Male and female Black-throated Blue Warblers look so different from one another that even John James Audubon thought they were different species. Unlike many other warblers, Black-throated Blue Warblers do not molt into a different plumage in the fall, and so can be easily recognized year-round.
Male Black-throated Blue Warblers are quite aggressive in defending their nesting territory, and chases between males are very common in the spring and early summer. Individuals are solitary in the winter, and often defend the same winter territory from one winter to the next.
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Description of the Black-throated Blue Warbler
Males have dark blue upperparts, with a black face, throat, and flanks, and white underparts. They have dark wings with a white patch visible on the folded wing. Length: 5 in. Wingspan: 8 in.
Females are largely grayish-olive with a pale supercilium and a pale arc under the eye. They also have a white patch on the wing.
Seasonal change in appearance
Immatures are similar to adults, but duller, and may lack the white wing patch.
Black-throated Blue Warblers inhabit deciduous forests or mixed forests, but in migration they also occur in shrubby areas.
Black-throated Blue Warblers eat insects, but also nectar.
Black-throated Blue Warblers forage slowly in understory or low in trees.
Black-throated Blue Warblers breed in southeastern Canada, the northeastern U.S., and the Appalachians. They winter in the Greater Antilles and Central America. The population is stable to increasing.
Bent Life History
Visit the Bent Life History for extensive additional information on the Black-throated Blue Warbler.
Pairs are often faithful from one season to the next, though males can have more than one mate.
Black-throated Blue Warblers are often very tame.
The song is a long series of rising buzzes. A sharp flight call is also given.
The Tennessee Warbler somewhat resembles the female Black-throated Blue Warbler. The female Black-throated Blue Warbler has a white wing patch.
Female Cerulean Warblers have two white wing bars and somewhat resemble the female Black-throated Blue. Males Cerulean Warblers (shown here) have a white throat and cerulean blue color.
The Orange-crowned Warblersomewhat resembles the female Black-throated Blue Warbler. The female Black-throated Blue Warbler has a fine, white line above the eye and white wing patch.
The Black-throated Blue Warbler’s nest is a cup of bark strips and fibers lined with finer materials. It is placed in a fork of a thick shrub.
Color: Whitish with darker markings.
Incubation and fledging:
The young hatch at about 12-13 days and fledge at about 8-10 days, though remaining dependent on the adults for some time.
Bent Life History of the Black-throated Blue 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 Black-throated Blue Warbler – the common name and sub-species reflect the nomenclature in use at the time the description was written.
DENDROICA CAERULESCENS CAERULESCENS (Gmelin)
This neatly dressed warbler is one of our commonest migrants throughout the eastern half of the United States, but as a breeding bird it is confined mainly to the northernmost States and to extreme southern Canada, almost wholly within the Canadian Zone. Its rather long common name describes this dainty bird.
Spring: From its principal winter resort in the West Indies, the black-throated blue warbler migrates through the Bahamas and Florida to the Atlantic States and northward, along the Alleghenies and to the eastward of them, to its northeastern breedings grounds. According to Prof. W. W. Cooke (1904) the earliest arrivals usually strike the Sombrero Key lighthouse in Florida around the middle of April, although there are two or three exceptionally early records in March. As the average dates of arrival in New England and New Brunswick are only about a month later, it would seem that the migration is fairly rapid. But the dates of earliest arrival do not tell the whole story, for Frederick C. Lincoln (1939) observed this species in the mountains of Haiti in the middle of May, showing that there are always many late migrants.
Professor Cooke’s records show that this species arrives at Asheville, N. C., a few days earlier than at Raleigh, N. C., suggesting that this is one of the few species that appear in the mountains earlier than on the plains.
There is a northward migration west of the Alleghenies corresponding almost exactly in time with that along the Atlantic slope. Cooke says that “in southern Louisiana and southern Mississippi the blackthroated blue warbler is almost unknown.” He gives only very few records for any point south of Indiana, and some of these may have come across the Gulf of Mexico. The inference is that the bulk of the birds that migrate northward through the central States may have crossed the lower Alleghenies into these valleys. According to his records, it takes the birds only about 10 days to migrate from Brookville, md., to points in Ontario.
On its migration the black-throated blue warbler shows a preference for the lower shrubbery in various kinds of woodlands, but it may also be seen almost anywhere in such suitable cover in our parks and gardens or about human dwellings. Milton B. Trautman (1940) says that, in Ohio, these and the Canada warbiers “were close associates in migration and frequented the same habitat niches.”
In its summer home this warbler is even more of a woodland bird, frequenting heavy deciduous woods where there is more or less thick undergrowth of mountain-laurel, rhododendron, creeping yew, deciduous bushes, small saplings, or tiny conifers. My most intimate acquaintance with the biack-throated blue warbler was made while visiting at Asquam Lake, N. H., with Mr. and Mrs. Richard B. Harding. From their camp the land slopes downward to the shore of the lake and is heavily wooded with tall white oaks, swamp white oaks, red oaks, beeches, maples, paper birches, and other deciduous trees; there are also some white pines and hemlocks scattered through the forest, and a heavy undergrowth of mountain-laurel, striped maple, witch-hazel, and other shrubbery. The black-throated blue warblers and the veeries were the commonest breeding birds in this area.
Gerald Thayer wrote to Dr. Chapman (1907) that about Monadnock, N. H., this is “a bird of the ampler deciduous undergrowth in deep, moist woods: mixed virgin timber or very old second growth.
It is peculiarly partial to these woodland conditions, and is common wherever they occur, especially between the altitudes of 1,000 and 2,500 feet. Creeping yew is almost always common in woods where these Warblers breed, and they sometimes, perhaps often, nest in a clump of it.” And ‘William Brewster (1938) says that around Urnbagog Lake, Maine, “the local population was chiefly concentrated wherever there were extensive patches of yew (Ta ,us can adensis) .” I can find no evidence that this warbler is ever common in clear stands of coniferous trees, but is often found in mixed woods where there is a scattering of the evergreens, especially if there are small seedlings of sprdce, fir, or hemlock, in which they sometimes build their nests.
Territory: In favored regions, where the population is fairly dense, as it often is, the males arrive ahead of the females and establish their breeding and feeding territories, which they often have to defend against intruding males of the same species. John Burroughs (1895) describes such an encounter as follows: “Their battle-cry is a low, peculiar chirp, not very fierce, but bantering and confident. They quickly come to blows, but it is a very fantastic battle, and, as it would seem, indulged in more to satisfy their sense of honor than to hurt each other, for neither party gets the better of the other, and they separate a few paces and sing, and squeak, and challenge each other in a very happy frame of mind. The gauntlet is no sooner thrown down than it is again taken up by one or the other, and in the course of fifteen or twenty minues they have three or four encounters, separating a little, then provoked to return again like two cocks, till finally they withdrawn beyond hearing of each other,: both, no doubt, claimm the victory.”
Nesting: I believe that John Burroughs (1895) was the first naturalist to discover the nest of the “black-throated blue-backed warbler,” as he called it, and be wrote an interesting account of his hunt for it in “Locusts and Wild 1-Joney.” It was found in July, 1871, in Delaware County, N. Y., and contained four young and one addled egg. “The nest was built in the fork of a little hemlock, about fifteen inches from the ground, and was a thick, firm structure, composed of the finer material of the woods, with a lining of very delicate roots or rootlets.” The young birds were nearly fledged and were frightened from the nest. “This brought the parent birds on the scene in an a,,ony of alarm. Their distress was pitiful. They threw themselves on the ground at our very feet, and fluttered, and cried, and trailed themselves before us, to draw us away from the place, or distract our attention from the helpless young.”
Mrs. Harding showed me some half dozen nests of this warbler in the locality near her camp at Asquam Lake, N. H. All were in low bushes of mountain-laurel (Kabnia latifolia) from 12 to 18 inches above the ground and were not very well concealed. They were well made of strips of inner bark, canoe birch bark, straws, fern fronds, and dry leaves, and were lined with black horsehair and fine black rootlets. Altogether, Mrs. Harding (1931) found 15 nests similarly placed in low mountain-laurels, from 9 to 15 inches up, and all made of similar materials, but she says that “skunk fur is used freely as a substitute and sometimes pine needles or bits of moss,” in the lining. So far as I know, she has not found pieces of rotten wood in the nests, as commonly reported by others.
Miss Cordelia J. Stanwood, of Ellsworth, Maine, tells me that the nests she finds near her home are placed in small firs or spruces. Frederic H. Kennard mentions in his notes a Maine nest wonderfully well hidden in a clump of little spruces about one foot from the ground. He also reports two Vermont nests, one about 2 feet from the ground in a tangle of raspberry vines beside a logging road, the other about 8 or 10 inches up in a little thicket of low-growing mountain maple. Robie W. Tufts tells me that the few nests he has examined in Nova Scotia were all built in “small spruce or fir seedlings two or three feet from the ground in heavy woods of mixed or coniferous growth.”
Francis H. Allen writes to me of a nest he found in an unusual situation in Waterville, N. H.: “It was placed about a foot from the ground in the small twigs of a fallen beech, on which were the dead leaves of last season. * * * I collected the nest July 3 after the young had left it. The measurements were: Diameter, outside, 31/2 inches; inside, 2 inches; depth, outside, 2æ inches; inside, 1½ inches. It was composed mainly of fragments and shreds of dead wood, apparently stuck together by some glutinous substance, and in one place it had what seemed to be a web of some kind binding it. A few beech buds and bud scales were worked in, and a bleached leaf fragment, a shred of yellow birchbark, and a small dangling strip of canoe-birch paper: the last perhaps for ornament: completed the body of the nest. The lining was of fine black rootlets. The general effect of the outside was a light yellow or bright straw-color. It was an interesting and a beautiful nest.”
Dr. Chapman (1907) says that “nests found by Burteb (MS.) at Branchport, New York, were built in birch saplings eighteen and twenty inches from the ground, and in a blackberry bush fourteen inches from the ground.” He quotes from the manuscript of Egbert Bagg, of Utica, N. Y., who found nests very similar to the one described above by F. H. Allen. But he says that “one nest had some of the finer quills of our common procupine (even large enough for their barbs to be visible to the naked eye). This soft of lining might be satisfactory to the old bird, protected by her coat of feathers, but would seem to be somewhat dangerous to her naked fledglings.” One of his nests, evidently built in an upright fork, measured “diameter, outside, 3½ inches, inside, 21,4 inches; height, outside, 5 inches; depth, inside, 11/2 inches.”
T. E. McMullen has sent me the data for 22 nests, found in the Pocono Mountains, Pa. All of these were built in rhododendrons in woods, two on hillsides, one on the edge of a road, one on the edge of the woods, one near a creek, and three along a creek bank. Most of Mr. Brewster’s (1938) Lake Umbagog nests were placed low down in yews (Ta~u~ canaden~is). Apparently, the favorite nesting sites of the black-throated blue warbler are in the broadleaf evergreens, mountainlaurels and rhododendrons, where these are available; next in popularity come the other evergreens (spruces, firs, and hemlocks) of small size; but nests have been found in many places in deciduous seedlings, saplings and sprouts, mainly maple and beech, or in various other bushes or tangles.
Mrs. Harding gave me an account of the building of a nest, which she watched during a period of four days. Most of the work was done by the female, but the male helped shape the nest occasionally. The beginning of the nest and much of the main part of it was made of thin strips of the paperlike bark of the white, or canoe, birch firmly bound in place with great quantities of cobwebs; during the early stages of building the rim was anchored with several strands of cobweb to the surrounding leaves and twigs to secure it while the nest was being shaped; this the bird did by sitting in the nest and turning around in all directions, molding it inside with her feet and breast and pressing her tail down over the edge to smooth the exterior. The male sang in the vicinity and brought some of the material, and once he drove away another male. The nest was finished on the fourth day. This process is described in more detail in Mrs. Harding’s (1931) paper, where she notes “there is usually an interim of at least twenty-four hours before the first egg is laid. The female lays the eggs at intervals of twentyfour hours: frequently early in the morning. * * * On the morning of the fourth day when the clutch is complete the female commences incubating.”
Eggs: The black-throated blue warbler lays normally four eggs, three are not a rare complement, but five are seldom found. Richard C. Harlow tells me that in over 200 nests that he has examined he has found only 4 sets of five.
The eggs vary in shape from ovate to short ovate, rarely tending to elongate ovate, and are only slightly lustrous. They are white or creamy white, speckled, blotched, or clouded with tones of “pecan brown,” “russet,” “Mars brown,~~ “cinnamon-brown,” “chestnutbrown,” “bay,” or “auburn,” with undertones of “benzo brown,” “light brownish drab,” “light violet-gray,” or “pale Quaker drab.” There is quite a little variation in the markings, ranging from spots and undertones that are distinct and clearly defined to spots clouded together and undertones only faintly discernible. The markings are usually concentrated at the large end, often forming a loose wreath, or sometimes a solid cap of brown. Occasionally, markings are well scattered over the entire egg. There seem to be two distinct types, one having spots of two or three shades of brown, with gray undertones, the other with tones of only one shade of brown, with drab undertones. The measurements of 50 eggs average 16.9 by 12.8 millimeters; the eggs showing the four extremes measure 18.9 by 13.0, 16.7 by 13.5, 15.2 by 12.2, and 17.0 by 11.8 millimeters (Harris).
Young: The period of incubation for the black-throated blue warbler, according to Miss Stanwood’s notes, is about 12 days; and the young remain in the nest for about 10 days. Incubation of the eggs and brooding of the young is done by the female only, but feeding the young and cleaning the nest is shared about equally with the male. She saw the young fed with daddy-longlegs, white moths, caterpillars, crane-flies, mosquitoes, and many other insects.
Quoting from the notes of J. A. Farley, Mr. Forbush (1929) gives the following picture of a brooding female: “She had spread the white feathers of her lower parts out so completely over her young that there was not a vestige now visible of the four young that I had found a short time previously filling the nest so full. She ‘fluffed’ herself out so as to hide all traces of the young. * * * She made a beautiful picture. The whole effect was wonderful. The bird seemed to be sitting in a billowy mass of eider down, or cotton wool, that swelled, or rather bulged, up all around her, a regular bed of down.”
Mrs. Nice (1930b) watched a brood of young black-throated blue warblers, in Pelham, Mass., for 7 consecutive days, June 24 to 30, and for a total of 361/2 hours. During this time the female fed the young 193 times and the male, 201 times; the average feeding time was once in 5.6 minutes; the female brooded 22 times, a total of 200 minutes, mainly in the earlier half of the period; the feces were eaten by the female 6 times and by the male 13 times; they were carried away by the female 47 times and by the male 67 times.
As to the food of the young, Mrs. Harding (1931) writes:
As soon as the young hatch the female begins feeding them. I have seen no evidence of regurgitation. She thoroughly crushes caterpillars, etc., between her mandibles before giving them to the young. Their food for the first day consists of small insects, soft white grubs and a large number of half inch, smooth, green caterpillars, which are found on hemlock trees. From the second to the eighth day their diet consists chiefly of small green caterpillars, insects, white grubs and an occasional may-fly or gray and cream colored caterpillar without spines. On the ninth and tenth day their diet still Includes white grubs and green caterpillars, but dragon flies and may-flies are the chief staples. Slugs, winged ants, white cabbage butt~rfiies and moths are also on the menu.
From the time the young hatch until they are five days old the parents swallow the faecal sacs. After that they carry them away from the nest and place them on the branches of neighboring trees: frequently using dead branches.
She gives a detailed account of the development of the young and their manner of leaving the nest naturally on the tenth day. During the 6 days when she thought it safe to handle them without driving them out of the nest too soon, one increased in weight from 22 grains to 141, and another from 24 to 147 grains.
Plumages: The sexes differ slightly in the juvenal plumage. The young male is olive-brown above; the wings are blackish, the primaries edged with bluish-leaden-gray; the wing coverts, secondaries, and tertials are margined with olive-green, and there is a white patch near the base of the primaries, as in the adult; the tail is much like that of the adult; the under parts are brownish, tinged with yellowish on the throat and abdomen; the lores and two submalar streaks are dusky, and the superciliary stripe is yellowish white. The young female is similar, but has dull brown wings and tail with greenish instead of bluish edgings, and the white area in the primaries is smaller, more dingy and sometimes obscure.
A partial postjuvenal molt occurs in late July and August involving the contour plumage and the wing coverts but not the rest of the wings or the tail, producing a first winter plumage in which the sexes become decidedly differentiated and not very different from the adults at that season. This is one of the few wood warblers in which the fall plumage is very much like the spring dress. In the young male the blue of the upper parts is not as clearly blue as in the adult; the feathers of the back are faintly edged with olive-green, those of the black throat veiled with dull whitish, and the abdomen is tinged with yellowish. The young female differs from the fall adult in being greener above, without bluish tinge, and more huffy or yellowish below.
There is a limited prenuptial molt about the head, and wear has removed most of the edgings and fading has made the under parts clearer. At this age, young birds can be distinguished from adults by the worn and dull brown wings and tail. Subsequent molts and plumages, in which young and old are alike, consist of a complete postnuptial molt in July and August and a limited prenuptial molt about the head. The adult male in the fall is only slightly tipped with greenish above and with whitish on the black throat, which may be somewhat less in extent.
Food: No thorough study of the food of the black-throated blue warbler seems to have been made, but probably all of the items mentioned as food for the young are also eaten by the adults. Forbush (1929) adds the hairy tent caterpillar, flies, beetles, and plant lice. Aughey (1878) found 23 locusts and 15 other insects in one stomach collected in Nebraska. Dr. Wetmore (1916) reports on the contents of eight stomachs collected in Puerto Rico, in which animal matter formed 75.5 percent and vegetable matter 24.5 percent of the food. “The vegetable food was found in the three stomachs taken in December and January and consisted of seeds of the camacey (Miconia prasina) .” The principal items in the animal food were lantern flies (Fulgoridae), 19.46 percent, various weevils, 14.25 percent, flies, 10.09 percent, and spiders, 12.62 percent. A few beetles and one ant were eaten. Most of the food consisted of harmful insects.
Behavior: The black-throated blue warbler is one of the tamest and most confiding of all our wood warblers. I was able to photograph (p1. 30) the female incubating and both sexes feeding the young at very short range without any special concea]ment; they are very devoted parents and show great concern when the safety of their young is threatened, trailing along the ground with the broken-wing act in great distress.
Gerald Thayer wrote to Dr. Chapman (1907) : “In its movements the Black-throated Blue is more deliberate than many of its relatives, but it has at the same time a somewhat Redstart-like way of ‘spiriting’ itself from one perch to another, and, while perched, of partly opening its white-mooned wings ;: a habit and a marking shared by the boldly blue-and-black-and-white males and the dimly green and yellowish females and young.”
Henry D. Minot (1877) writes:
They are very dexterous in obtaining their insect prey; sometimes seizing it In the air, with the skill of a true Flycatcher, and at other times finding it among the branches of the various trees which they frequent. Now they twist their heads into seemingly painful postures, the better to search the crannies in the bark or blossoms, now spring from a twig to snap up an insect in the foilage above their heads, instantly returning, and now flutter before a cluster of opening leaves, with the grace of a Hummingbird. Occasionally they descend to the ground, and are so very tame that once, when I was standing motionless, observing some Warbiers near me, one hopped between my feet to pick up a morsel of food.
Voice: Aretas A. Saunders has sent me the following study of the song: “The song of the black-throated blue warbler, in its more typical forms, is one of only three or four slowly drawled notes in a peculiarly husky voice, the last note commonly slurred upward. While the number of notes in the songs varies in my 41 records from two to seven, more than half of them are of only three notes, and most of the others are of four or five. In all, 22 songs end with the upward slur of the last note, 14 in an unslurred note and 5 in a downward slur.
The general trend of the pitch is upward in 29 records, downward in 10, and ending in the same pitch as the first note in 2.
“The pitch of songs varies from G”‘ to E””, a range of four and a half tones. Single songs range from half a tone to three tones, the majority covering one and a half or two tones. The length of the songs is from 11/s to 2 seconds. This indicates the slowness of the three or four notes, for other warbler songs with twice as many notes are about the same length. In the few songs of this bird that have more notes the notes are shorter and faster, so that the songs are not Ion crer.
“This species shows a greater tendency to sing unusual songs than most warblers. On three occasions I have heard a warbler song that I could not recognize, and when I located the bird, found it to be a black-throated blue.
“Two of these songs were of rapid notes, in a clear, ringing quality, not at all like the ordinary song of this bird. The third was two rather long notes in a clear, sweet wbistle, the second higher in pitch than the first, so that it resembled the phoebe whistle of the chickadee reversed.
“The average date of the last song in 14 summers in Ahlegany State Park is July 21. The earliest is July 14, 1927 an 1940, and the latest July 29, 1931. The song is rarely revived in Au~ust, after the molt.”
Francis II. Allen (MS.) writes the two common songs as “quee quee quee-e-e'” and “que-que-que-gue quee-ee’,” and says further, “in June 1907, I heard a bird in Shelburne, Vt., that sang persistently a short song like kii quee-e-e’ besides singing occasionally one of the ordinary songs. In May, 1910, at Jaifrey, N. H., I heard a bird sing over and over qui-qui-qui-qui-qui-qni-qu.i-qui-quee’, but most of the birds of the region seemed to sing zee 2ee zee-ee, with a falling inflection, while some sang the ordinary quee quee quee-e-e’, with rising inflection. The quee songs have a nasal tone. The call note is a dry chut or chet, resembling the chip of the black-throated green but not so thick.”
Mrs. Nice (1930b) describes four different songs; and Gerald Thayer, in Chapman (1907), gives four main songs, with variations, but the versatility of this singer seems to be well enough shown in the previous descriptions.
Field marks: The Inale black-throated blue warbler could hardly be mistaken for anything else; there is no other American warbler that is at all like it. The blue back, the extensive black throat, the white patch iiear tbe bases of the primaries, the white under parts, and the white spots on the inner webs of the three outer tail feathers are all diagnostic. Fortunately, the fall plumage is essentially the same. But the female is one of the most difficult of the warblers to recognize, olive-green above and buffy below; the only distinctive marks are the white patches in the wings and tail, similar to those of the male, but smaller, duller, and sometimes obscure.
Fall: As soon as the molting season is over, late in August, old and young birds begin to drift away from their summer haunts; most of them depart from New England during September or even late August. Birds from New England and farther north pass through the Atlantic Coast States to Florida and the West Indies, while those from the interior migrate slightly southeastward and across the lower Alleghenies to join them. Professor Cooke (1904) writes:
‘Black-throated blue warblers strike the lighthouse at Sombrero Key in greater numbers than any other kind of bird, particularly during the fall migration. * * * In five years’ time they struck the llgbt on seventy-seven nights, and as a result 450 dead birds were picked up on the platform under the lantern. Probably a still larger number fell Into the sea. Adding to these those that were merely stunned and that remained on the balcony under the light until able to resume their journey, the keeper counted 2,000 birds that struck. There were two nights, however, when the numbers of this species were so great that no attempt was made to count them. The Fowey Rocks lighthouse was struck on thirty different nights. It is certain, therefore, that the black-throated blue warbler passes in enormous numbers along both coasts of southern Florida.
Winter: Professor Cooke (1904) observes that “the winter home of the black-throated blue warbler is better defined than that of any other common warbler, and allows a very exact determination of the square miles of territory occupied by it at this season. Cuba, Haiti, and Jamaica, with a combined area of 74,000 square miles, are doubtless occupied during the winter by the great majority of the individuals of the species. The remaining birds do not probably cover enough territory to bring the total to 80,000 square miles. This is a small area compared with that occupied during the breeding season.” In his Birds of Cuba, Dr. Thomas Barbour (1923) writes:
The Black-throated Blue Warbler is excessively common, early to arrive and late to leave. It is one of the tamest and most confiding species, and one to be found In all sorts of situations. Early pleasant days in Cuba spent at Edwin Atkins’ plantation, Soledad, near Clenfuegos, brought a great surprise, for I found It not uncommon to have these little Warbiers enter my room through the great ever open windows and flit from couch to chair. This happened often, notably at Guabairo, not far from Soledad. So inquisitive and confiding are they, that one can hardly recognize the rather retiring dweller in woodland solitude which we know in the North.
Range: Eastern North America, from southern Canada to northern South America.
Breeding range: The black-throated blue warbler breeds north to southwestern and central Ontario (Lac Seul, Kapuskasing, and Lake Timiskaming); and southern Quebec (Blue Sea Lake, Quebec, Godbout, and Mingan). East to southern Quebec (Mingan, Grand Gr~ve, and the Magdalen Islands) ; eastern Nova Scotia (Cape Breton Island and Halifax); southern Maine (Ellsworth and Auburn); southeastern Massachusetts (Taunton) ; Connecticut (Hadlyme) ; northeastern Pennsylvania (Lords Valley and Pocono Mountain); and southward through the Alleghanies to Northwestern South Carolina (Mountain Rest); northeastern Georgia (Rabun Bald, Brasstown Bald, and Young Harris). South to northern Georgia (Young Harris) ; southeastern Tennessee (Beersheba Springs) ; southeastern Kentucky (Log Mountain and Black Mountain); northeastern Ohio (Wayne Township and Pymatuning Bog); northern Michigan (Douglas Lake and Wequetonsing); northern Wisconsin (Fish Creek, Mamie Lake, and Perkinstown); and northern Minnesota (Kingsdale, Cass Lake, and White Earth; possibly sometimes near Minneapolis). West to northern Minnesota (White Earth) and western Ontario (Lac Seul). The species very probably breeds rarely in Manitoba or Saskatchewan where there are as yet only a few records and it is a recent arrival. At Emma Lake, Saskatchewan, 40 miles north of Prince Albert, 5 were observed June 27 to July 2, 1939. The first record for the Province was a specimen collected on October 21, 1936, at Percival, 100 miles east of Regina. It is a rare but tolerably regular migrant through eastern North and South Dakota, suggesting that there is some as yet unknown breeding area. The species has been recorded in migration, more often in fall, in Wyoming, Colorado, Nebraska, Kansas, Oklahoma, and Texas.
Observers at Aweme, Manitoba, in 38 years recorded it only twice. Another observer at Eastend, southwestern Saskatchewan, recorded it for the first time on September 21, 1937, after at least twenty years of continuous observation.
On the basis of such information it seems probable that the species is slowly spreading its breeding range westward.
Winter range: The principal winter home of the black-throated blue warbler is in the West Indies where it is found north to the Bahamas (Andros, Nassau, and Watling Islands). East to Puerto Rico (Rio Piedras) and the Virgin Islands (St. Croix). South to Puerto Rico (Maricas) ; Hispaniola (Paraiso, Dominican Republic; and J&~mie, Haiti) ; Jamaica (Spanishtown) ; and the Swan Islands. West to the Swan Islands; Cozumel Island; Cuba (Habana) ; and the Bahamas (Andros). It is also casual north to southern Florida (Sanibel Island, Key ‘West, and Sombrero Key); accidental in Guatemala (Cob4n) ; and in northern South America; Venezuela (Ocumare and Rancho Grande); and Cclombia (Las Nubes, Santa Marta region, and Pueblo Viej o). The species as outlined is divided into two subspecies or geographic races. The black-throated blue warbler (D. c. caerzdescen~) is found in Canada and in the United States south to Pennsylvania; Cairns’ warbler (D. c. cair’nsi) breeds in the Appalachian Mountains from southwestern Pennsylvania southward.
Migration: Late dates of departure from the winter home are: Puerto IRico: Consumo, April 3. Haiti: Morne ~i Cabrits, May 6. Cuba: Habana, May 11. Bahamas: Cay Lobos, May 14.
Early dates of spring arrival are: Florida: Fort Myers, March 4. Georgia: Fitzgerald, April 11. South Carolina: Spartanburg, April 5. North Carolina: Weaverville, April 19. Virginia: Lynchburg, April 21. District of Columbia: Washington, April 19. Pennsylvania: Swarthmore, April 25. New York: New York, April 28. Massachusetts: Amherst, May 2. New Hampshire: East Westmoreland, April 29. Maine: Auburn, May 3. Novia Scotia: Scotch Lake, May 7. Quebec: Quebec, May 7. Louisiana: New Orleans, March 22. Tennessee: Chattanooga, April 14. Kentucky: Lexington, April 24. Illinois: Urbana, April 26. Ohio: Canton, April 22. Michigan: Battle Creek, April 28. Ontario: Reaboro, May 3. Missouri: St. Louis, April 18. lowa: Sigourney, April 21. Wisconsin: Ripon, April 28. Minnesota: Hibbing, May 8.
Late dates of the departure of transients in spring are: Florida: Daytona Beach, May 21. Georgia: Darien, May 20. South Carolina: Clemson (College), May 15. North Carolina: Raleigh, May 19. Virginia: Charlottesville, May 22. District of Columbia: Washington, May 30. Pennsylvania: Berwyn, June 3. Ohio: Ashtabula, May 29. Indiana: Fort Wayne, June 2. Michigan: Detroit, June 2. Illinois-Lake Forest, June 8. Wisconsin: Racine, June 4. Iowa: National, May 27.
Late dates of fall departure are: North Dakota~: Fargo, October 21 (bird banded). Minnesota: Minneapolis, October 3. Wisconsin: Milwaukee, October 16. lowa: Sigourney, October 20. Illinois: Chicago, October 25. Michigan: Grand Rapids, November 1. Indiana: Indianapolis, October 14. Ontario-Port Dover, October 27. Ohio: Medina, October 30. Kentucky: Eubank, October 22. Tennessee: Athens, October 18. Mississippi: Gulfport, October 12. Quebec: Montreal, October 15. New Brunswick: Saint John, October 11. Maine: Portland, October 17. New Hampshire: Water Village, October 8. Massachusetts-Cambridge, November 7. New York: Fire Island, October 24. Pennsylvania: Harrisburg, October 24. District of Columbia: Washington, October 29. Virginia: Lexington, October 15. North Carolina: Highlands, November 14. South Carolina: Clemson (College), October 17. Georgia: Athens, November 2. Florida: Fernandina, November 15.
Early dates of fall arrival are: Wisconsin: New London, August 23. Michigan: Grand Rapids, August 26. Ohio: Toledo, August 24. Illinois: La Grange, August 24. District of Columbia: Washington, August 21. Virginia: Charlottesville, September 12. North Carolina: Mount Mitchell, September 1. South Carolina: Mount Pleasant, August 30. Georgia: Savannah, August 28. Florida: Coconut Grove, August 29. Cuba: Cienfuegos, September 2. Dominican Republic: El Rio, October 5. Puerto Rico: Las Marias, October 12.
Casual records: On the Farallon Islands, Calif., a specimen was found dead on November 17, 1886; it had been previously observed for three weeks. In New Mexico a specimen was taken at Gallinas Mountain on October 8, 1904, and on October 9, 1938 another was collected in Milk Ranch Canyon near Fort Wingate. In Bermuda a specimen was collected October 2, 1902; and it is considered a rare winter visitor. An individual spending the winter at a feeding stand in the suburbs of Washington, D. C., was observed closely from December 22, 1930, to January 16, 1931.
At sea the black-throated blue warbler has been observed on October 27, 1921, 12 hours run out from Port-au-Prince, Haiti, toward New York; and on March 29, 1918, in the Gulf of Mexico, 125 miles from Sabine Pass, La.
Destruction, at lighthouse&: Lighthouses with fixed white lights have caused considerable destruction of bird life during migration and the black-throated blue warbler seems to have been especially lured to those in southern Florida. Records were received from several of these lighthouses over a period of 5 or 6 years. Those from Sombrero Key are most detailed and give an interesting picture of migration at that point, since they include date, weather conditions, number of birds that struck, number killed, and hours during which the birds struck the light.
Comparatively fewer birds struck the light in spring than in fall. The spring dates are from March 9 to May 29; but in 4 years birds are reported to have struck the light only on 24 nights and 4 individuals is the greatest number reported.
In the fall, the records extend from September 3 to December 5, the heaviest nights being from the middle of September to late October. In two different years birds struck the light on 19 nights in two months. The greatest number in one night was 400 with 56 killed. In one of those years 1146 birds struck the light; of these 193 were killed. It was not only on stormy nights that the birds were attracted, as 130 struck and 15 were killed on a night described as calm and dark. Sometimes they kept striking all night, but on others the flight seems to have been concentrated, as when 300 birds struck in 31/2 hours. On a few occasions the mortality was as high as one-third of the birds that struck.
On the night of January 26, 1880, two birds struck the light. These were either wintering birds or extremely early migrants.
Egg dates: Massachusetts: 6 records, May 28 to July 5; 3 records, June 2 to 8.
New Hampshire: 17 records, June 3 to 22; 9 records, June 10 to 15. New York: 51 records, May 29 to June 20; 37 records, June 3 to 12, indicating the height of the season.
Pennsylvania: 57 records, May 25 to June 20; 32 records, May 30 to June 6.
North Carolina: 10 records, May 5 to June 22; 6 records, June 4 to 11.
Virginia: 19 records, May 26 to June 18; 14 records, May 27 to June 4 (Harris).
DENDROICA CAERULESCENS CAIRNSI Coues
This local race of the black-throated blue warbler, breeding in the southern Alleghenies, was named by Dr. Elliott Coues (1897) in honor of its discoverer and original describer, John S. Cairns of Weaveryule, N. C. Dr. Coues, at that time, mentioned only the characters of the male, but those of the female are fully as well, perhaps more satisfactorily, marked than those of the male. Ridgway (1902) describes both very well and concisely as follows:
“Similar to D. c. caerulescens, but adult male darker above, especially the pileum, which is not lighter blue than the back, the latter usually more or less spotted or clouded with black, sometimes chiefly black, the pileum sometimes streaked with black; adult female darker and duller olive above and less yellowish beneath, with the olive of flanks darker and more strongly contrasted with the pale oliveyellowish of abdomen.” In discussing its distribution, he was unable to define its breeding range with any degree of accuracy; and adds in a footnote: “On the whole, the form is not a very satisfactory one, one of the two characters on which it was based (smaller size) failing altogether (D. c. cairn3i averaging slightly larger, in fact, than D. c. caerulescen3), and the other only partially so, since many specimens of D. c. cairnsi have little if any black on the back, while many of D. c. caerule8cen8 have quite as much as the average amount shown in D. c.
The 1931 A. 0. U. Check-List gives the breeding range of cairnsi as from Maryland to Georgia, but no definite line can be drawn; birds from southern Pennsylvania and Maryland, and perhaps the Virginias, are variably intermediate in their characters, and specimens can be found that are referable to either one or the other form.
Before this race had been separated from the northern form, Cairns (1896) wrote of its haunts:
High up on the heavily timbered mountain ranges of western North Carolina Is the summer home of the Black-throated Blue Warbler.
Here in precipitous ravines, amid tangled vines and moss-covered logs, where the sun’s rays never penetrate the rank vegetation and the air is always cool, dwells the happy little creature, filling the woods from dawn to twilight with its song. * * *
These birds are a local race; breeding from one generation to another. They arrive from the south nearly ten days earlier than those that pass through the valleys on their northward migration. It is common to observe migrants through the valleys while breeders on the higher mountains are already nest-building and rearing their young.
This statement agrees with Professor Cooke’s (1904) later data, and with his statement: “The species is one of the few that appear in the mountains earlier than on the plains, and the case seems to sustain the theory that the individuals of a species that breed farthest south are the first to migrate in the spring.”
Nesting: Cairns (1896) writes on this subject:
Nesting begins in May and continues until the end of June. The nests are placed In various shrubs, such as laurel, wild gooseberry, and chestnut, but the blue cohosh or papoose-root (Caulcvpl&yllum thalictroides) seems to be the favorite. These thick weeds grow rapidly to a height of from three to five feet, entirely hiding the ground, and thus afford the birds considerable protection. * * * The nests are never placed over three feet from the ground; usually about eighteen Inches; one I examined was only sIx inches. * * ï The nests show little variation in their construction, though some are more substantially built than others. Exteriorly they are composed of rhododendron or grape-vine bark, Interwoven with birch-bark, moss, spider-webs, and occasionally bits of rotten wood. The Interior Is neatly lined with hair-like moss, resembling fine black roots, mixed with a few sprays of bright red moss, forming a strikingly beautiful contrast to the pearly eggs. The female gathers all the materials, and builds rapidly, usually completing a nest in from four to six days if the weather is favorable. She is usually accompanied by the male, which, however, does not assist her In any way.
Bruce P. Tyler of Johnson City, Tenn., has sent me some fine photographs (p1. 31) of the nests of this warbler, and says in his notes: “The Cairns warbler is found breeding in May, and later, on the southerly slope of Beech Mountain, just across the Tennessee line in North Carolina, at an elevation of 4,800 to 5,200 feet above sea level. The nest is built in small upright saplings or sprouts, 3 to 4 feet above the ground, and is constructed of shredded bark from the dying chestnut trees, rotten wood, etc., bound together with spiders’ webs, and lined with fern rootlets and fine grass.”
Thomas D. Burleigh (1927a) records four nests found, during May and June, on the slopes of Brasstown Bald in the northeastern part of Georgia: Two of these were in laurel bushes, 2 and 2½ feet from the ground; another was 2 feet up in the fork of a small viburnum; and the fourth was 5 feet from the ground, “saddled near the end of a drooping limb of a rhododendron at the base of a large yellow birch well up the mountainside.” A nest in my collection was taken by H. H. Bailey in Giles County, Va., at an elevation of 4,000 feet, on May 22, 1914; it was placed in a horsechestnut sprout alongside of a road, 1 foot above the ground. This and another nest before me are very similar to those described above.
Eggs: The 3 or 4 eggs laid by Cairn’s warbler are practically indistinguishable from those of the black-throated blue warbler. The measurements of 30 eggs average 17.3 by 12.7 millimeters; the eggs showing the four extremes measure 19.0 by 13.0, 17.9 by 13.4, and 16.0 by 12.0 millimeters (Harris).