and Macon). =South= to central Georgia (Macon); central Alabama, rarely (Autaugaville); southern Arkansas (Monticello and Arkadelphia); northeastern Texas (Paris, Commerce, and Dallas); west-central Oklahoma (Fort Reno and Thomas); southern New Mexico (Roswell and Silver City); probably southwestern Texas (Fort Hancock and El Paso); northern Sonora (Moctezuma, Magdalena, and Colonia Indepencia); and northwestern Baja California (El Rosario). =West= to the Pacific coast from northern Baja California (El Rosario) to western Alaska (Frosty Peak, Alaska Peninsula; Nushagak, Hooper Bay, Saint Michael, and Kobuk River). Wandering birds have been collected at Icy Cape and Wainwright on the northwest coast of Alaska several hundred miles north of the northernmost breeding record.

Winter range.--The yellow warbler is found in winter =north= to southern Baja California (La Paz); Jalisco (La Barca); Morelos (Cuernavaca and Yautepec); southern Veracruz (Tlacotalpan); Yucatán (Tunkás); and Quintana Roo (Akumal); occasional or accidental in winter near Brownsville, Tex. =East= to Quintana Roo (Akumal); Honduras (Tela and Ceiba); Nicaragua (Bluefields); Panamá (Almirante and the Canal Zone); Venezuela (Trinidad Island); British Guiana (Georgetown and the Berbice River); Surinam (Paramaribo); Cayenne (Cayenne and Approuague); and northeastern Brazil (Chaves). =South= to northern Brazil (Chaves, and Bôa Vista on the Rio Branco) and central Perú (La Merced). =West= to central western Perú (La Merced); western Ecuador (Guayaquil, Chones, and Esmeraldas); western Colombia (Condoto, Medellín, and Turbo); western Costa Rica (El General, San José, and Bolson); El Salvador (Puerto del Triunfo); western Guatemala (San José and Matzantinango); Chiapas (Huehuetán); Guerrero (Coyuca); Colima (Manzanillo); and southern Baja California (La Paz).

The range as outlined is divided into several subspecies or geographic races. The Newfoundland warbler (D. p. amnicola) breeds from central western Alaska south to central British Columbia, central Alberta, Saskatchewan and Manitoba, central Ontario and Quebec northward and east to Newfoundland; the Alaska yellow warbler (D. p. rubiginosa) breeds in the coastal region of southern Alaska; the Rocky Mountain yellow warbler (D. p. morcomi) breeds from southern British Columbia and Washington east through the Rocky Mountains south to northern Nevada, northern Utah and northern New Mexico; the California yellow warbler (D. p. brewsteri) breeds west of the Sierras in Oregon and California; the Sonora yellow warbler (D. p. sonorana) breeds from southeastern California, southern Nevada, and southern New Mexico to northwestern Mexico and western Texas; the eastern yellow warbler (D. p. aestiva) breeds from southern Canada east of the Rocky Mountains southward. The Cuban golden warbler (D. p. gundlachi) which is resident in Cuba, the Isle of Pines, and adjacent Cays has been found nesting on Bay Key, Fla. The mangrove, or "golden," yellow warbler (D. p. castaneiceps) breeds on both coasts of Baja California from about latitude 27° 14´ N. (San Lucas) southward; and on the west coast of Mexico from southern Sonora (Guaymas) south to Nayarit (San Blas). (Apparently it is only slightly migratory, if at all.)

Migration.--Early dates of spring departure are: Perú--Iquitos, March 11. British Guiana--Abary River, March 25. Venezuela--Rancho Grande, April 8. Colombia--Santa Marta Region, May 1. Panamá--Canal Zone, May 12. Costa Rica--San José, May 11. El Salvador--Chilata, April 24. Guatemala--Quiriguá, May 11. Honduras--Tela, May 9. Mexico--Tabasco, Balancán, May 11; Nuevo León, Montemorelos, May 21. Florida--Seven Oaks, May 27. Mississippi--Deer Island, May 25. Louisiana--Chenier au Tigre, May 21. Texas--Kerrville, May 31.

Early dates of spring arrival are: Florida--Pensacola, April 6. Georgia, Athens, April 7. South Carolina--Charleston, April 3. North Carolina--Windsor, April 4. Virginia--Lawrenceville, April 13. District of Columbia--Washington, April 2. Pennsylvania--Wayne, April 4. New York--New York, April 19. Massachusetts--Taunton, April 24. Vermont--Burlington, April 28. Maine--Portland, May 2. New Brunswick--Scotch Lake, May 1. Nova Scotia--Wolfville, May 8. Quebec--East Sherbrooke, May 6. Prince Edward Island--North River, May 6. Newfoundland--St. Anthony, June 5. Louisiana--Avery Island, March 23. Mississippi--Shell Mound, April 1. Arkansas--Tillar, April 5. Kentucky--Eubank, April 12. Indiana--Richmond, April 14. Ohio--Oberlin, April 12. Michigan--Ann Arbor, April 19. Ontario--London, April 20. Missouri--St. Louis, April 15. Iowa--Cedar Rapids, April 20. Wisconsin--Reedsburg--April 27. Minnesota--Minneapolis, April 27. Texas--Victoria, March 28. Oklahoma--Stillwater, April 16. Kansas--Topeka, April 16. Nebraska--Red Cloud, April 21. South Dakota--Faulkton, April 22. Manitoba--Aweme, April 30. Saskatchewan--Regina, May 4. Arizona--Fort Lowell, March 19. New Mexico--Albuquerque, April 24. Utah--Provo, April 25. Colorado--Littleton, April 23. Montana--Fortine, May 1. Alberta--Camrose, May 3. Mackenzie--Simpson, May 21. California--Diablo, March 12. Oregon--Portland, April 17. Washington--Camas, April 5. British Columbia--Comox, April 25; Atlin, May 15.

Late dates of fall departure are: Alaska--Ketchikan, September 6. British Columbia--Atlin, August 26; Chilliwack, September 9. Washington--Destruction Island, September 23. Oregon--Newport, September 18. California--Berkeley, October 10. Alberta--Edmonton, September 1. Montana--Great Falls, September 25. Wyoming--Yellowstone National Park, September 21. Colorado--Fort Morgan, October 2. Arizona--Organ Pipe Cactus National Monument, October 17. Saskatchewan--East End, September 5. Manitoba--Oak Lake, September 18. North Dakota--Fargo, September 19. South Dakota--Aberdeen, September 20. Kansas--Hays, September 23. Texas--Somerset, October 8. Minnesota--Lanesboro, September 10. Wisconsin--Milwaukee, September 20. Iowa--Marshalltown, September 26. Missouri--Bolivar, October 26. Michigan--Grand Rapids, October 8. Ontario--Ottawa, September 29. Ohio--Cleveland, September 30. Illinois--Chicago, September 29. Kentucky--Hickman, September 23. Mississippi--Gulfport, October 20. Louisiana--New Orleans, October 27. Newfoundland--Tompkins, September 9. Quebec--Montreal, September 3. New Brunswick--St. John, September 2. Nova Scotia--Yarmouth, September 11. Maine--Winthrop, September 23. Vermont--St. Johnsbury, September 21. Massachusetts--Stockbridge, October 1. New York--Rochester, October 30. Pennsylvania--Berwyn, October 7. District of Columbia--Washington, October 12. Virginia--Lexington, October 10. South Carolina--Charleston, October 10. Georgia--Milledgeville, October 27. Florida--Fort Myers, October 25.