Yellow-rumped Warbler

Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.

Bent Life History for the Yellow-rumped Warbler – the common name and sub-species reflect the nomenclature in use at the time the description was written.

We used to call this the yellow-rumped warbler, a none too distinctive name, as other warblers have yellow rumps. Another early and slightly better name, “yellow-crowned wood warbler,” reflected the scientific name coionata and was based on the old Edwards name “golden-crowned fly-catcher.” The present name, Eastern myrtle warbler, comes from its fondness for the berries of the waxmyrtle (Myrica cerifera); and in the south, where it is conunon in winter, it is often called the myrtlebird.

Next to the yellow warbler, this is probably the best known of the wood warblers and is about the second one of the group that the novice learns to recognize. All through the eastern United States this is by far the most abundant warbler on both migrations, being about the first to arrive in the spring and the last to leave in the fall, often remaining all winter nearly up to the southern limits of its breeding range. It is a large, conspicuous warbler, not at all shy, and is to be found almost anywhere, often in enormous numbers. The breeding range of the species is one of the most extensive, extending from the tree limit in Alaska and northern Canada down through the coniferous forests into the northern tier of States, and even farther south in the mountains. Its winter range is still more extensive. It spends the winter farther north than any other wood warbler, although more or less sparingly and irregularly in the northern States, and its range extends through the Bahamas, the northern West Indies, Mexico, and Central America to Panama. There is no wonder that it is well known. But neither Wilson, Audubon, nor Nuttall ever found its nest.

Spring: Professor Cooke (1904) writes:

The myrtle warbler is one of the first migrants to move northward. A large flight struck the Alligator Reef lighthouse February 23, 1892, and some 00 birds struck the Sombrero Key lighthouse March 3, 1889. By the middle of March migration Is well under way over all the winter range, and the foremost birds keep close behind the disappearance of frost. * * * By the last of March all the myrtle warblers have departed from Jamaica, Haiti, Cuba, and the Bahamas. The latest recorded date of striking of this species at any of the Florida lighthouses is April 3, 1889. By the middle of the month the latest northbound birds have left southern Florida. * S * Most of the migrants cross the Rio Grande into Texas about the middle of March, and it Is the middle of April before the last have passed north.

Charles L. Whittle (1922) witnessed a heavy migration of myrtle warbiers along the coastal islands of South Carolina on March 4, 1920, that seemed to have been influenced largely by the presence of the waxmyrtle (Mydca cerifera). He says:

Perhaps half a mile from the northeast end of Sullivan Island the belt of waxmyrtle trees narrows to a width, measured northwest and southeast, of about three hundred feet. Here, near a seashore resort, a road had been recently cut across the belt of waxmyrtle trees at right angles to the snnd bar. Streams of warblers flying along the shore northeasterly from Folly and Morris Islands, just south of the entrance to Charleston harbor, dropped to the land and converged at the southwest end of the mantle of myrtle trees and passed across the open swath cut for the new road.. Posting ourselves here we counted the birds moving northeast, minute by minute as they passed the opening, for half an hour. The flight was continuous, many of the birds lighting on the ground and trees from time to time, aiid the number crossing per minute varied from twenty to two hundred, and accordingly averaged about one hundred per minute. As far as we could judge the numher was no greater than it had been all the time since our arrival at the shore. Taking, therefore, the average at one hundred per mInute, 24,000 Myrtle Warbiers passed northward between nine in the morning and one in the afternoon. Not only so, but additional warbiers passed close by both to the east and to the west of the stream of birds nader observation. No doubt also the migration began prior to nine in the morning and did not cease at one In the afternoon.

He points out that the northern species of myrtle, or bayberry (Myrica pensylvanica), extends all along the coast from Ne~ Brunswick and Nova Scotia to Florida; and he suggests that if these warblers prefer to migrate a long a coastal route where these myrtles reach their maximum development and where the climate may be milder than at higher elevations inland, it may explain why they generally arrive in New Brunswick a week earlier than in Pennsylvania. Milton P. Skinner (1928) says that, in the North Carolina sandhills, “early in March the movement becomes conspicuous, and great numbers of these warbiers are then seen constantly moving through the forests and across the fields in steady streams, flitting about a few minutes, and then passing on to the northeast. These movements are near the ground, or among the tree trunks, but at other times the birds are above the tallest trees. The general direction is from the southwest to the northeast, with fifty to a hundred warbiers passing over a field each hour of every day for at least two weeks.”

At Buckeye Lake, Ohio, according to Milton B. Trautman (1940): No warbler species migrated through the area In such consistently large numbers as did the Myrtle Warbler, and none bad a more prolonged spring or fall migration. The first spring transients, mostly brilliant colored males, were generally seen between April 12 and 20. Thereafter the number of individuals increased rapidly, and from May 1 to May 5 between 100 and 200 birds, mostly males, could generally be daily noted. A marked decrease usually followed this migration wave. Between May 10 and 18, during the period of maximum numbers for most warbler species, there was a second large wave and then 150 to 500, mostly females and young males, were observed daily. A drastic decline in numbers took place shortly after May 18, and by May 23 few or none remained.

The migration is about the same in Massachusetts. The birds come in waves, the adult males preceding the females. We usually see the first arrivals about the middle of April, drifting through the leafless treetops in the tall deciduous woods where we look for hawks’ nests; in their brilliant new plumage with gleaming yellow patches they are easily recognized as myrtle warblers, even in the tops of the 60-foot trees. Mr. Forbush (1929) gives this picture of the later waves:

In the latter days of April or very early in May when the south wind blows. when houstonias and violets begin to bloom on sunny southern slopes, when the wild cherry and apples trees and some of the birches, sumacs and the shrubbery in sheltered sunny nooks begin to put out a misty greenery of tiny leaflets, then we may look for the Myrtle Warblers, the males lovely In their nuptial dress of blue-gray, black, white and lemon-yellow. Then they may be found fluttering about in sheltered bushy hogs, catching the early Insects that dance In the sunshine along the water-side. All through early May they move northward, or westward toward the mountains, migrating by day or night indifferently as the case may be.

Soon most of them have passed beyond our borders and reached their summer homes in the coniferous forests of the Canadian Zone, the first of the family to come, close on the heels of retreating winter and while frost and snow still linger in the northern woods.

Courtship: The courtship of the myrtle warbler must be a very pretty performance. Two brief accounts of it have been published: “As summer approaches the males begin their courtship of the females, following them about and displaying their beauties by fluffing out the feathers of their sides, raising their wings and erecting the feathers of the crown, so as to exhibit to the full their beautiful black and yellow markings. After much time spent in courting they mate, and at once look about for a nesting place” (Forbush, 1929). Males seeking mates “made advances to the female contingency, hopping from twig to twig with outspread wings, chipping and fluttering, now repulsed by the fair one, and now accepted by another one to whom advances were made, to finally spend a few days in a favorable spot and begin nest building” (Knight, 1908).

Nesting: On August 1,1907, at Clarkes Harbor, Nova Scotia, I found the first and only nest of the myrtle warbler that I have ever seen; it was about 15 feet from the ground on a horizontal branch of a large spruce tree, about 5 feet out from the trunk, and contained three young birds that were nearly fully feathered. Robie W. Tufts says in his Nova Scotia notes: “I have seen these nests built at varying heights from 5 to 50 feet high. One found on June 6, 1919, contained four slightly incubated eggs. It was placed close to the stem of a pine tree, near the top, about 50 feet up. My field experiences tend to support the theory that these birds normally raise two broods a year.” He found one nest built in an apple tree in an orchard, of which he says: “Of the large number of nests of this species I have examined, this is the only one not built in a conifer.”

There are two Nova Scotia nests of the myrtle warbler in the Thayer collection in Cambridge, both taken by H. F. Tufts. They are slightly different in composition and structure, but are probably fairly typical of the species. One, found saddled on a spruce limb 10 feet from the ground, is rather bulky and loosely built; the foundation and sides are made of fine coniferous twigs mixed on the bottom with grasses and rootlets and around the rim firmly interwoven with black horsehair, or perhaps moose hair, and finer rootlets; the cup is smoothly lined with finer hair and feathers. Externally it measures, roughly, 4 by 5 inches in diameter and about 2 inches in height; the cup is about 2 inches in diameter and 13,4 inches deep. The other, a very pretty nest found 8 feet up in a small spruce, close to the trunk, is more firmly and compactly built; the base and sides are made up mainly of green mosses and a few gray lichens mixed with fine twigs and a few fine grasses, all firmly interwoven; internally the cup is smoothly lined with fine black and white hairs on top of a few feathers. Externally it measures 21/4 inches in height and 3 by ~½ inches in diameter; the cup is 2 inches in diameter and about 11/2 inches deep.

Of nestings in Maine, Knight (1908) says: “As soon as nest building begins, the favorite locality selected is a thicket of evergreen trees near the highway, some open pasture containing a few clumps of scattered evergreens, small thickets of evergreens along the banks of some stream or river or about the shore of a pond or lake, or a row of trees about some country dwelling or in an orchard. In the vast majority of cases an evergreen tree is selected as a nesting site, though occasionally some hardwood tree, such as maple, apple or birch, may be taken. A majority of nests seem to be placed in cedar trees, with fir and spruce following as close second choices.”

Forbush (1929) mentions two Massachusetts nests in tall white pines. A nest studied by Mrs. Nice (1930a), at Pelham, Mass., was “six feet up in a small red cedar on a branch next to the trunk. It was a rather shallow affair, composed of cedar twigs and bark, plant fibers, a piece of string and pine needles, and was lined with a few horse hairs and many Ruffed Grouse feathers.”

Dr. Paul Harrington has sent me his notes based on the study of 44 nests of the myrtle warbler in Simcoe County, Ontario. He says that the white pine is generally chosen as a nesting tree, the nests being placed from 6 to 40 feet up, averaging 15 feet; “28 nests were built on horizontal limbs about two-thirds out from the trunk, but none at the outermost end. They were conspicuous from below but not from above, as clumps of needles overhung them in such a way as to afford good protection.” Of the remainder, 2 were built in the top clump of needles in young trees; 5 were in small spruces, the lowest 3 feet, the highest 15, and all on horizontal limbs, 3 near the trunk and 2 halfway out on the limb; 5 were about 15 feet up in crotches of small cedars; 3 were found in red pines, in the outermost clumps of needles 10 to 15 feet from the ground; and 1 nest was 6 feet up in a small balsam. He says that the nest is lined thickly with feathers and a few hairs. “The feathers are so placed that, as well as lining the nest, they form a screen over the inside when the bird is not sitting. This is done by the shafts of the feathers being woven or imbedded into the inside of the nest and the vane lying free.” At Petawa he found these birds nesting in small jack pines.

Dr. F. A. E. Starr, in his notes from northern Ontario, also says that any conifers are suitable nesting sites: “I have found only one exception to the use of a conifer. This .nest was built in a hawthorn, and when I collected the nest, the birds moved to a cedar.” A. D. Henderson writes to me: “The myrtle warbler is a fairly numerous summer resident at Belvedere, Alberta, and in the Fort Assiniboine District. It nests mainly in the muskegs in tamarack and spruce trees, but occasionally in deciduous trees close to a muskeg.” The nests are mostly from 10 to 15 feet up. One nest was in a jack pine, “in a bunchy growth at the end of a limb.” Baird, Brewer, and Ridgway (1874) state that MacFarlane found nests on the ground in the Anderson River region.

Eggs: Most observers agree that four or five eggs form the usual set for the myrtle warbler. Tufts (MS.) says that “five eggs are more commonly found than four.” Dr. Starr says in his notes that “four eggs are rarely laid, two and three being the usual numbers, while sometimes only one is laid, along with those of the cowbird.” This is probably an abnormal situation in which the cowbird fills the nest with its own eggs, leaving little room for those of the warbler.

The eggs are ovate to short ovate and slightly glossy. The ground color is creamy white and is speckled, spotted, or blotched with “auburn,” “argus brown,” “Brussels brown,” “chestnut brown,” or “cinnamon-brown,” with undermarks of “light brownish drab,’~~~vinaceous gray,” or “purplish gray.” Generally the spots are concentrated at the large end, forming a wreath, but some are marked all over and may also have a few scrawls of blackish brown. I think the handsomest are those having the rich creamy white ground almost immaculate except for a solid wreath, around the large end, of spots and blotches of the browns overlapping and intermingled with the undertones of gray, so that they resemble somewhat the eggs of the wood pewee. On lightly marked eggs the drab or gray spots are the most prominent. The measurements of 50 eggs average 17.5 by 13.3 millimeters; the eggs showing the four extremes measure 20.3 by 13.2, 17.9 by 14.8, 14.8 by 12.9, and 16.0 by 12.4 millimeters (Harris).

Young: The incubation period for the myrtle warbler is from 12 to 13 days and the young remain in the nest normally from 12 to 14 days. Incubating the eggs and brooding the young is apparently done entirely by the female, but both parents are active in feeding the young and in cleaning the nest. Mrs. Nice (1930a), with the help of Miss Lucille Baker, watched a nest containing young for a total of 19 hours, over a period of 6 days. On the first day the female brooded 25 percent of the time, but less later on; the brooding periods averaged 9 minutes.

A great deal of her energy was expended in delousing the nest: thirty-six minutes on July 28 and seventy-four minutes during the forenoon of the next day, but after that there was little trouble. Once, during thirteen minutes she made over 250 captures, all of which she ate. * * *

The male brought food sixty times, the female forty-eight times, so that the young were fed once in 10.9 minutes. About one-third of the time the male brought two insects, while the female did so on about one-sixth of her trips. During the fourteen hours of observation, the male brought food once in every nineteen minutes, the female once in every twenty-eight minutes. During the last five and one-half hours, the male brought food once In twenty-two minutes, the female once in eIghteen minutes. * * *

Excreta were eaten by the female through July 29, but she carried one away at 7: 05 P. M., July 28. She ate twelve sacs and carried eleven; her mate carried twenty-five and ate one. * * * He picked ilce off his legs and gave them to the babies.

Mr. Knight (1908) says: “The female does most of the work of incubation, but on very rare and exceptional occasions I have found the male bird incubating and even engaged in song while on the nest. * * * The natal down rapidly dries and fluffs out on the young birds and is sepia-brown in color. At the end of six to seven days pin feathers begin to appear, and by the twelfth to fourteenth day the young are well advanced in their juvenal plumage and able to scramble out of the nest. Two to three days after leaving the nest they are able to essay short flights.”

Plumages: Mr. Knight (1908) refers to the natal down as sepiabrown. Dr. Dwight (1900) describes the juvenal plumage, in which the sexes are alike, as “above, the feathers centrally dull black, edged with drab and buffy brown, producing a streaked effect. Below, much whiter but similarly streaked, a tinge of pale primrose-yellow on the abdomen. Wings and tail dull black, edged with drab, palest on primaries and outer rectrices. Two very indistinct buffy white wing bands. Upper and lower eyelids with dull white spots.”

The first winter plumage is acquired by a partial postjuvenal molt in August, which involves the contour plumage and the wing coverts, but not the rest of the wings or the tail. This plumage is entirely different from the juvenal and the sexes are only slightly differentiated. Dr. Dwight (1900) describes the young male as “above, sepia-brown, grayer on the back and obscurely streaked with black, the rump and a concealed crown spot lemon-yellow, the upper tail coverts black, broadly edged with plumbeous gray. Wing coverts black, plumbeous edged and tipped with white tinged with wood-brown forming two wing bands. Below, dull white, washed with pale buff on the throat and sides and obscurely streaked on the breast and sides with black, veiled by whitish edgings. Sides of breast with dull yellow patches. Incomplete orbital ring and faintly indicated superciliary stripe white or buffy.” He says of the young female: “The black streaking of this dress is less obvious both above and below than in the male, the plumage everywhere is browner, and the crown patch very obscure.”

The extensive prenuptial molt begins early, usually in March, before the birds have left their winter quarters; a few new feathers may be assumed even in late February but most of the molt occurs in April while the birds are migrating; it is, however, generally completed by the time the birds have reached their breeding grounds. Dr. Dwight (1900) says this molt “involves most of the body plumage and wing coverts, occasionally a tertiary but not the rest of the wings nor the tail. The black and gray of the upper surface, the white wing bars and the yellow crown and rump are new, some of the old upper tail coverts and a part of the feathers of the abdomen and crissum being retained in many cases, those of the back and elsewhere less often. Young and old become practically indistinguishable although the young usually have browner and more worn wings and tails, obvious in the primary coverts, but the differences are not absolute.” In the female, “the first nuptial plumage is assumed by a restricted moult, leaving behind many brown feathers. The brown feathers of the bros and auriculars are assumed by moult.”

The adult winter plumage is acquired by a complete postnuptial molt, beginning late in July. In the male, this “differs little from the first winter dress, but the wings and tail are blacker with brighter gray edgings, noticeable especially in the primary coverts. The back is usually grayer and the lower parts whiter, with broader streakings above and below.” In the female there are similar differences, the adult winter female resembling the young male at that season. Adults have a complete postnuptial molt in July and a prenuptial molt as in the young birds.

Food: Forbush (1929) sums up the food of this warbler very well as follows:

The Myrtle Warbler is one of the few warhiers that can subsist for long periods upon berries and seeds, although undoubtedly it prefers Insects when it can get them. Along the coast during the milder winters there are many flies rising from the seaweed in sheltered spots on mild days even in January, and there are eggs of plant-lice and some hibernating Insects to be found on the trees, but the principal food of the Myrtle Warbler in New England during the inclement season is the bayberry. They can exist, however, on the berries of the Virginia juniper or red cedar and these seem to form their principal food when wintering in the interior; berries of the Virginia creeper or woodbine, those of viburnums, honeysuckle, mountain ash, poison Ivy, spikenard and dogwoods also serve to eke out the birds’ bill of fare. In the maple sugar orchards In early spring they occasionally drink sweet sap from the trees. In the southern Atlantic states they take palmetto berries. North and south they also eat some seeds, particularly those of sunflower and goldenrod. During spring and summer they destroy thousands of caterpillars, small grubs and the larvae of saw-flies and various insects, leaf-beetles, dark-beetles, weevils, wood-horers, ants, scale insects, plant-lice and their eggs, Including the woolly apple-tree aphis and the the common app~e-1eaf plant-louse, also grasshoppers and locusts, bugs, house-flies and other flies including caddice-flies, craneflies, calcid-flies, ichneumon-flies and gnats, also spiders.

To the above comprehensive list there is little to be added, although wild cranberries and the berries of the poison sumac might have been included. Myrtle warblers are doubtless instrumental in spreading the seeds of poisonous species of Rhu&, which is not to their credit; they also help to disseminate the red cedar, as they digest only the outer covering of these three and the bayberries. These warblers are often seen on the beaches and sand dunes eating the seeds of the beachgrass, or in open fields feeding on grass seed and doubtless various weed seeds. They frequent the fresh holes bored by sapsuckers to drink the flowing sap and eat the insects that are attracted to it. In Florida, in winter, they drink the juice of fallen oranges in the groves and even the broken oranges on the trees.

They are somewhat expert as flycatchers, taking mosquitos and gnats in the air. Knight (1908) writes: “During the fall months they enter the city gardens and orchards, climb over the roofs and along the gutters of houses, peering into every nook and cranny. They hover on beating wings about such crannies of the clapboards and finish where they may have spied some delicious, big fat spider, chrysalis or other delectable morsel, and such finds are speedily devoured. Now peering, now hovering, and now springing into the air after some winged insect, they stop about a building for a few hours or days, slowly but surely retreating southward.”

Behavior: Much of the behavior of this friendly little bird has been referred to in connection with its activities about our homes and gardens and its nesting habits. Tilford Moore tells me that “these birds seem to have a tendency toward ‘creeperism,’ in that they are often seen hanging to the bark of a vertical trunk or branch, and are usually on the larger branches rather than among the smaller twigs. Th~y often flutter a lot when hanging to the bark.” And Wendell Taber sends me this note: “On May 5, 1940, Richard Stackpole and I watched a flock in West Newbury, Mass. The birds were running about on the grass near a stream. Again, they would alight at the base of a tree and run up it several feet. I think all the birds that performed this feat were females. They were most deceptive, and we kept thinking we were seeing brown creepers until we put field glasses on them.”

William Brewster (1938) writes of the behavior of a female about her nest, 35 feet from the ground in a hemlock: “The female Yellowrump was sitting and for some time she absolutely refused to leave her eggs. Watrous first shook the branch and then with a long stick poked and shook smartly the twigs within an inch or two of her head. At length she hopped out of the nest and stood for a moment or more on its rim looking about her. Then she fluttered down towards the ground with quivering wings and wide spread tail, moving slowly and alighting several times on a branch or cluster of twigs where she would lie prostrate for a moment beating her wings feebly and simulating the movements of a wounded or otherwise disabled bird.”

Dr. Stone (1937) describes the flight of the myrtle warbler very well:

We soon learn to identify their rather jerky flight as they rise from the hushes, and with a series of short wing flips turn now to the right, now to the left, In their zigzag progress, rising so~~~~xvhat with the beats, and falling in the intervals. Sometinies a bird will go hut a short distance, flitting from hush to bush, while others will climb higher and higher in the air, drifting in their jerky way across the sky like wind-hiown leaves. * * *

As soon as a Myrtlebird alights on a hush there is a short, sharp flip of the tail, not a seesaw action, hut one involving the hody as well, and as it comes to rest the head is drawn in and the plumage ruShed 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, 1041, 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,~ seconds 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, tohicle, is louder than in most warblers. I found it pitched on D”. Another note is a fainter tseet 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 sang whee whee whee whee whee whee whee whee hew hew, sometimes with three or even four hew& at 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 ehing ching ching weedle weedle ‘weet.

“The ordinary call-note is a hoarse ehep, easily distinguished from the call of any other New England warbler. I have also heard occasionally a slight teip or tsit, suggesting a. chickadee. The feeding call of the young out of the nest is a rapid succession of several explosive chip8 or p~t8 with 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 as wheedle 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 is much 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 September or 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 hrushy 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 coimnonly or rarely and irregularly farther north. It is the only one of the wood warbler that is hardy enough to brave the rigors of our northern winters amid ice and snow and sometir~ies zero temperatures.

Robert Ridgway (1889) writing of its winter habits in southern Illinois, says:

It may often be seen In midwinter, when the ground is covered with snow, in the door-yards along with Snowbirds (Jutwo hyemaUa), 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 boles in the straw- or hay-stacks, in the barn-yard. A favorite food of this species are the berries of the Poisonvine (Rhus tosicodendron), and during the early part of winter large numbers of them may be seen wherever vines of this species are abundant.

What few myrtle warbiers 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 warbiers 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 twentyfourth, 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, whereï 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, wheeling and dropping together, moving always as though actuated by a true group spirit. During three days on thatplantation, 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 waterthrushes, 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 T~rraba 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 warbiers associating intimately with the flycatchers; just as, in the Guatemalan highlands, I had found Audubon’s warbiers flocking with bluebirds. The myrtle warbiers 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 warbiers 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 Tecp~n, March 16, 1933; Finca Mocft, 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 Zeled6n), March 18; Carrillo (Underwood), October 2; Guacimo (Carriker), December 4; Las Cafias, 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 breeds north to northern Alaska (Kobuk River and timberline on the south slope of the Brooks Range) ; northern Yukon (La Pierre House) ; northern Mackenzie (Akiavik; 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 IRigolet, possibly Nain and Okkak). East to 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). South to 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 Peiham) ; 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). West to western Alaska (Nushagak, Russian Mission, St. Michael, and the Kohuk River). Winter range: The myrtle warbler winters in two discontinuous areas. The principal winter home is north to 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 irregularly north to Holly, Cob.; Hays and Manhattan, Kan.; Madison, Wis.; Chicago, Ill.; Battle Creek and Rochester (one banded in January), Mich.; Rochester, N. Y.; and Portland, Maine. East to 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 Sanchez) ; Puerto Rico (San Juan) ; St. Croix Island; and rarely, Antigua. South to Antigus, northern Colombia, rare or accidental (Santa Marta region) ; and Panam6, (Pearl Islands). West to Panam~ (Pearl Islands, Canal Zone, and Almirante); Costa Rica (El General and Guayabo); eastern Nicaragua (Greytown and the Rio Escondido); northern Honduras (Puerto Castilla and Lancetilla); western Guatemala (Duefias and TecpAn) ; eastern Oaxaca (Tehuantepec); Veracruz (Orizaba); Tamaulipas (Victoria); Nuevo Le6n (Monterrey) ; southwestern Texas (mouth of the Pecos River, Camp Barkeley, Taylor County, and Fort Worth); and central Oklahoma (Oklahoma City). The western winter range is north to central Western Oregon (Newport and Albany). East to western Oregon (Albany) ; central California (Marysville, Stockton, Mariposa County, Redlands, and Potholes); southern Arizona (Tucson and Tombstone); and southwestern Sonora (Guaymas). South to southern Sonora. West to 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. e. ho&veri) breeds from western Alaska and northwestern Mackenzie to central Alberta and central British Columbia; the eastern myrtle warbler (D. c. coroiu~ta) from western Saskatchewan eastward. Migration: Late dates of spring departure from the winter home are: Costa Rica: Guayabo, March 18. El Salvador: Volc~n de San Miguel, March 22. Guatemala: Nebaj, April 27. Honduras: Lancetilla, March 17. Mexico: Valles, San Luis Potosi, May 2. Puerto Rico: Mayagiiez, 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. lowa: 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. lowa: 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, Novem her 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, November19. 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. lowa: 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: Mayagiiez, 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 61/2 years 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 670 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).

ALASKA MYRTLE WARBLER
DENDROICA CORONATA HOOVERI McGregor
HABITS

The Alaska myrtle warbler is another subspecies that was described many years ago but only recently admitted to the A. 0. 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 it Dendroica coronata hooveri, hoover’s warbler. In his description of it he says that it is “in colors and markings like Dendroica co’ronata, 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 than 1/o inch! 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 black breast 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 Warbiers 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 of trepeated ‘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 Warbiers 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 warbiers, mostly this species, flitted rapidly through the poplar woods, and there was a constant stream of myrtle warbiers 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 of coro~nata and auduboni. 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 is D. o. hoaveri.”

PACIFIC AUDUBON’S WARBLER
DENDROICA AUDUBONI AUDUBONI (Townsend)
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 t.he pines, firs, and spruces. Including the range of the Rocky Mountain form (menwrabili.s), which has not yet been admitted to the A. 0. U. Check-List, the type race breeds from central British Columbia, central Alberta, and west-central Saskatehewan 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 breedingseason.

In the mountains of New Mexico it has been found breeding at altitudes of form 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 warbiers 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 lodge. pole pines and other conifers of the Canadian and Hudsonlan 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. Woodhury (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 ~ip 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, a.nd 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 warbiers 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 ever 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 Warbiers 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. nigrifron,s) 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 secondï ‘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, bringing D. aestiva morcomi and II. lutescen,s with 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, found May 2, 1909, on the east side of Lake Washington and along a road, was 80 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 2% in depth; and inside 2 by 1½ inches. 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, Cob., 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 2Y~ x 13A, and 1Y2 inches deep.” Dr. Chapman (1907) describes a nest from Estee Park, Cob., 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.” lIe 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 Saii 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 lodgpole 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 measure 19.4 by 14.0,19.1 by 14.5, and 15.4 by 12.3 millimeters (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 to leave 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 bad batched so early were very friendly, feeding them without mucb 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 nestllngs, 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 j uvenal 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 plulnage 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-feathers and 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 of auduboni and coronata where 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 the spring, and that they eat myrica berries in the fall. John G. Tyler (1913) says: “Audubon warbiers 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 pelimell 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 nervous quji, Into 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 and slightly 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 as wheetlea, wheetlea, repeated 7 or 8 times, or wheetoo, 7 times repeated, or again wheetleoo 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, ehwee, between the song of the yellow warbler and that of the jun00.” 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 syllables tsil tsil t8il t8i 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, audubo’ni has five patches of yellow against four for coronata. In immature and fall plumages the two species are much alike, but ctuduboni has four or five large white patches on each side of the tail, while coronata has 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 warbiers are 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 warbiers 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, tile 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 incessant chip that, 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 Tecpiin 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 sealevel. 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 Tecp~n, 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 sia~is 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 warbiers 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 raij6n 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 Tecp~n, 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 breeds north to central British Columbia (Hazelton, Fort St. James, and Nukko Lake) and central western Alberta (Smoky River). East to southwestern Alberta (Smoky River, Jasper Park, Banif 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 (Pubs Altos) ; in migration much farther east. South to central western Chihuahua (Pinos Altos); southeastern to northcentral Arizona (Iluachuca 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 M~rtir). West to northern Baja California (Sierra San Pedro M~rtir) ; 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 winter north to southwestern British Columbia (Comox and Chulliwack). East to southwestern British Columbia (Chilliwack) ; central XVashington (Yakirna) ; 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 Moj aye, 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 Jer6nimo). South to Guatemala (San Jer6nimo, Tecp~in, and San Lucas); casual or accidental south to central Costa Rica (Juan Vifias). West to western Guatemala (San Lucas and Totonicap~n); Gaxaca (Parada); Guerrero (Chilpancingo and Coyuca); western Jalisco (Tonila); Nayarit (Tepic); southern Sinaba (Mazatl6n); westerA 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 (~. 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 Moutains, Ariz., through the mountains to southwestern Chihuahua.

Migration: Late dates of spring departure from the winter range are: Guatemala: Tecp~in, 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: Banif, 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.

Early dates of fall arrival are: California: San Diego, September 2. Texas: Fort Davis, September 9. Sonora: Las Cuevas, September 3. Guatemala: Chichicastenango, November 16.

Banding: An Audubon’s warbler that was banded at Santa Cruz, Calif., on February 17, 1931, was found dead November 5, 1931, at Glenwood, Calif. Another, banded at Altadena, Calif., on December 1, 1935, was retrapped at the same station on February 13, 1940, being then nearly 5 years old, at the least.

Casual records: A specimen of Audubon’s warbler was collected at Cambridge, Mass., on November 15, 1876. Another was collected at West Chester, Pa., November 8, 1889. In Ohio one was closely watched at Cleveland April 30 and May 3, 1931; and a second one at Richmond on October 5, 1941. On April 28, 1928, one was closely watched at Minneapolis, Minn.

Egg dates: California: 53 records, May 11 to July 30; 28 records, June 13 to 25, indicating the height of the season. Colorado: 10 records, June 18 to July 6; 5 records, June 19 to 29.

Washington: 11 records, April 19 to June 29; 5 records, May 14 to June 13.

BLACK-FRONTED AUDUBON’S WARBLER
DENDROICA AUDUBONI NIGRIFRONS (Brewster)
HABITS

The black-fronted Audubon’s warbler was originally described by William Brewster (1889) as a distinct species, based on a series of five specimens collected by M. A. Frazar in the Sierra Madre Mountains of Chihuahua, Mexico, in June and July, 1888. He gave as its characters: “Male similar to D. auduloni but with the forehead and sides of the crown and head nearly uniform black, the interscapulars so closely spotted that the black of their centres exceeds in extent the bluish ashy on their edges and tips, the black of the breast patch wholly unmixed with lighter color. Female with the general coloring, especially on the head, darker than in female auduboni; the dark markings of the breast and back coarser and more numerous; the entire pileum, including the yellow crown patch, spotted finely but thickly with slaty black.” He admits that it is closely related to D. auduho’ni, “so closely in fact that the two may prove to intergrade,” but he found no indications of such intergradation. Later, however, Leverett M. ïLoomis (1901) called attention to the fact that several birds, collected in the Huachuca and Chiricahua Mountains, in Arizona, showed signs of intergradation with breeding birds from central California. These were taken by W. W. Price, establishing this bird as an addition to our fauna, and resulting in its reduction to subspecific rank. It is known to breed in the Huachuca Mountains and in the high Sierras of northwestern Mexico, ranging south to Guatemala. Swartli (1904) says of the status of the black-fronted warbler in Arizona:

This, the only form of auduboni that breeds in the Huachucas, occurs during the summer months, though in rather limited numbers, in the higher pine regions from S500 feet upwards. On one occasion, April 5, 1903, I secured a male nigrifrons from a flock of audubowi feeding In some live-oaks near the mouth of one of the canyons at an altitude of about 4500 feet, but this is the only time that I have seen it below the altitude given above; and it is also exceptional in the early date of Its arrival. No more were seen until the second week in May, which seems nearer the usual time of arrival, for in 1902, the first was seen on May 9th. * * * Several specimens were taken intermediate in their characteristics between auduboni and nigrifro as; some, of the size of the latter, though In color but little darker than auduboni, while some show every gradation of color between the two extremes.

The black-fronted warbler averages somewhat larger than the Audubon’s.

Nesting: Bef ore this warbler was known to be the breeding form in Arizona, 0. IV. Howard (1899) reported on two nests found in the Huachuca Mountains in 1898, and said that he had found “several nests” of Audubon’s warbiers in 1897 and 1898, all in these mountains. These were all, doubtless, nests of the black-fronted warbler. One of these was in a red fir tree about 15 feet up, and the other “was placed in the lower branches of a sugar-pine about fifty feet from the ground, and twelve feet out from the trunk of the tree. * * * The nests are very loosely constructed, being composed almost entirely of loose straws with a few feathers and hair for a lining.” One of Howard’s nests of this warbler, with four eggs, is in the Thayer collection in Cambridge. It was found in the same mountains, at an elevation of about 9,000 feet, saddled on the limb of a red spruce tree 35 feet above ground and well concealed in the foliage. It is rather a bulky nest made of shredded weed stems, fine strips of inner bark, fine rootlets and various other plant fibers, mixed with feathers of the Arizona jay, three long wing featilers of small birds and two small owl feathers; it is lined with fine fibers, horse and cattle hair, and jay feathers. Externally it measures about 3½ inches in diameter and 2½ in height; the inside diameter is about 2 inches and the cup is about 13,4 inches deep.

James Rooney has sent me the data for a set of four eggs of the black-fronted warbler, taken by Clyde L. Field in the Santa Catalina Mountains in Arizona, June 2, 1938. The nest, placed 15 feet above ground at the end of a pine limb, was made of twigs and was lined with deer hair and a few feathers. A nest with four eggs, in the collection of Charles E. Doe, in Florida, was taken by the same collector in the same mountains on June 8, 1937; it was in a crotch of an aspen, 30 feet up.

Eggs: The measurements of 16 eggs average 18.5 by 13.6 inillimeters; the eggs showing the four extremes measure 19.8 by 14.0, 19.5 by 14.4, 17.3 by 13.9, and 17.6 by 12.4 millimeters (Harris).