We soon learn to identify their rather jerky flight as they rise from the bushes, and with a series of short wing flips turn now to the right, now to the left, in their zigzag progress, rising somewhat with the beats, and falling in the intervals. Sometimes a bird will go but a short distance, flitting from bush to bush, while others will climb higher and higher in the air, drifting in their jerky way across the sky like wind-blown leaves.* * *As soon as a Myrtlebird alights on a bush there is a short, sharp flip of tin tail, not a seesaw action, but one involving the body as well, and as it comesto rest the head is drawn in and the plumage ruffled up making the outline more nearly globular, while the wings are dropped slightly so that their tips are a little below the base of the tail.
We soon learn to identify their rather jerky flight as they rise from the bushes, and with a series of short wing flips turn now to the right, now to the left, in their zigzag progress, rising somewhat with the beats, and falling in the intervals. Sometimes a bird will go but a short distance, flitting from bush to bush, while others will climb higher and higher in the air, drifting in their jerky way across the sky like wind-blown leaves.* * *
As soon as a Myrtlebird alights on a bush there is a short, sharp flip of tin tail, not a seesaw action, but one involving the body as well, and as it comesto rest the head is drawn in and the plumage ruffled up making the outline more nearly globular, while the wings are dropped slightly so that their tips are a little below the base of the tail.
Francis H. Allen has sent me the following notes on the behavior of this species: “Aug. 27, 1915, Mt. Sunapee, N. H. On the summit of the mountain an immature myrtle warbler, very tame, flitted and hopped about on the ground, over moss and rocks, and in bushes and trees, feeding industriously on small insects. It seemed to pay no attention to my companion and me, and at one time hopped between us when we stood about 6 feet apart, and came within 2 feet of my outstretched hand as I held a crumb out towards it. I followed it about a little and found it quite fearless, except when I made a sudden movement. The bird could fly well and seemed perfectly well able to take care of itself.
“July 5, 1931, Mt. Whiteface, N. H. One or more were seen flying up fifty or a hundred feet above the tops of the low spruces and darting about up there after insects—doubtless the black flies which were abundant on the summit.
“Oct. 25, 1941, Plymouth, Mass. A sizable flock were feeding actively, flying back and forth across the narrow Eel River, feeding among foliage, catching flies and eating bayberries. One came within 6 feet of me and calmly ate bayberry after bayberry.”
Voice.—Aretas A. Saunders contributes the following account of the songs: “The songs of the myrtle warbler show some differences from those heard from birds on migration or on the breeding grounds. The song in general is a series of short, rapid notes in a rather colorless simple, but musical quality. The number of notes, in my 41 records, varies from 7 to 21 and averages about 12. The songs heard on migration, however, average 11 while those on the breeding grounds average 14.
“The songs heard on migration are quite indefinite in form; the pitch rises and falls irregularly, and no two songs are much alike. An individual bird may sing many variations, each song it sings often being a little different from the others. The notes, however, are all about the same length and loudness, accented notes that stand out from the others being rare. This song shows indications of a somewhat primitive character.
“The song on the breeding grounds is somewhat more definite; the notes are often joined in 2-note phrases, the first note of each phrase higher in pitch than the second and each phrase successively higher, so that the song trends upward in pitch. This is true of 10 of my 13 records of the song on the breeding grounds in the Adirondacks. The other 3 have a slight downward trend. In addition to the more regular form, these songs have a somewhat brighter, livelier, and more musical sound than those heard on migration.
“Songs of this species vary from 1 to 24⁄5seconds in length. There are usually about seven notes per second. Only 3 of my records show any irregularity in the time of the notes, that is having some notes that are shorter or longer than the others. Pitch of the songs varies from F‴ to E‴´, a half tone less than an octave. Single songs vary from one to four and a half tones, averaging about two and a half tones; only 5 records are greater in range, and only 16 are less, nearly half of the records having the average range.
“Since the myrtle warbler winters in Connecticut, I am able to get the first dates of singing. In 30 years of records the average date is April 13; the earliest April 2, 1923, and the latest April 25, 1920. In the Adirondacks the last date of singing noted was July 31, 1926.
“The call-note,tchick, is louder than in most warblers. I found it pitched on D″. Another note is a faintertseet tseet, usually doubled and pitched on F-sharp‴.”
Francis H. Allen (MS.) describes the song in a different way as follows:
“The only syllabifications I find in my notes are of a bird heard at West Bridgewater, Vt., June 19, 1907, which sangwhee whee whee whee whee whee whee whee hew hew, sometimes with three or even fourhewsat the end and sometimes with only one; and one of a bird at South Tamworth, N. H., July 23, 1942, whose song consisted of two trills,ching ching ching ching ching weedle weedle weet.
“The ordinary call-note is a hoarsechep, easily distinguished from the call of any other New England warbler. I have also heard occasionally a slighttsiportsit, suggesting a chickadee. The feeding call of the young out of the nest is a rapid succession of several explosivechipsorpitswith a rolling quality—a sort of chatter or chippering.”
On June 7, 1900, in Washington County, Maine, I recorded the song of the myrtle warbler aswheedle wheedle wheedle wheedle wheedle, repeated five to seven times so rapidly as to be hard to count and all on one key, usually ending abruptly but occasionally in a little trill.
Few writers have accorded the song of the myrtle warbler much praise, but Bradford Torrey (1885) pays it this tribute: “For music to be heard constantly, right under one’s window, it could scarcely be improved: sweet, brief, and remarkably unobstrusive, without sharpness or emphasis; a trill not altogether unlike the pine-creeping warbler’s, but less matter-of-fact and business-like. I used to listen to it before I rose in the morning, and it was to be heard at intervals all day long.”
Field marks.—The male myrtle warbler in spring plumage is easily recognized at a considerable distance in its blue-gray, black, and white plumage, offset by conspicuous patches of bright yellow on rump, sides, and crown, and by the black sides and cheeks. The female ismuch duller and browner, the yellow being less conspicuous and the black cheeks lacking. Young birds and fall adults are much like the female, but the yellow rump, showing plainly as the bird flies away from the observer, will distinguish the species at any season or age.
Enemies.—So much of the breeding range of the myrtle warbler is beyond the normal breeding range of the cowbirds that, until recently, it was supposed to be largely free from the imposition of this parasite. When Dr. Friedmann (1929) published his book on the cowbirds he had only three records of such molestation, but more have turned up since, particularly in the Middle West where the ranges of the two species overlap considerably. Dr. Paul Harrington writes to me from Toronto: “Sixty-five percent of the nests examined contained eggs or young of the cowbird; it would not be exaggerating to say that two-thirds of the initial nests are parasitized. The egg or eggs of the cowbird are often deposited before the nest is completed, leading to many a deserted nest. Twice I have found a cowbird’s egg imbedded, as so often happens in the yellow warbler’s nest, but in both cases yet another was in the nest with the owner’s. Twelve percent of the nests with eggs of the cowbird were deserted, but none in which the owner’s eggs were also present. Generally but one of the parasite’s eggs was found, occasionally two and rarely three.”
Dr. F. A. E. Starr says in his notes from Ontario: “Occasionally, when a cowbird usurps a nest, the birds continue building till the cowbird’s egg is imbedded. This is all in vain, however, as out of 30 nests, I have yet to find one which did not contain from one to three eggs of the cowbird.” And A. D. Henderson mentions in his notes from Belvedere, Alberta, a nest that held five eggs of the myrtle warbler and one egg of the Nevada cowbird, and another nestful consisting of four eggs of the warbler and two of the cowbird. Probably very few young of the warbler are likely to survive in nests with young cowbirds, which means that this parasite must seriously interfere with the normal increase in the warbler population.
Harold S. Peters (1936) lists two lice, two flies, and two mites as external parasites on the myrtle warbler.
Fall.—The myrtle warbler is one of the latest of its family to move southward and is also one of the most leisurely in migration; the migration covers practically the whole of September and October and much of November, the earliest arrivals sometimes reaching the Gulf States before the last ones have left Canada. Abundant in the spring, it is much more so in the fall, when it can often be seen in enormous numbers. As the birds drift along southward, many stop along the way where food is abundant and some spend the winter at no great distance from the southern limits of the breeding range. In Massachusetts, we usually look for them during the latter half of Septemberor during those golden October days when woods are ablaze with the gorgeous autumn colors. As we stroll along the sunny side of the woods on some bright morning after a frosty night, the air is full of pleasing bird music. The robins, now wild woodland birds, are twittering or uttering their wild autumn calls as they drift through the trees; the white-throated and the song sparrows, from the brushy thickets below, give forth their faint, sweet notes like soft echoes of their springtime songs; and the myrtle warblers mingle their distinctive call-notes with these other voices as they glean for aphids on the birches. In the open grassy fields and weed patches, too, we find many myrtle warblers associated with the scattered flocks of juncos and field and chipping sparrows, feeding on the ground. And later in the fall, we find them in the bayberry patches near the seacoast, or even on the salt marshes or among the sand dunes with the Ipswich and savanna sparrows.
Southward along the Atlantic coast the flight is heavy; Dr. Stone (1937) says that, at Cape May, N. J., “on October 13, 1913, Julian Potter encountered a great flight of Myrtle Warblers which he estimated at 3,000.* * *October 31, 1920, was a characteristic Myrtle Warbler day. All day long they were present in abundance. The air seemed full of them wherever one went. Thousands were flittering here and there in the dense growth of rusty Indian grass (Andropogon), in the bayberry thickets, in pine woods and in dune thickets.”
From their breeding grounds in the northern interior these warblers continue to drift southward during October, not in compact flocks but straggling in a continuous stream, some alighting while others are moving on. In Ohio, according to Trautman (1940), “the numbers continued to increase rapidly until approximately October 5. Between October 5 and 20 the species was more numerous over the entire land area than it was at any other season, and thousands were daily present. It was particularly abundant on Cranberry Island, where it fed upon insects, cranberries, poison sumac, and other berries. On several occasions an estimated number between 1000 and 1200 individuals was seen within an hour on this island. After October 20 there was a rather gradual decline in numbers. By November 1, comparatively few remained, and in some years the birds had disappeared.”
Winter.—The myrtle warbler winters abundantly throughout the southern half of the United States east of the Great Plains, commonly as far north as southeastern Kansas, southern Illinois, southern Indiana and northern New Jersey, and less commonly or rarely and irregularly farther north. It is the only one of the wood warblersthat is hardy enough to brave the rigors of our northern winters amid ice and snow and sometimes zero temperatures.
Robert Ridgway (1889) writing of its winter habits in southern Illinois, says:
It may often be sees in midwinter, when the ground is covered with snow, in the door-yards along with Snowbirds (Junco hyemalis), Tree Sparrows, and other familiar species, gleaning bread crumbs from the door-steps, or hunting for spiders or other insect tidbits in the nooks of the garden fence or the crevices in the bark of trees; and at evening, flying in considerable companies, to the sheltering branches of the thickest tree tops (preferably evergreens), where they pass the night. Not infrequently, however, they roost in odd nooks and crannies about the buildings, or even in holes in the straw- or hay-stacks, in the barn-yard. A favorite food of this species are the berries of the Poison-vine (Rhus toxicodendron), and during the early part of winter large numbers of them may be seen wherever vines of this species are abundant.
What few myrtle warblers remain in southern Massachusetts are usually to be found in situations similar to those frequented in late fall, especially near the coast where there is a good supply of bayberries and other berries. When this supply is exhausted they move elsewhere, though they can subsist to some extent on the seeds of the pitch pine, on grass seed, and on various weed seeds. In New Jersey, they are found in similar situations. Farther south they are abundant inland as well as on the coast, living in all kinds of environments—old fields, cultivated lands, thickets, brushy borders of the woodlands, and in woods of scrub oaks and pine. They are common to abundant on both coasts of Florida and in the interior and often come into the orange groves, to feed on the fallen oranges. A. H. Howell (1932) says: “Not infrequently they may be found in numbers on the Gulf beaches, or in reeds in the salt marshes of the coast or in the Everglades. They are partial to the borders of streams or sloughs, and sometimes venture out on the floating vegetation in rivers or lakes.”
The following is contributed by Dr. Alexander F. Skutch: “In December, 1932, it was vividly brought home to me how widely the myrtle warblers are spread over the earth during the winter months, and in what varied climates they dwell. On the ninth, a clear, cold, winter day, I met a small party of these yellow-rumped birds in a barren field at the edge of a woods in Maryland. On the twenty-fourth, I watched them fly above the tatters of melting snow in New Jersey, within view of the skyscrapers of New York. That afternoon I embarked upon a ship, and a week later arrived upon a banana plantation in Guatemala, where the air was balmy and the landscape vividly green, where snow and bleak winds seemed to belong to another world. Yet here, too, were myrtle warblers, hundreds of them, feeding in the open pastures and along the roadways, wherever the vegetation was not too dense, then rising up in compact flocks, wheelingand dropping together, moving always as though actuated by a true group spirit. During three days on that plantation, I met 23 kinds of winter visitants from the North; yet the myrtle warbler appeared to be the most abundant of them all: certainly, I saw far more of them than of any other migratory bird; yet this was in part because they foraged in more exposed places. Of all the warblers I found here, this was the only species that moved in flocks; for most of the wood warblers that winter in the Central American lowlands are strict individualists. It is also significant that of all the 23 species of wintering birds, this, the most abundant in December, was the only one then common that I had not recorded from February to June of the same year, when I passed 4 months studying the birds on that same plantation.
“Although it has been recorded from Central American localities as early as October and as late as April, the myrtle warbler is certainly most abundant as a winter visitant from November to March. All my own records from points in Guatemala, Honduras, and Costa Rica fall within these 5 months. It arrives later and departs earlier than warblers less tolerant of cold.
“The myrtle warbler winters in a variety of situations. At Puerto Castilla, on the northern coast of Honduras, I found these warblers abundant at the end of January, 1931. Here they foraged upon the lawns between the cottages, hopping rather than walking like water-thrushes, and when alarmed flew up to rest upon the broad fronds of the coconut palms that lined the sandy beach. At the other extreme, I have found them in mountain pastures, rarely as high as 8,500 feet above sea level. In the highlands, this bird is likely to be confused with the Audubon warbler, from the mountains of western United States, in similar dull winter attire. But the Audubon warbler, even at this season, wears five patches of yellow—on the crown, throat, both sides and rump—while the myrtle warbler shows only four, lacking that on the throat. The presence or absence of yellow on the throat is a distinguishing feature.
“At the end of December, 1937, I found myrtle warblers abundant in the vicinity of Buenos Aires de Osa, a hamlet in the lower Térraba Valley of Costa Rica, of interest to the bird-watcher because, although lying in a region covered by the heaviest lowland forest, it is surrounded by extensive open savannas which support a rather different bird-life. Here fork-tailed flycatchers were also abundant, roosting by night in some orange trees behind the padre’s house, by day spreading in small flocks over the savannas, where they perched in the low bushes, only a few feet above the ground, and darted down to snatch up the insects they descried. It was surprising to find the myrtle warblers associating intimately with the flycatchers; just as, in theGuatemalan highlands, I had found Audubon’s warblers flocking with bluebirds. The myrtle warblers not only foraged about the bushes which served the flycatchers as watch-towers; but the two kinds of birds, so dissimilar in size and habits, changed their feeding grounds together. While I sometimes found the warblers alone, I saw them in company with the fork-tailed flycatchers too often for the association to be looked upon as accidental. I could not discover that either warbler or flycatcher derived any material advantage from the presence of the other. It seemed to be a case of pure socialibility.
“Central American dates are: Guatemala—Motagua Valley, near Los Amates, December 31, 1932; Sierra de Tecpán, March 16, 1933; Finca Mocá, January 20-26, 1935; Nebaj (Griscom), April 27; La Primavera (Griscom), April 8. Honduras—Puerto Castilla, January 27, 1931; Tela (Peters), March 17. Costa Rica—Vara Blanca, December 13, 1937, to February 28, 1938; Guayabo (Ridgway and Zeledón), March 18; Carrillo (Underwood), October 2; Guacimo (Carriker), December 4; Las Cañas, Guanacaste, November 21, 1936; El General, January 12, 1936; Buenos Aires de Osa, December 24-30, 1937.”
DISTRIBUTION
Range.—North America.
Breeding range.—The myrtle warbler breedsnorthto northern Alaska (Kobuk River and timberline on the south slope of the Brooks Range); northern Yukon (La Pierre House); northern Mackenzie (Aklavik; Fort Anderson; MacTavish Bay, Bear Lake; Lake Hardisty, and Artillery Lake); northern Manitoba (Lac du Brochet, Cochrane River, and Churchill); northern Ontario (Moose Factory); southern Labrador (Grand Falls and Rigolet, possibly Nain and Okkak).Eastto eastern Labrador (Rigolet and Cartwright); Newfoundland (St. Anthony, Canada Bay, and St. John’s); and Nova Scotia (Cape Breton Island, Sable Island, Halifax, and Yarmouth).Southto southern Nova Scotia (Yarmouth); New Brunswick (Grand Manan); southern Maine (Gouldsboro, Deer Isle, Bath, and Auburn); New Hampshire (Concord); central and southern Massachusetts (Marlboro, Webster, and Pelham); southwestern Vermont (Bennington); northern New York (Falls Pond and Buffalo); rarely northeastern Pennsylvania (Pocono Lake); accidentally in northern Maryland (Havre de Grace); southern Ontario (London and Sarnia); northern Michigan (Crawford County and Douglas Lake); northern Wisconsin (Antigo, probably, Trout Lake, Namekagon Lake, and Superior); central Minnesota (St. Cloud, Brainerd, and Bemidji); southern Manitoba (Winnipeg and Aweme); central Saskatchewan (Flotten Lake and Prince Albert); central Alberta (Flagstaff, Camrose, Lobstick River, and Wipiti River); northern British Columbia(Fort St. John, Ingenika River, and Buckley Lake); and southern Alaska (Admiralty Island, Sitka, Seldovia, and Nushagak).Westto western Alaska (Nushagak, Russian Mission, St. Michael, and the Kobuk River).
Winter range.—The myrtle warbler winters in two discontinuous areas. The principal winter home isnorthto central Oklahoma (Oklahoma City); northern Arkansas (Winslow, Little Rock, and Helena); western Tennessee (Memphis); southern Illinois (Anna and Mount Carmel); southern Kentucky (Bowling Green); central Virginia (Lexington); District of Columbia (Washington); southeastern Pennsylvania (Philadelphia); northern New Jersey (Morristown and Elizabeth); southern Connecticut (New Haven); Rhode Island (Providence); and northeastern Massachusetts (Cape Ann). It also occurs in winter irregularlynorthto Holly, Colo.; Hays and Manhattan, Kan.; Madison, Wis.; Chicago, Ill.; Battle Creek and Rochester (one banded in January), Mich.; Rochester, N. Y.; and Portland, Maine.Eastto Massachusetts (Cape Ann) and along the Atlantic coast to Florida (Miami and Key West); the Bahama Islands (Little Abaco and Caicos); Dominican Republic (Puerto Plato and Sánchez); Puerto Rico (San Juan); St. Croix Island; and rarely, Antigua.Southto Antigua, northern Colombia, rare or accidental (Santa Marta region); and Panamá (Pearl Islands).Westto Panamá (Pearl Islands, Canal Zone, and Almirante); Costa Rica (El General and Guayabo); eastern Nicaragua (Greytown and the Río Escondido); northern Honduras (Puerto Castilla and Lancetilla); western Guatemala (Dueñas and Tecpán); eastern Oaxaca (Tehuantepec); Veracruz (Orizaba); Tamaulipas (Victoria); Nuevo León (Monterrey); southwestern Texas (mouth of the Pecos River, Camp Barkeley, Taylor County, and Fort Worth); and central Oklahoma (Oklahoma City).
The western winter range isnorthto central Western Oregon (Newport and Albany).Eastto western Oregon (Albany); central California (Marysville, Stockton, Mariposa County, Redlands, and Potholes); southern Arizona (Tucson and Tombstone); and southwestern Sonora (Guaymas).Southto southern Sonora.Westto western Sonora (Guaymas and the Colorado River delta); western California (San Clementi Island, Santa Barbara, San Francisco Bay region, and Eureka); and western Oregon (Coss Bay and Newport).
The species as outlined is divided into two subspecies or geographic races. The Alaska myrtle warbler (D. c. hooveri) breeds from western Alaska and northwestern Mackenzie to central Alberta and central British Columbia; the eastern myrtle warbler (D. c. coronata) from western Saskatchewan eastward.
Migration.—Late dates of spring departure from the winter home are: Costa Rica—Guayabo, March 18. El Salvador—Volcán de SanMiguel, March 22. Guatemala—Nebaj, April 27. Honduras—Lancetilla, March 17. Mexico—Valles, San Luis Potosí, May 2. Puerto Rico—Mayagüez, April 8. Haiti—Port-au-Prince, April 27. Cuba—Habana, April 28. Bahamas—New Providence, April 2. Florida—Pensacola, May 13. Alabama—Birmingham, May 8. Georgia—Atlanta, May 20. South Carolina—Greenwood, May 12. Louisiana—Mansfield, May 2. Mississippi—Oxford, May 8. Tennessee—Nashville, May 17. Arkansas—Helena, May 18. Texas—Bonham, May 6. Oklahoma—Norman, May 3.
Early dates of spring arrival are: New York—New York, April 1. Massachusetts—Lynn, April 11. Vermont—St. Johnsbury, April 12. Maine—Portland, April 6. New Brunswick—Scotch Lake, April 11. Nova Scotia—Yarmouth, April 11. Quebec—Hatley, April 22. Newfoundland—St. Anthony, April 25. Labrador—Cartwright, May 24. Illinois—Chicago, March 24. Indiana—Bloomington, March 26. Ohio—Youngstown, April 1. Ontario—Harrow, April 3. Michigan—Sault Ste. Marie, April 9. Missouri—Columbia, March 27. Iowa—Sigourney, April 3. Wisconsin—New London, April 1. Minnesota—Minneapolis, April 4. Kansas—Independence, April 7. Nebraska—Red Cloud, April 1. South Dakota—Brookings, April 7. North Dakota—Fargo, April 13. Manitoba—Aweme, April 12. Saskatchewan—Eastend, April 22. Mackenzie—Simpson, May 7. New Mexico—San Antonio, April 18. Colorado—Colorado Springs, April 17. Wyoming—Laramie, April 15. Montana—Kirby, April 29. Alberta—Glenevis, April 14. Washington—Seattle, March 14. British Columbia—Courtenay, March 31; Atlin, April 21. Yukon—Sheldon Lake, April 26. Alaska—Wrangell, April 29; Fairbanks, May 7.
Late dates of spring departure of transients are: District of Columbia—Washington, June 1. Pennsylvania—Warren, June 6. Illinois—Chicago, June 3. Indiana—Waterloo, June 3. Ohio—Oberlin, May 31. Missouri—Concordia, May 25. Iowa—Grinnell, June 1. Nebraska—Nenzel, May 27. North Dakota—Argusville, May 30. California—Red Bluff, May 3. Nevada—Quinn River Crossing, May 21. Washington—Tacoma, May 3.
Late dates of fall departure are: British Columbia—Atlin, September 19; Courtenay, October 14. Mackenzie—Nahami River, October 25. Wyoming—Laramie, November 25. Saskatchewan—Yorkton, October 14. Manitoba—Brandon, October 31. North Dakota—Argusville, November 15. South Dakota—Faulkton, November 15. Kansas—Lawrence, November 12. Minnesota—St. Paul, November 5. Wisconsin—Racine, November 16. Iowa—Wall Lake, November 15. Missouri—Kansas City, November 16. Illinois—Murphysboro, November 21. Michigan—Detroit, November 19. Indiana—Indianapolis, November 20. Ontario—Point Pelee, November 23. Ohio—Toledo,November 17. Newfoundland—Tompkins, October 4. Prince Edward Island—North River, October 15. Quebec—Kamouraska, November 9. New Brunswick—Saint John, November 4. Maine—Portland, November 9. New Hampshire—Durham, November 4. Massachusetts—Boston, November 27. New York—Brooklyn, November 22. Pennsylvania—Doylestown, November 29.
Early dates of fall arrival are: Washington—Bellingham, September 28. Oregon—Thurston, October 5. California—Eureka, October 12. Wyoming—Yellowstone Park, August 25. North Dakota—Fargo, September 8. South Dakota—September 15. Nebraska—Fairbury, September 30. Kansas—Lawrence, September 26. Oklahoma—Oklahoma City, October 12. Texas—Somerset, October 10. Iowa—Grinnell, September 6. Missouri—St Louis, September 17. Illinois—Chicago, August 31. Indiana—Hobart, September 2. Ohio—Austinburg, August 25. Kentucky—Bowling Green, September 14. Tennessee—Athens, October 3. Arkansas—Rogers, October 4. Louisiana—Monroe, September 26. Mississippi—Edwards, September 22. New York—Rhinebeck, August 31. Pennsylvania—Pittsburgh, September 8. District of Columbia—Washington, September 9. West Virginia—Bluefield, September 12. Virginia—Naruna, September 22. North Carolina—Mount Mitchell, September 30. South Carolina—Spartanburg, September 21. Georgia—Round Oak, October 10. Alabama—Anniston, October 8. Florida—New Smyrna, October 4. Bahamas—Cay Lobos, November 22. Cuba—Habana, November 17. Dominican Republic—San Juan, October 1. Puerto Rico—Mayagüez, December 14. Costa Rica—Carrillo, October 2.
Banding.—The myrtle warbler comes rather more readily than other warblers to banding traps, especially in winter, and so has yielded several records of migration and of longevity for return to the place of banding. A myrtle warbler banded at Elmhurst, Long Island, on October 19, 1936, was recovered on December 9, 1936, at Awensdaw, S. C. One banded on October 2, 1932, at Fargo, N. D., was found dead December 5, 1932, at Clarence, La. Another banded at Wilton, N. D., on September 25, 1939, was found in January 1940 at Leola, Ark. One banded on February 2, 1930, at Gastonia, N. C., was shot on December 25, 1930, at Kings Creek, Cherokee County, S. C.
A banding station at Thomasville, Ga., obtained several records indicative of the birds’ tendency to return to the same wintering place. Three birds banded in March 1920, were retrapped in February and March of 1921. One banded February 24, 1921, was retrapped February 5, 12, and 13, 1924, and found dead, apparently of starvation, on the fifteenth. A myrtle warbler banded on February 28, 1917, was retrapped in March 1920 and several times between March 1 and 17,1921. It was then at least 5 years old and had made four round trips to the breeding grounds.
Another myrtle warbler banded at Huntington, Long Island, on October 23, 1933, was killed February 1, 1940, at Dunbar, S. C.; it was then at least 61⁄2years old.
Casual records.—At least six specimens of the myrtle warbler have been collected in Greenland: Fiskenaes, May 21, 1841; Julianehaab, about 1847; Godhavn, July 31, 1878; Nanortalik, May 23, 1880; Agpamiut, in Sukkertoppen District, October 15, 1931; and Kangea, near Godthaab, October 28, 1937. A specimen was taken from the stomach of a white gyrfalcon October 7, 1929, killed near the Post on Southampton Island. Two specimens have been collected on the Arctic Coast of Alaska: one on June 3, 1898, at Point Tangent; and one June 4, 1930, near Point Barrow. A myrtle warbler was collected May 25, 1879, on the northeast coast of Siberia at latitude 67° N. At sea about 100 miles from Cape Hatteras, several myrtle warblers were noted on October 16 and 31, 1930.
Egg dates.—Maine: 16 records, May 26 to June 23; 10 records, June 11 to 20, indicating the height of the season.
New Brunswick: 10 records, June 5 to 28; 6 records, June 13 to 21.
Nova Scotia: 14 records, May 23 to June 21; 7 records, June 3 to 17 (Harris).
DENDROICA CORONATA HOOVERI McGregor
ALASKA MYRTLE WARBLER
HABITS
The Alaska myrtle warbler is another subspecies that was described many years ago but only recently admitted to the A. O. U. Check-List. Richard C. McGregor (1899) described this warbler, from specimens collected in California, as a western race and named it for his friend Theodore J. Hoover, who collected the type and placed his material at his disposal. He called itDendroica coronata hooveri, Hoover’s warbler. In his description of it he says that it is “in colors and markings likeDendroica coronata, but with wing and tail much longer.” His table of measurements shows that the wings of California males average .15 inch longer than those of eastern birds, and the tails .14 inch longer, less than1⁄6inch! Among the wing measurements of eastern males the individual variation is as great as the difference in his averages, the shortest measuring 2.80 and the longest 2.95 inches! It appears to be a quite finely drawn subspecies.
Dr. Oberholser (1938) says of it: “The Myrtle Warblers breeding in Alaska are recognizable as a western race of this species. They differ from the eastern bird in larger size and more solidly blackbreast in the male. The upper parts in winter plumage and in the young are also less rufescent than in the eastern bird.”
The breeding range of this race, so far as known, extends from northwestern Mackenzie to western Alaska, and southward to central British Columbia and central Alberta. It has been found in winter from California to southeastern Louisiana, in the southeastern United States, and in northern Baja California and in southern Veracruz, in Mexico. It may be commoner than is supposed, as it is recognizable only with specimens in hand.
Dr. Joseph Grinnell (1900) writes of its habits in northern Alaska:
Hoover’s Warblers were numerous summer residents of the timber tracts throughout the Kowak Valley from the delta eastward. In the latter part of August scattering companies were frequenting the spruce, birch and cottonwoods, among the foliage of which they were constantly searching, with oft-repeated ‘chits,’ just as are their habits in winter in California. The last observed, a straggling flock of six or eight, were seen in a patch of tall willows about sunset of August 30th. The following spring the arrival of Hoover’s Warblers was on May 22nd. They were already in pairs and the males were in full song. At this season they were confined exclusively to the heavier spruce woods. In the Kowak delta, on the 23rd of June, a set of five considerably-incubated eggs was secured. The nest was in a small spruce in a tract of larger growth, and only four feet above the ground. It is a rather loose structure of fine dry grass-blades, lined with ptarmigan feathers.
In the Atlin region of northern British Columbia, according to Mr. Swarth (1926), it is a common species, breeding mostly in the lowlands:
A nest with five fresh eggs (Mus. Vert. Zool. no. 1992) was taken by Brooks on June 15. It was in a slender spruce, one of a small thicket in a locality that is largely poplar grown, about forty feet from the ground and near the top of the tree. It rested on the twigs forming the terminal forks of a branch, about three feet from the trunk. The outer walls of the nest were built mostly of the shredded bark of the fire-weed stalks, with a little fire-weed ‘cotton,’ some coarse grass and small twigs, and several wing and tail feathers of a small bird. In the lining there was some horse hair, mountain sheep hair and a few soft feathers.Another nest, containing newly hatched young on June 28, was in a small jack pine in open woods on the shore of Lake Atlin.During the last week in August and the first week in September the southward exodus was at its height. Flocks of warblers, mostly this species, flitted rapidly through the poplar woods, and there was a constant stream of myrtle warblers making long flights overhead. The last one, a single bird, was seen September 19.
A nest with five fresh eggs (Mus. Vert. Zool. no. 1992) was taken by Brooks on June 15. It was in a slender spruce, one of a small thicket in a locality that is largely poplar grown, about forty feet from the ground and near the top of the tree. It rested on the twigs forming the terminal forks of a branch, about three feet from the trunk. The outer walls of the nest were built mostly of the shredded bark of the fire-weed stalks, with a little fire-weed ‘cotton,’ some coarse grass and small twigs, and several wing and tail feathers of a small bird. In the lining there was some horse hair, mountain sheep hair and a few soft feathers.
Another nest, containing newly hatched young on June 28, was in a small jack pine in open woods on the shore of Lake Atlin.
During the last week in August and the first week in September the southward exodus was at its height. Flocks of warblers, mostly this species, flitted rapidly through the poplar woods, and there was a constant stream of myrtle warblers making long flights overhead. The last one, a single bird, was seen September 19.
As the breeding ranges of Hoover’s warbler and Audubon’s warbler approach each other in British Columbia and may even overlap it would not be strange if hybrids between these two closely related species should occasionally turn up. Joseph Mailliard (1937) calls attention to a number of such hybrids between both forms ofcoronataandauduboni. And more recently, Fred M. Packard writes to me: “I have inspected skins in most of the major museums in America to detect these hybrids, and have been surprised at the number I have found. All but two were taken in the Rockies or farther west, so that presumably the subspecies concerned isD. c. hooveri.”
DENDROICA AUDUBONI (Townsend)
PACIFIC AUDUBON’S WARBLER
Plate 34
HABITS
The Pacific Audubon’s warbler is a handsome western species closely related to our familiar myrtle warbler, which to a large extent it replaces, and is much like it in behavior and appearance; but it has one more touch of color in its brilliant yellow throat, five spots of yellow instead of four, and it has more white in the wings and tail. Although its breeding range does not extend nearly as far north as that of the myrtle warbler, it extends farther south, and to considerably higher altitudes, breeding largely in the Canadian Zone among the pines, firs, and spruces. Including the range of the Rocky Mountain form (memorabilis), which has not yet been admitted to the A. O. U. Check-List, the type race breeds from central British Columbia, central Alberta, and west-central Saskatchewan southward to southern California, northern Arizona, New Mexico, and western Texas. Throughout most of this range it is widely distributed in the lowlands only during the winter, retiring to the mountains for the breeding season.
In the mountains of New Mexico it has been found breeding at altitudes of from 7,500 feet to over 11,000 feet. In Colorado it breeds at similar elevations and perhaps up to nearly 12,000 feet. In southern California, Dr. Joseph Grinnell (1908) found it breeding in the San Bernardino Mountains from 9,000 feet “almost to timber limit, 10,500 feet elevation, at least.* * *This was one of the most abundant birds of the San Bernardino mountains, and was widely distributed from the lower edge of the Transition zone up through the Boreal.” Grinnell and Storer (1924) write:
The Audubon Warbler is the most widely distributed and the most abundant of all the species of wood warblers found in the Yosemite region. It occurs in numbers throughout the main forested districts of the mountains during the summer season, and it frequents the deciduous trees and brush of the foothill and valley country in the winter time.Altitudinally its summer range extends from the beginning of the Transition Zone yellow pines on the west slope, at 3300 to 3500 feet, up through the lodgepole pines and other conifers of the Canadian and Hudsonian zones to the upper limit of unstunted trees at 10,000 feet or a little higher.* * *During the summer season the Audubon Warbler keeps mainly to coniferous trees, foraging from 10 to 50 feet or more above the ground. In the Transition Zone and part of the Canadian Zone it shares this habitat with the Hermit Warbler, but at the higher altitudes it is the only warbler present in the evergreen forest.
The Audubon Warbler is the most widely distributed and the most abundant of all the species of wood warblers found in the Yosemite region. It occurs in numbers throughout the main forested districts of the mountains during the summer season, and it frequents the deciduous trees and brush of the foothill and valley country in the winter time.
Altitudinally its summer range extends from the beginning of the Transition Zone yellow pines on the west slope, at 3300 to 3500 feet, up through the lodgepole pines and other conifers of the Canadian and Hudsonian zones to the upper limit of unstunted trees at 10,000 feet or a little higher.* * *
During the summer season the Audubon Warbler keeps mainly to coniferous trees, foraging from 10 to 50 feet or more above the ground. In the Transition Zone and part of the Canadian Zone it shares this habitat with the Hermit Warbler, but at the higher altitudes it is the only warbler present in the evergreen forest.
Farther north, in Mono County, Calif., James B. Dixon tells me that he found it nesting between 7,600 and 9,500 feet elevation. Referring to the Toyabe region in Nevada, Dr. Jean M. Linsdale (1938) found the Rocky Mountain form in a somewhat different environment: “In the mountains the area occupied by this warbler agreed fairly well with the area covered with trees. Individuals were seen most often in aspens, limber pines, birches, willows, and mountain mahoganies.” Angus M. Woodbury (MS.) says of the breeding range of the Rocky Mountain form in Utah: “It summers in altitudes ranging from about 7,000 to 10,000 feet and nests in almost any of the components of the forests in those altitudes; pine, fir, spruce, aspen, or oak.”
In Washington, Audubon’s warbler is common and well distributed from near sea level in the vicinity of Seattle and Tacoma up to about 8,000 feet in the mountains. Near Tacoma, D. E. Brown showed us some typical lowland haunts of this warbler in the so-called “prairie region.” On this smooth, flat land, a fine growth of firs and cedars was scattered about in the open; the two or three local species of firs were most abundant and were growing to perfection, being well branched down to the ground.
Spring.—There is a northward as well as an altitudinal migration in the spring. Samuel F. Rathbun says in his notes from Seattle: “Although the Audubon’s is of frequent if not regular occurrence during the winter, a migration of the bird through the region is to be noted each spring and fall.” Near Seattle the first birds are seen and their song is heard about March 10 to 15, and numbers are seen passing through up to the latter part of April. “By way of comparison, in the Lake Crescent section the first are seen about April 2, at the earliest, and after three weeks the last appear to have passed by, as the species performs its spring migration in a leisurely manner.” A later wave of migrants passes through Seattle between April 10 and 25, probably birds that nest farther north.
Migration is evident in Utah, for Woodbury (MS.) says: “In addition to its summer residence, it is a common migrant through the state, and a sparse winter resident, mainly at low altitudes. It migrates through the streamside and cultivated trees of the valleys, including shade trees and orchards. The migrations cover a period of about 6 weeks each in spring and fall, usually from about mid-April to the end of May and from mid-September to the end of October, but in different years the waves may be a little earlier or later.”
In California, there is a gradual exodus of Audubon’s warblers from the lowlands to the mountains during April and May. Mrs. Amelia S. Allen tells me that “by the end of April they have disappeared from the San Francisco Bay region.” And Swarth (1926b) says that in May, following the spring molt, “there is a gradual withdrawal of the birds to the higher mountains and to more northern latitudes.”
Audubon’s warbler occurs abundantly on the Huachuca Mountains, Ariz., but as a migrant only, during March, April, and May. Swarth (1904) writes:
Though distributed over all parts of the mountains, they were at all times more abundant in the higher pine region, than elsewhere; and on April 24, 1903, I found them particularly numerous along the divide of the mountains, evidently migrating. They could hardly be said to be in flocks on this occasion, for along the ridge, which runs almost due north and south, there was for several miles a continuous stream of Audubon Warblers travelling rapidly from tree to tree, always moving in a northerly direction; sometimes a dozen or more in one pine, and sometimes only two or three, but never stopping long and all moving in the same direction. Almost all that were seen on this occasion were high plumaged males, hardly half a dozen females being observed for the day.
This was about two weeks before the local breeding race(D. a. nigrifrons)might be expected to arrive.
Dr. Merrill (1888), at Fort Klamath, Oreg., found Audubon’s warblers “extremely abundant during the migrations. A few males were seen at Modoc Point on the 8th and 9th of April, and at the Fort on the 15th; by the 20th they were quite plentiful. A second ‘wave’ composed of both males and females, which latter had not previously been seen, arrived about the 4th of May, when they suddenly became more abundant than ever, bringingD. aestiva morcomiandH. lutescenswith them.”
Nesting.—The only two nests of Audubon’s warbler that I have seen were shown to me in Washington, near the State University at Seattle. The University is located on high land at the north end of Lake Washington, where the steep banks, sloping down to the lake, are heavily wooded with a mixed growth of large and small firs of at least two species, as well as cedars, alder trees, and maples. In the more open part of the woods I was shown, on April 29, 1911, a nest of this warbler placed about 30 feet from the ground on two small branches and against the trunk of a tall Douglas fir beside a woodland path. The other nest I saw in the previously described “prairie region” near Tacoma on May 14, 1911; it was placed only 9 feet from the ground but 10 feet out from the trunk of a dense Douglas fir growing in the open, and was well concealed in the thick foliage.
These nests were evidently typical for the region, according to Rathbun. He mentions in his notes two other nests. One, foundMay 2, 1909, on the east side of Lake Washington and along a road, was 30 feet from the ground in a small hemlock, near the extremity of one of the limbs and 7 feet out from the trunk. The other, found May 11, 1913, was in a small fir about 30 feet up and about 4 feet from the trunk on one of the lower limbs. “The nest is a very beautiful structure, constructed outwardly of very small twigs from the fir or hemlock, inside of which are placed smaller ones of the same character, with black rootlets, and lined with feathers, of which a quantity are used, and a few horsehairs. It is a compactly built affair.” Dawson and Bowles (1909) say that the nests are placed from 40 to 50 feet up, and usually measure 4 inches in width outside by 23⁄4in depth; and inside 2 by 11⁄2inches. They are made externally of such materials as fir twigs, weed tops, flower pedicels, rootlets, and catkins, and are heavily lined with feathers of various birds—including grouse, ptarmigan or domestic fowls—these feathers often curving upward and inward so as partially to conceal the eggs.
Dr. J. C. Merrill (1898) found a very different type of nesting near Fort Sherman, Idaho: “Here a majority of the nests I found were in deciduous trees and bushes, generally but a few feet from the ground. One was in a small rose bush growing at the edge of a cut bank overhanging a road where wagons daily passed close to it.* * *Occasionally one was seen in deep woods by the roadside near where hay had been brushed off a load on a passing wagon; this was utilized for the entire nest except lining, making a conspicuous yellow object in the dark green fir or pine in which it was placed.”
P. M. Silloway (1901) found a nest of Audubon’s warbler near Flathead Lake, Mont., that was 18 feet from the ground in a fork of a willow. “The fork containing the nest was in a main stem, upright, a number of feet below the leaf-bearing part of the tree, so that the nest was exposed quite fairly to view.” H. D. Minot (1880) found one at Seven Lakes, Colo., in an odd situation: “The nest, composed of shreds and feathers, with a few twigs without and hairs within, was built in a dead, bare spruce, about twenty feet from the ground, compressed between the trunk and a piece of bark that was attached beneath and upheld above, where a bough ran through a knot-hole, so compressed that the hollow measures 21⁄4x 13⁄4, and 11⁄2inches deep.” Dr. Chapman (1907) describes a nest from Estes Park, Colo., as “loosely constructed of weed-stems and tops, and strips of bark, lined with fine weeds and horse-hair.”
Mr. Woodbury (MS.) describes Utah nests as “compactly woven, cup-shaped structures, usually of fine grasses, plant fibers or shredded bark, lined with feathers or some substitute, and camouflaged with some fine stringy material holding bracts or other small particles in place.” He reports nests in such conifers as spruce, balsam, and ponderosa pine, and in aspen and oak.
J. Stuart Rowley writes to me: “In California, I have found several nests of this species in the San Bernardino Mountains and in the Mono County area in the northern part of the State. The nests I have found have all been beautifully made structures, securely fastened to small, low hanging branches of lodgepole pine, and placed about 10 to 12 feet from the ground.”
Dr. Grinnell (1908) records three nests, found in the San Bernardinos; one “was twenty feet above the ground in the thick foliage of a short drooping fir bough. It was compactly composed of weathered grasses, frayed-out plant fibres, and tail and wing feathers of juncos and other small birds. Internally it was thickly lined with mountain quail feathers, some of the chestnut-colored ones sticking above the rim conspicuously. This feather feature seems to be characteristic of Audubon warblers’ nests, as it was noticeably present in all that we saw.” Another nest was 25 feet from the ground in one of the lowest branches of a yellow pine. The third “was snugly tucked away in a small clump of mistletoe on an alder branch twelve feet above the ground.”
J. K. Jensen (1923) says of New Mexico nests: “The nests are usually placed on a horizontal limb of a pine or spruce, but also among dead twigs on the trunks of cottonwoods, and even in a cavity of some tree. All nests found were lined with a few feathers of Bluebirds and Long-crested Jay.”
Nests in tamarack, cedar, and birch have been reported by other collectors.
Eggs.—Audubon’s warbler lays from 3 to 5 eggs, almost always 4. They are ovate, tending toward short ovate, and are slightly glossy. They are grayish or creamy white, spotted and blotched with “raw umber,” “Brussels brown,” “argus brown,” and sometimes “auburn,” with underlying spots of “pale brownish drab,” “light brownish drab,” or “light mouse gray.” The markings are often confined to the large end, and frequently the drab undertones are in the majority, sometimes running together to form a cap, and this is relieved with a few superimposed spots or blotches of dark “argus brown,” or scattered small scrawls so dark as to appear almost black. The eggs generally are sparsely but rather boldly marked. The measurements of 50 eggs average 17.6 by 13.5 millimeters; the eggs showing the four extremes measure19.4by 14.0, 19.1 by14.5, and15.4by12.3millimeters (Harris).
Young.—The period of incubation is probably between 12 and 13 days, as with the Myrtle warbler. Mrs. Wheelock (1904) writes:
In the brood whose incubation was closely watched, I found that twelve days elapsed between the laying of the last egg and the advent of the young. The female did most of the brooding; the male was found on the nest only once, but was usually perched on a neighboring tree warbling his enthusiastic little song, “cheree-cheree-cheree-cheree.” After the young were feathered enough toleave the nest, which occurred when they were two weeks old, the male forgot to sing and became a veritable family drudge with the brood ever at his heels clamoring for food.* * *The pair whose young had hatched so early were very friendly, feeding them without much fear while I sat within three or four feet of the nest and on a level with it. They usually came with nothing to be seen in their beaks, but the insect food they had gleaned and carried in their own throats was regurgitated into the throats of the young. When the latter were five days old the mother bird, for the first time, brought an insect large enough to be seen, and crammed it into the open bill of one of the nestlings, and from that time on most of the food brought was eaten by the young while fresh.
The general opinion seems to be that two broods are often, perhaps usually, raised in a season. The young birds are the first to leave their mountain resorts, probably driven out by their parents, and are the first to appear in the lowlands.
Plumages.—The plumages and molts of Audubon’s warbler are similar in sequence to those of the myrtle warbler; in juvenal and first fall plumages the two species are almost indistinguishable, though there is always more white in the tail feathers of the western bird, in which the white spot usually reaches the fourth feather even in young birds. In any plumage the white areas in the tail of Audubon’s warbler occupy two more feathers on each side of the tail than in the myrtle warbler.
The juvenal Audubon’s warbler is brown above, streaked with black and white, and white below, streaked with black; the sexes are alike. This plumage is worn but a short time; Dr. Grinnell (1908) says that it “is of very short duration, not more than fifteen days, I should say”; and Swarth (1926) says that is “worn but a few weeks. Tail and wing have scarcely attained full length when the first winter plumage begins to appear, and by the time the birds are drifting back into the lowlands in September the last vestige of the juvenal plumage is gone.” This postjuvenal molt involves all the contour plumage and the wing coverts, but not the rest of the wings or the tail.
In the first winter plumage there is but slight difference between the sexes, the female being somewhat duller than the male and often with little or no yellow on the throat. In both sexes the plumage is browner throughout, the yellow areas are paler and less pronounced, the black streaks are less prominent, and the white areas in the tail are more restricted than in fall adults. Swarth continues: “All winter long these drab-colored birds pervade the lowlands, conspicuous only through force of numbers. Then, the latter part of March, comes the prenuptial molt that brings such marked changes to the male. This molt is extensive, far more so than with most of our birds in the spring, since it includes all of the plumage except flight-feathersand tail-feathers. At the close of the spring molt, about the middle of April as a rule, the male emerges, gorgeous in black breast and yellow trimmings, and with a showy white patch on either wing. The female, with similarly extensive molt, has changed but little in appearance.” He probably intended this as a description of the adult prenuptial molt, but that of the young bird is practically the same. However, the young bird in first nuptial plumage can always be recognized by the faded and worn primaries and tail feathers; otherwise, young and old are essentially alike. Adults have a complete postnuptial molt in August and a partial prenuptial molt, as outlined, in early spring. Mr. Swarth (1926) says: “In winter plumage, old and young, male and female, are all very similar, but there are minor differences by which the old male, at least, may be told from the others. The dark streaks on the sides of the breast are a little more pronounced, the yellow markings a little brighter, and the body color a little clearer gray, as compared with the browner young birds.”
Hybrids, or intergrades, occur occasionally between the different races ofauduboniandcoronatawhere their ranges approach or overlap.
Food.—Professor Beal (1907) examined the stomachs of 383 Audubon’s warblers taken in California from July to May, inclusive. The food consisted of 85 percent of animal matter (insects and spiders) and a little more than 15 percent of vegetable matter. The largest item was Hymenoptera, 26 percent, consisting mostly of ants, with some wasps, and a few parasitic species. Diptera accounted for 16 percent, including house flies, crane-flies, and gnats, many of which must have been caught on the wing, as this warbler is a good flycatcher. Bugs, Hemiptera, amounted to nearly 20 percent of the food, including the black olive scale, other scales, plant-lice, stink bugs, leaf-hoppers and tree-hoppers. “Plant lice (Aphididae) were contained in 39 stomachs, and from the number eaten appear to be favorite food. Several stomachs were entirely filled with them, and the stomachs in which they were found contained an average of 71 percent in each.” Caterpillars amounted to nearly 14 percent and beetles more than 6 percent of the food; most of the beetles were injurious species. Other insects and spiders made up about 2 percent.
The vegetable food consisted of fruits, mostly wild and of no value, less than 5 percent, and seeds, over 9 percent, mostly weed seeds and seeds of the poison oak. These warblers have been known to puncture grapes and they probably eat some late fruit, but they do very little damage to cultivated fruits and berries. C. S. Sharp (1903) observed a flock of 200 birds, mostly Audubon’s warblers, greedily eating the raisins in the tray shed of his packing house; they had to be constantly driven away. Mrs. Amelia S. Allen says in her notes that they collect in great flocks in the live oaks to feed on the oak worms in thespring, and that they eat myrica berries in the fall. John G. Tyler (1913) says: “Audubon warblers share with Say Phoebes the habit of catching flies from a window, sometimes becoming so engrossed in this occupation as to cling for several seconds to the screen where a south-facing window offers a bountiful supply of this kind of food.”
Behavior.—Audubon’s warbler is a lively and active bird that seems to be always in a hurry, constantly moving in pursuit of its prey. Mrs. Bailey (1902) writes:
Its flight and all its movements seem to be regulated by gnats, its days one continuous hunt for dinner. When insects are scarce it will fly hesitatingly through the air looking this way and that, its yellow rump spot always in evidence, but when it comes to an invisible gauzy-winged throng it zigzags through, snapping them up as it goes; then, perhaps, closing its wings it tumbles down to a bush, catches itself, and races pellmell after another insect that has caught its eye. In the parks it is especially fond of the palm tops frequented by the golden-crowned sparrows, and dashes around them in its mad helter-skelter fashion. The most straight-laced, conventional thing it ever does is to make flycatcher sallies from a post of observation when it has caught its insect. If it actually sits still a moment with wings hanging at its sides, its head is turning alertly, its bright eyes keen for action, and while you look it dashes away with a nervousquipinto midair, in hot pursuit of its prey.
It is not especially timid, being easy to approach when at its nest, and it shows its confidence in human nature by building its nest in trees in parks, over highways, in gardens, and even close to houses. Its behavior in the defense of its young shows a solicitude for their welfare. Jensen (1923) says: “If a nest with young is discovered, both parent birds try every means possible to draw the attention of the intruder away from the nest. Often I have seen them drop with folded wings from the top of a tree and flutter among the leaves as if each had a broken wing.” And Grinnell, Dixon, and Linsdale (1930) write:
June 15, 1925, a female Audubon warbler was seen which showed concern whenever the observer went near a certain thicket of very small pines and willows. The bird came to within three meters of the intruder and distracted his attention by going through an elaborate display. The bird spread its tail fan-wise, showing the white spots to greatest effect, and quivered the partly spread wings, toppling over backwards at the same time, as if unable to hold to the perch. For an instant the observer thought the bird’s foot was caught in the forking twigs. The inference finally made was that partly fledged young were in the low vegetation somewhere very near.
Voice.—Samuel F. Rathbun sends me the following note on the song of Audubon’s warbler: “The first note or two is given rather slowly, then its utterance is more rapid and with a somewhat rising inflection, the song closing a little hurriedly. It is quite a strong and sprightly song, but its charm lies mostly in the fact that it is one of the first, if not the very first, of the warbler songs heard in the spring. The call note given by both sexes is the same, a quick andslightly lisping one that is also used in the autumn and at times in flight.”
Dr. Walter P. Taylor (MS.) says of a song heard at Fort Valley, Ariz., on June 12, 1925: “The song seems much less full and seems lacking in quality, as compared with that of the Audubon in Washington State. It was so lacking in strength and quality that I took it for a Grace warbler.” He wrote it aswheetlea, wheetlea, repeated 7 or 8 times, orwheetoo, 7 times repeated, or againwheetleoo wheet, the final syllable a little different from the others.
Mrs. Bailey (1902) says: “His song is of a strong warbler type, opening toward the end,chwee, chwee-chwee-ah, chwee, between the song of the yellow warbler and that of the junco.” At Lake Burford, N. Mex., in May and June, according to Dr. Wetmore (1920), “males were found singing from the tops of the tallest pines and were slow and leisurely in their movements in great contrast to their habit at other seasons. Frequently while singing they remained on one perch for some time so that often it was difficult to find them. The song resembled the syllablestsil tsil tsil tsi tsi tsi tsi. In a way it was similar to that of the Myrtle Warbler but was louder and more decided in its character.”
Dr. Merrill (1888) says: “On two or three occasions I have heard a very sweet and peculiar song by the female, and only after shooting them in the act of singing could I convince myself of their identity.”
Field marks.—The male in his gay spring plumage is not likely to be confused with any other warbler except the myrtle warbler, from which it differs in having a brilliant yellow throat instead of a white one; in other words,audubonihas five patches of yellow against four forcoronata. In immature and fall plumages the two species are much alike, butaudubonihas four or five large white patches on each side of the tail, whilecoronatahas only two or three, in the different plumages; these white markings are diagnostic in any plumage. The yellow rump is always conspicuous at any season, even when the other yellow markings are more obscured.
Fall.—The fall migration is a reversal of the spring migration, from the north southward and from the mountains down to the valleys and lowlands. Rathbun tells me that the southward migrants pass through Washington during October and November, but that a few remain there and even farther north, in winter. In California, Audubon’s warblers that have bred in the mountains begin to drift downward to lower levels in August, the young birds coming first, so that by September they are well spread out over the lowlands almost down to sea-level. Soon after the first of October, the first of the migrants cross the border into Mexico on their way to winter quarters. Dr. Taylor tells me that in New Mexico during October these warblersare abundant in the aspens, being “by far the most numerous species of bird.”
Winter.—Audubon’s warbler is a hardy bird. At least some individuals remain in winter almost up to the northern limit of its breeding range; and while it retires entirely from its summer haunts in the mountains, most of its breeding range elsewhere is not wholly deserted. It probably remains as far north as it can make a living; its adaptability in finding a food supply helps in this and makes it one of the most successful of western birds as well as one of the most abundant in all parts of its range. A few remain, perhaps regularly, in coastal British Columbia, for Theed Pearse has given me five December dates and four February dates, spread out over a period of 10 years, on which he has recorded one or more Audubon’s warblers on Vancouver Island; on one of these dates, February 10, 1943, the temperature dropped to -6° F.
Rathbun tells me it is “of frequent, if not regular, occurrence during the winter” in Washington. And in Oregon Gabrielson and Jewett (1940) record it as a “permanent resident that has been noted in every county during summer and throughout western Oregon in winter.* * *Its little song is heard on every side during May and June, and its peculiarly distinct call or alarm note is a familiar sound throughout the balance of the year. This is true not only of the wooded slopes and bottoms but equally so of the weedy fence rows of the Willamette Valley, where during the short days of fall and winter these warblers may be found associating with the Golden-crowned Sparrows and Willow Goldfinches or sitting on the telephone wires with the Western Bluebirds.” Swarth (1926) writes:
In much of the West, especially in the Southwest, the Audubon’s warbler is one of the dominant species during the winter months. In southern California it vies with the Intermediate Sparrow and House Finch in point of numbers. Wherever there are birds at all, this bird is sure to be there. From the seacoast to the mountains, in city parks and gardens, in orchards and in chaparral, the Audubon’s warbler is equally at home. On any country walk scores are sure to be seen, starting up from the ground or out of the trees with wavering and erratic flight, showing in departure a flash of white-marked tail-feathers and a gleaming yellow rump spot, and uttering the incessantchipthat, better than any marking, serves to identify the fleeting bird.
In colder sections there are some fatalities; in the Fresno district, according to Tyler (1913), “a period of two or three unusually cold nights frequently results disastrously for these little warblers, and my observations show that there is a greater mortality among this species than in all other birds combined. After a hard freeze it is not an uncommon occurrence to see certain individuals that appear so benumbed as to be almost unable to fly, and not a few dead birds have been been found under trees along the streets.”
From much farther south, in Central America, Dr. Alexander F. Skutch (MS.) writes:
“Audubon’s warbler is a moderately abundant winter resident in the higher mountains of Guatemala, yet like the closely related myrtle warbler, appears to be less regular in its time of arrival and departure and less uniformly distributed, than the majority of the more common winter visitants. These attractive warblers were abundant on the Sierra de Tecpán from January until April, 1933; but strangely enough they did not return in August or September with all the other warblers that winter there; and none had appeared by the end of the year, although I kept close watch for them. Yet in the middle of the following September, I found them numerous among the pine and alder trees on the Sierra Cuchumatanes, nearly 11,000 feet above sea-level. The males were then resplendent in their full nuptial dress of yellow, black, white and gray, and sang enchantingly. I believe it not impossible that they breed in this remote, little-known region—for here also I found a breeding representative of the savannah sparrow, hitherto known only as a migrant in the country—and it is to be hoped that some day an ornithologist will study the bird-life of this lofty plateau during the breeding season, from April to August.
“During the winter months, the Audubon warblers are truly social, and are nearly always met in flocks, sometimes containing 25 or more individuals. They are versatile in their modes of finding food. Sometimes, from the tops of the tall cypress trees near the summit of the Sierra de Tecpán, they would launch themselves on long and skillfully executed sallies to snatch up insects on the wing. As they twisted about in the air, they would spread their tails to reveal the prettily contrasting areas of black and white. At other times they foraged on the ground, like the myrtle warblers; and this habit brought them into contact with the bluebirds (Sialia sialis guatemalae), which are likewise arboreal birds that frequently descend to hunt on the ground. At altitudes of 8,000 to 9,000 feet I almost always found the Audubon warblers and the bluebirds together in the bare, close-cropped pastures where there were scattered, low, oak trees; and this association was so constant that it could not have been accidental. Both kinds of birds were exceedingly wary as they hunted over the ground, and would fly up into the trees if they espied a man approaching them, even from a long way off. The Audubon warblers, probably because they more frequently enter open, exposed places, where they are conspicuous and far from shelter and must exercise great caution not to be surprised, were by far the shiest and most difficult to approach of all the warblers of the Sierra, whether resident or migratory. This was true whether they happened to be in the trees or on the ground.
“In the evening, foraging over the ground as they went, the Audubon warblers and bluebirds would go together to bathe in one of the rivulets that flowed through the pastures. After splashing vigorously in the shallow water they would fly up together into the raijón bushes, shake the drops from their feathers, sometimes wipe their wet faces against the branches, and put their plumage in order again. The last Audubon warbler that I saw in the spring was a lone female, who foraged in company with a pair of the resident bluebirds in the open pasture. She must have appreciated the companionship of the bluebirds more than ever, after all of her own kind had departed for more northerly regions.
“Guatemalan dates are: Sierra de Tecpán, January 16 to April 23, 1933; Sierra Cuchumatanes, September 13, 1934; Chichicastenango (Griscom), November 16.”
DISTRIBUTION
Range.—Western North America from central British Columbia to Guatemala.
Breeding range.—Audubon’s warbler breedsnorthto central British Columbia (Hazelton, Fort St. James, and Nukko Lake) and central western Alberta (Smoky River).Eastto southwestern Alberta (Smoky River, Jasper Park, Banff National Park, and Crowsnest Lake); casually to southwestern Saskatchewan (Cypress Hills); western Montana (Fortine, Teton County, Bozeman, and Fort Custer); western South Dakota (Harding County and the Black Hills); northwestern Nebraska (Warbonnet Canyon, Sioux County); central Colorado (Estes Park, Gold Hill, Colorado Springs, Wet Mountains, and Fort Garland); central New Mexico (Taos, Ruidoso, and Cloudcroft); western Texas (Guadalupe Mountains); and western Chihuahua (Pinos Altos); in migration much farther east.Southto central western Chihuahua (Pinos Altos); southeastern to north-central Arizona (Huachuca Mountains, Santa Catalina Mountains, Flagstaff, and Grand Canyon); southwestern Utah (Zion National Park); southern Nevada (Charleston Mountains); central southern California (San Bernardino Mountains and the Santa Rosa Mountains); and northern Baja California (Sierra San Pedro Mártir).Westto northern Baja California (Sierra San Pedro Mártir); southwestern California (San Jacinto Mountains and Mount Wilson); central eastern California (Yosemite Valley and Big Trees); western California (Diablo, Mount Tamalpais, Fort Ross, and Trinity Mountains); western Oregon (Coos Bay, Eugene, Corvallis, and Netarts); western Washington (Cape Disappointment, Shelton, and the San Juan Islands); and western British Columbia (Cowichan Lake and Port Hardy, Vancouver Island; and Hazelton).
Winter range.—The Audubon warbler is found in winternorthto southwestern British Columbia (Comox and Chilliwack).Eastto southwestern British Columbia (Chilliwack); central Washington (Yakima); occasionally eastern Washington (Cheney); northeastern Oregon, casually (Pendleton and Legrande); central California (Marysville and Fresno); casually to southwestern Utah (St. George and Zion National Park); central Arizona (Fort Mojave, Fort Verde, Salt River National Wildlife Refuge, and Tombstone); southern Texas (El Paso, rarely Knickerbocker, and Brownsville); Tamaulipas (Matamoros and Victoria); western Veracruz (Orizaba); and central Guatemala (San Jerónimo).Southto Guatemala (San Jerónimo, Tecpán, and San Lucas); casual or accidental south to central Costa Rica (Juan Viñas).Westto western Guatemala (San Lucas and Totonicapán); Oaxaca (Parada); Guerrero (Chilpancingo and Coyuca); western Jalisco (Tonila); Nayarit (Tepic); southern Sinaloa (Mazatlán); western Baja California (Santa Margarita and Natividad Islands); and the west coast of the United States to southwestern British Columbia (Comox).
The preceding range is for the species as a whole of which two subspecies or geographic races are recognized. The Pacific Audubon’s warbler (D. a. auduboni) breeds south to southern California, central Arizona, and New Mexico; the black-fronted Audubon’s warbler (D. a. nigrifrons) breeds from the Huachuca Mountains, Ariz., through the mountains to southwestern Chihuahua.
Migration.—Late dates of spring departure from the winter range are: Guatemala—Tecpán, April 23. Sonora—Moctezuma, May 23. Texas—Marathon, May 18. Kansas—Fort Wallace, May 27. Arizona—Prescott, May 19. California—Fresno, May 3.
Early dates of spring arrival are: Kansas—Garden City, April 22. Nebraska—Hastings, April 14. New Mexico—Apache, March 7. Colorado—Colorado Springs, April 12. Wyoming—Laramie, April 21. Montana—Fortine, April 14. Alberta—Banff, April 23. Utah—St. George, March 8. Nevada—Carson City, April 10. Idaho—Sandpoint, April 16. California—Grass Valley, April 10. Oregon—Prospect, March 6. Washington—Shelton, March 4. British Columbia—Summerland, March 30.
Late dates of fall departure are: British Columbia—Okanagan Landing, October 24. Washington—Pullman, November 13. Oregon—Prospect, November 18. Idaho—Bayview, October 26. Utah—St. George, December 7. Alberta—Edmonton, September 11. Montana—Fortine, October 24. Wyoming—Laramie, November 9. Colorado—Fort Morgan, October 30. New Mexico—Silver City, November 10.