Bay-breasted Warbler

BREEDING MALE

Female

Seasonal change in appearance

Juvenile

Habitat

Diet

Bay-breasted Warblers eat insects and berries.

Photograph © Greg Lavaty.

Behavior

Range

Fun Facts

Vocalizations

Attracting

Nesting

Bartram’s “Little Chocolate-breasted Titmouse” was given the above name by Wilson (1832), based on a specimen taken in eastern Pennsylvania. Both he and Audubon considered it a rare species and had little to say about it. This is not strange, for they probably never saw it on its breeding grounds and probably overlooked it on its rather rapid migrations, or perhaps confused it with others in the host of migrants. To see the bay-breasted warbler to advantage one must visit the coniferous forests of northern New England and southern Canada east of the Great Plains; here it is often an abundant bird, and in some places it is the commonest of the warblers.

In Maine, according to Ora W. Knight (1908), “the species is rare and local, even in migration, and as a summer resident is chiefly confined to the deeper wilder sections of the State within the Canadian fauna. * * * The few pair that remain to nest in southern Penobscot County are to be found in the low, rather swampy maple and birch growth, mixed with firs and spruces. * * * In northern Maine I have met with the species in the rather swampy evergreen or mixed growth about the ponds and lakes and judge these localities are their favorite haunts.”

Of its range in New Hampshire, Dr. Glover M. Allen (1903) writes: “In the White Mountains and northward it is a fairly common summer resident mainly of the upper Canadian zone. The range of this species in summer overlaps that of the Black-poll Warbler for about 1,000 feet, and extends below it to nearly an equal amount. Thus one finds breeding birds at an altitude of from 1,800 feet in rich, damp coniferous woods on southern exposures, up to about 4,000 feet among the small balsam timber.”

Spring: How the hay-breasted warbler reaches the coast of Texas from its winter home in Colombia and Panama seems to be unknown. Alexander F. Skutch tells me that it is perhaps only an accidental transient in Central America north of the Isthmus of Panama. It seems to be unknown in Mexico, but George G. Williams (1945) lists it among the warblers that occur regularly and frequently along the coast of Texas each spring. I saw it in the wave of migrating birds that I observed on an island in Galveston Bay on May 4,1923. In order to avoid Mexico, it may fly partially across the Gulf of Mexico, or perhaps it may fly only along the coastline. It has also been observed flying directly across the Gulf from Yucatán to the Gulf States. Dr. Chapman (1907) says:

On the way to its summer home, the bird shuns Mexico, the West Indies, and the United States south of Virginia, east of the Allegheny Mountains; the great bulk passes north through the Mississippi Valley, west to eastern Texas (Corpus Christi, Port Bolivar), Missouri (Freistart), and Iowa (Grinnell) casual or accidental in South Dakota (May 1888), Montana (Big Sandy, May 24, 1903), and Alberta (Medicine Hat). * * * Although close observation will reveal the presence of Bay-breasts during both the spring and fall migrations, they are generally to be classed among the rarer Warblers the mere sight of which is stimulating. Occasionally, however, the weather so affects their migration that they come en masse and for a brief period are actually abundant.

William Brewster (1906), referring to the Cambridge region of Massachusetts, writes: “During the spring flight northward, which passes late in May, they usually occur singly and in dense woods, especially such as consist largely of white pines, hemlocks or other coniferous trees. A remarkable exception to this rule happened in 1872. On May 26 of this year several birds were seen in the heart of Cambridge, and on the following morning I found upwards of forty, most of them females, feeding in the tops of some large oaks.” This is about as far east as the bay-breasted warbler usually comes in Massachusetts; it is an exceedingly rare bird in the southeastern corner of the state; I can count on the fingers of one hand all that I have ever seen there. Most of the birds probably pass up the Connecticut Valley, or farther westward.

Nesting: It was while I was visiting with Mr. and Mrs. Richard B. Harding at their summer camp on the shore of Lake Asquam, N. H., that I saw my first and only nest of the bay-breasted warbler. The nest was placed on a horizontal branch of a white pine standing on the edge of a clearing in heavy mixed woods, within 20 yards of a cottage, and it was about 30 feet above the ground. On June 5, 1930, the nest was not quite finished. On June 8, Mr. Harding climbed the tree and found that the nest contained two eggs, but on the sixteenth the nest was empty, and was taken. Mrs. Harding described it in a letter to me as being made largely of coarse, dried grass stalks, with a few hemlock twigs and a piece of string — a loosely built structure, with straws and twigs protruding from it on all sides. The inner wall of the nest was made of dried grasses and pine needles, with a thin lining of fine, black rootlets and horsehairs.

Miss Cordelia J. Stanwood has sent me some extensive notes on the home life of this warbler, in which she describes the building of the nest as follows: “First a few culms of hay were placed in the fork of several twigs on a flat limb; next fine spruce twigs were anchored to the various points of attachment, and the nest shaped of these. The lining consisted of a very few runners of cinquefoil, a very few pine leaves, and much horsehair and human hair.”

Philipp and Bowdish (1917) during two seasons in New Brunswick found nine nests of the bay-breasted warbler. Of the six nests found in 1915, all “were in small spruces, two of them being well out on horizontal limbs, the others close to the trunk, at heights varying from four to ten feet. None were very well concealed and some of them were remarkably open, but they blended so well with their surroundings that they were exceedingly difficult to discern. All of the nests of this species that we found resemble large structures of the Magnolia Warbler, being rather loosely constructed, of fine spruce of similar twigs, exteriorly, a little dead grass and some insect webs entering into the composition, and fine, black rootlets being commonly used as a lining.” Two of the nests found in 1916 were higher up; one was “fifteen feet from ground, supported by two horizontal branches, against the main stem of a small balsam, near its top, in a clump of same, in partial clearing in spruce forest.” The other was “twenty feet up against the trunk of a spruce tree at the edge of a clearing. This latter nest was in a very thick portion of the foliage and absolutely invisible from the ground, being found only by flushing the bird.” F. H. Kennard mentions in his notes several nests, found in New Hampshire, that were from 25 to 40 feet up, “in the lower, outreaching branches of tall spruces.” William Brewster (1938) mentions one that was 50 feet up.

A nest before me, taken by Richard C. Harlow in New Brunswick, was placed 12 feet up and 10 feet out toward the end of a long horizontal limb of a small, slender spruce in a high, dry spruce forest It is very well and compactly made, mainly of fine spruce twigs firmly woven into a solid and fairly smooth rim, with only a few fine grasses woven in. It is neatly and smoothly lined with a thick bed of the finest black rootlets. The nest was so placed that another limb was only two inches directly above it.

The measurements of several recorded nests vary from 2 to 2¾ inches in outside depth, from 1¼ to 1½ in inside depth, from 4 by 3½ to 5 2/3 in outside diameter, and from 2 1/10 to 2½ inches in inside diameter, according to Mendall (1937).

Eggs: The bay-breasted warbler lays large sets of eggs, from 4 to 7, but 5 is by far the commonest number, though sets of 6 are not very rare. The eggs vary in shape from ovate to elongate ovate and they are slightly glossy. The ground color is white, creamy white, pale bluish white or pale greenish white. They are handsomely speckled, spotted and blotched with “auburn,” “bay,” raw umber,” “argus brown,” “chestnut,” “chestnut-brown,” “Mars brown,” or “snuff brown,” with underlying spots of “light Quaker drab,” “light mouse gray, “deep brownish drab,” “vinaceous drab,” or “light purplish drab.” There is a wide variation in the manner of markings, some being spotted with the reddish browns, others with shades of “Brussels brown” or “snuff brown.” Then too, eggs may have two or three shades of brown mixed with the undertones of drab; or they may be marked only with tones of a single shade of brown and drab. Generally they are boldly spotted, sometimes with a few scrawls of black; while the coloring is concentrated at the large end, there is less tendency to form a distinct wreath than in many other warbler eggs. The measurements of 50 eggs average 17.7 by 12.9 millimeters; the eggs showing the four extremes measure 19.0 by 13.4, 18.0 by 13.5, 16.4 by 13.3, and 17.5 by 12.3 millimeters (Harris).

Young: Howard L. Mendall (1937) gives the following summary of his study of the home life of the bay-breasted warbler:

The period of incubation was observed to be slightly over twelve days, and the eggs hatched at intervals, with more than two days between the hatching of the first and the fifth egg. Two young left the nest at eleven days of age. Incubation and brooding apparently are carried out solely by the female, which is, at least part of the time, fed on the nest by the male. Daring the observation periods from June 28 to July 3 (when there were five young in the nest), the female averaged 26.4 feedings per hour, while the male fed on the average of 18 times an hour. However, under certain conditions and for short periods of time, the male performed a much greater proportion of the nesting duties. Both adults and one of the young were still together in the vicinity of the nest eight days after the home had been forsaken.

He observed that, during a heavy thundershower, the female stood over the young and sheltered them with her wings spread over the sides of the nest; on a hot, sunny day she protected them from the heat of the sun in a similar manner. Two of the young were killed by a red squirrel and the last one disappeared before leaving the nest. Only the first two to leave the nest survived.

Miss Stanwood’s notes contain the following account of the activities of the young a day or two before leaving the nest: “One little bird after another pushed his way to the top of the bird heap, pecked at the oil gland situated on the rump, wet his beak with oil, then dragged one wing up slowly and oiled one feather at a time, pulling the feather firmly through his beak from the root to the tip. Thus he made his feathers waterproof and beautiful; thus, also, he removed those annoying quill casings. After moistening his beak with oil the bird rests; after preening a wing the bird rests again; then he moistens his beak once more, rests, then preens the other wing and rests. The bird may have been fed a number of times while this process is going on. After feeding once more, and after the parent has again carried away the excreta, he is thoroughly rested and his toilet is in perfect condition. He is now ready to let another little warbler press to the top of the nest in his place.”

Plumages: Miss Stanwood (MS.) refers to the natal down as brown. Dr. Chapman (1907) describes the nestling in juvenal plumage as “above grayish olive, the head sometimes paler, nearly buffy, back heavily spotted with wedge-shaped black marks; below whitish thickly spotted with rounded black marks; median wing-coverts broadly tipped with white or buffy white on both webs, the greater coverts, on only the outer web.”

A partial postjuvenal molt, involving the contour plumage and the wing coverts but not the rest of the wings or the tail, occurs in July and August and produces the first winter plumage. Dr. Dwight (1900) describes the young male in this plumage as “above, yellowish olive-green, with dusky streaks on the crown, a few concealed black spots on the back, the upper tail coverts cinereous gray. Wing coverts edged with olive-green and two broad wing bands white tinged with yellow. Below, cream-color washed with straw-yellow on the throat and with a very little chestnut on the flanks.” It resembles the young blackpoll, but is “a yellower olive above, a buffier yellow below and a wash of chestnut on the flanks, with less definite streaking above and none below.” The female is distinguishable from the male in the first winter plumage, “which is a clearer green without the crown streaks of the male, the black spots on the back duller and usually even a trace of chestnut is lacking on the flanks.”

The first nuptial plumage is acquired before the birds come north by a partial prenuptial molt “which involves most of the body plumage and wing coverts but not the rest of the wings nor the tail. The deep chestnut crown, paler throat and lateral stripes, black sides of the head and forehead, olive-gray back streaked with black, the rich buff patches on the sides of the neck and the black wing coverts, plumbeous-edged and white-tipped, are all assumed.” Adults and young are now practically indistinguishable, except for the worn and duller wings and tail in the young bird. The female has the same color pattern as the male but the colors are much duller and there is less chestnut.

Adults have a complete postnuptial molt, mainly in July. Dr. Dwight (1900) describes the plumage of the winter male as “similar to first winter dress, but the crown, nape and back distinctly streaked with black, creamier tints below and the flanks striped distinctly with chestnut, the wings and tail blacker and the edgings grayer rather than greener as in the young bird; a few chestnut feathers sometimes appear on the throat and crown.” The adult female in winter is similar to the first winter female, “but whiter below, with a wash of chestnut on the flanks and with crown streaks and the dorsal spots better defined, resembling closely the male first winter dress, although usually rather duller.”

The prenuptial molt of adults is similar to that of young birds.

Food: Like other wood warblers, the bay-breasted is almost wholly insectivorous, indulging occasionally, perhaps, in a little wild fruit. No intensive study of its food seems to have been made. Edward H. Forbush (1929) says that “it takes locusts, caterpillars, ants, beetles and leaf-hoppers.” Miss Stanwood (MS.) saw moths and other insects and their larvae fed to the young.

Behavior: At the nest studied by Mr. Mendall (1937):

The adult birds showed a remarkable degree of adaptability in the face of the four changes in location to which the nest was subjected. In fact, for a species of the woodlands, the Bay-breasted Warbler appears to be exceedingly tame and unsuspicious in the presence of man. * * * She was reluctant to leave the nest, even when I had climbed within three feet of her, and it was not until the branches had been pulled to one side that she departed. Injury-feigning was very much in evidence. The bird dropped to a lower limb of the tree and almost literally crawled through the foliage in front of me. The left wing was extended and drooped, the tail was twisted to the left and the feathers spread. The bird uttered no sound, but continued to move through the branches for about fifty seconds after which she flew around me, several times coming very close to my head, and scolded violently. This protest brought the male to the scene and he joined his mate in uttering notes of alarm, though with less vigor.

Voice: Aretas A. Saunders contributes the following study: “The song of the bay-breasted warbler is much like that of the blackpoll in high pitch and quality, and in having little or no change in pitch throughout. The time, however, is not even and regular; short and long notes are alternated or irregularly mixed. There is no definite increase in loudness.

“I have only 18 records of this song, as the bird is uncommon and seems to sing less frequently on migration than the other species. Six of these songs show no change in pitch, while the others change but slightly, half a tone to a tone. The pitch in the different songs varies from B ‘ ‘ ‘ ‘ to E ‘ ‘ ‘ ‘, a range of only two and a half tones. A larger number of records would probably show a greater range than this.

“All but one of my records are from migrating birds. in Connecticut. One record from the breeding grounds in the Adirondacks is remarkably different, particularly in the matter of time. The records from migrating birds vary from 3/5 second to 2 seconds, but the record from the breeding grounds is 4 3/5 seconds. This record is also remarkable in its rhythm, containing groups of three notes each that, in their time arrangement, suggest the ‘peabody’ notes of the song of the white-throated sparrow. The song, which is all on one pitch, might be written Teee teelelee te te teee teee teelelee teelelee teelelee tee. With only this one record of the summer song, I cannot determine whether it is typical of the breeding songs of this species or is unusual.”

Gerald H. Thayer wrote to Dr. Chapman (1907):

In a grouping based on songs, the Bay-breast should stand in a quintette with the Blackburnian, the Black-poll the Black and White and the Cape May. These five heard singing together in the same trees, as I have heard them on the Hudson River, make ‘confusion worse than death’ for any bird-student hut the most adept. But with patience and a good ear one can learn to differentiate them surely. All five are thin-voiced, “sibilant,” singers; but each has its own slight, prevailing peculiarity of tone, in addition to the differences, varied hut never wholly violated, of phrasing and accentuation. The Bay-breast’s singing, in the spring at least, is the most liquid and inarticulate of the lot, and sometimes the loudest. It varies greatly, from the bases of at least two and probably three clearly distinct main songs. In one of these, the six or more barely-separated lisping notes are all alike in volume, accentuation, tone, and speed. They are slightly louder than the Black-poll notes, and not quite so smooth in tone. Another song begins in about the same way, hut ends with three or four clearly-separated louder notes, which have a more nearly full-voiced ring. A third, uncommon, song, which I have all but surely traced to the Bay-breast, is louder throughout, and otherwise very different. It begins with about ten penetrating notes, in close-knit couplets like those of the Black and White’s shorter song, and of much the same tone, but louder; and it ends, abruptly, with a single, lower-toned, much richer note, like a fragment of Ovenbird song.

Philipp and Bowdish (1917) say: “The song is of a character quite similar to that of the Blackburnian Warbler, but slightly stronger and louder. It is delivered for long periods, with considerable frequency, and at all times of day, though less frequently toward the middle of the day. It appears that the female sings from the nest, in answer to the male, and the song is markedly weaker, being scarcely distinguishable from that of the Blackburnian Warbler. The approach of an intruder is apt to cause the female to become silent.”

Field marks: The adults of both sexes are unmistakable, with their conspicuous chestnut markings on crown, breast, and sides, black cheeks and a huffy spot on the side of the neck, in spring plumage, the females being duller in colors and with less chestnut. Fall birds might easily be mistaken for blackpolls, which they closely resemble, but adults usually have some trace of chestnut wash on the sides, less streaking above, and none below. Young birds have no trace of chestnut on the sides. The under tail coverts of the bay breasted warbler are cream-color, while those of the blackpoll are pure white.

Fall: Bay-breasted warblers are often very common on the fall migration, sometimes really abundant. That they are sometimes commoner than we realize is a result of the difficulty of distinguishing them from the blackpolls as the two are migrating through the treetops together. As a rule, however, the bay-breasted warblers are earlier migrants, passing through New England during the last half of August and the first week of September, then in company with the blackpolls for the next two weeks, after which very few of them may be seen. In my experience, the blackpolls far outnumber them in New England, being by far our commonest warbler in the fall. The fall migration route of the bay-breasted warbler is apparently a reversal of the route followed in the spring, southward west of the Alleghenies and west of or across the Gulf of Mexico to Panama and Colombia.

DISTRIBUTION

Range: Southern Canada to northwestern South America.

Breeding range: The bay-breasted warbler breeds north to northeastern British Columbia (Lower Liard Crossing); northern Alberta (Athabaska Lake near Chipwyan); casually north to southwestern Mackenzie (Wrigley); central Saskatchewan (Flotten Lake); central Manitoba (Berens Island, Lake Winnipeg, and possibly Oxford House); central Ontario (Gorman Creek, Patricia district; Lac Seul, Lake Nipigon, and Moose Factory); and southern Quebec (Mistassini Post, Piasti, and Natashquan); casual north to Hamilton Inlet, Labrador. East to southeastern Quebec (Natashquan); west-central Newfoundland (Grand Lake); and Nova Scotia (Baddeck, Pictou, and Halifax). South to Nova Scotia (Halifax); southern Maine (Ellsworth and Thomaston); central and southwestern New Hampshire (Tamworth, Webster, and Mount Monadnock); northern New York (Adirondack Mountains); southern Ontario (Southmag and French River); northern Michigan, rarely (Sugar Island, St. Mary’s River, and Isle Royale); northern Minnesota (Clear Lake and Itasca Park; possibly Elk River); southwestern Ontario (Off Lake, Rainy River district); southern Manitoba (Indian Bay, Lake of the Woods, and Aweme); central Saskatchewan (Flotten Lake) ; central Alberta (Glenevis, Faust, and Sturgeon Lake); and central eastern British Columbia (Charlie Lake). West to northeastern British Columbia (Charlie Lake and Lower Liard Crossing; possibly Indian Point Lake and Tatana take).

Winter range: In winter the bay-breasted warbler is found north to central Panama (Canal Zone); the coastal region of Colombia (Santa Marta region); and Venezuela (Rancho Grande and Tortuga Island). South to northern Venezuela (Tortuga Island, Mérida, and La Uraca) ; and west central Colombia (Valvidia). West to western Colombia (Valvidia and Rio Frio); and eastern Panamá (Cana and Canal Zone).

Migration: Late dates of departure from the winter home are: Colombia: Malena, March 10. Panamá:Toro Point, April 27.

Early dates of spring arrival are: Mexico: Gómez Farias, Tamaulipas, April 2. Florida: Pensacola, April 23. Alabama: Sand Mountain, April 20. Georgia: Roswell, April 21. North Carolina: Piney Creek, April 24. Virginia: Lynchburg, May 3. West Virginia: Wheeling, May 2. District of Columbia: Washington, May 2. Pennsylvania: Philadelphia, May 2. New York: Ithaca, May 1. Massachusetts: Amherst, May 7. Vermont: St. Johnsbury, May 5. Maine: Lewiston, May 10. Quebec: Montreal, May 18. New Brunswick: Scotch Lake, May 10. Nova Scotia: Yarmouth, May 21. Louisiana: Thibodaux, April 12. Mississippi: Deer Island, April 19. Arkansas: Monticello, April 24. Tennessee: Greenbrier, April 10 (specimen). Kentucky: Bowling Green, April 29. Indiana: Bloomington, April 29. Ohio: Oberlin, April ’28. Michigan: Ann Arbor, May 3. Missouri: St. Louis, May 1. lowa: Giard, May 7. Wisconsin: Madison, May 3. Minnesota: St. Paul, May 4. Texas: Olmito, April 23. Kansas: Topeka, May 8. Nebraska: Greeley, May 3. South Dakota: Yankton, May 10. North Dakota: Fargo, May 9. Manitoba: Margaret, May 13. Saskatchewan: Indian Head, May 10.

Late dates of spring departure of transients are: Florida: Pensacola, May 13. Alabama: Long Island, May 22. Georgia: Athens, May 13. South Carolina: Clemson (College), May 16. North Carolina: Asheville, May 19. Virginia: Charlottesville, May 28. West Virginia: Morgantown, May 22. District of Columbia: Washington, June 5. Pennsylvania: Laanna, June 7. New York: Brooklyn, June 3. Massachusetts: Northampton, June 9. Louisiana: New Iberia, May 15. Mississippi: May 16. Arkansas: Rogers, May 27. Tennessee: Nashville, May 24. Kentucky: Danville, May 19~ Illinois: Chicago, June 5. Indiana: Notre Dame, June 4. Michigan: Ann Arbor, June 6. Ohio: Toledo, June 5. Missouri: St. Louis, June 2. Iowa: Sioux City, June 4. Wisconsin: Berlin, June 3. Texas: Laguna Vista, May 15. Oklahoma: Kenton, June 4. Nebraska: Hastings, May 25.

Early dates of fall arrival are: Minnesota: Minneapolis, August 21. Wisconsin: New London, August 15. Michigan: McMillan, August 6. Ohio: Toledo, August 6. Indiana: Dune Park, August 20. Illinois: Glen Ellyn, August 13. Kentucky: Bardstown, September 15. Tennessee: Roan Mountain, September 23. Mississippi: Bay St. Louis, September 23. Massachusetts: Harvard, September 5. New York: Rhinebeck, August 11. Pennsylvania: Pittsburgh, August 20. District of Columbia: Washington, August 17. West Virginia: Bluefield, August 29. Virginia: Lexington, September 19. North Carolina: Mount Mitchell, September 12. Georgia: Young Harris, September 29. Alabama: Birmingham, September 13: Florida: Pensacola, October 1. Panama: Cocoplum, October 24. Colombia: Novita, September 20.

Late dates of fall departure are: Manitoba: Aweme, September 26. Minnesota: St. Paul, September 29. Wisconsin: Racine, October 8. lowa: Lamont, October 2. Michigan: Detroit, October 19. Ontario: Point Pelee, October 15. Ohio: Youngstown, October 21. Indiana: Indianapolis, October 20. Illinois: Olney, October 20. Kentucky: Danville, October 20. Tennessee: Memphis, October 28. Mississippi: Saucier, October 24. Louisiana: New Orleans, October 11. New Brunswick: Grand Manan, September 16. Quebec: Montreal, October 12. Maine: Avon, September 17. Vermont: Wells River, October 13. Massachusetts: Taunton, October 8. New York: Geneva, October 12. Pennsylvania: Jeffersonville, October 20. District of Columbia: Washington, November 6. Virginia: Lawrenceville, October 12. North Carolina: Asheville, October 19. South Carolina: Mount Pleasant, October 18. Georgia: Athens, November 15. Alabama: Birmingham, October 25. Florida: Pensacola, October 27.

Casual records: A bay-breasted warbler was collected at Big Sandy, Mont., on May 24, 1903; and one was carefully observed in a bird bath at Fort Morgan, Cob., on May 19, 1933. A juvenile was shot at Narssaq, near Godthaab, Greenland, on October 15, 1898. A specimen has been taken in Bermuda.

Egg dates: Maine: 8 records, June 3 to 16; 5 records, June 10 to 15.

New Hampshire: 9 records, June 12 to 28; 5 records, June 13 to 18.

New Brunswick: 52 records, June 5 to July 2; 30 records, June 17 to 25, indicating the height of the season (Harris).