Chapter M: G. Vaiden writes to me that he found a nest near Belzoni, Miss., in a (5)

The first published report of the nesting of the Cape May warbler was perhaps based on an error in identification. Montague Chamberlain (1885) reported that his friend James W. Banks found a nest apparently "just outside the city limits" of Saint John, New Brunswick; he states that it "was hid among a cluster of low cedars growing in an exposed position, on a rather open hill-side, near a gentleman's residence, and within a stone's throw of a much frequented lane. The nest was placed less than three feet from the ground and within six inches of the tips of the branches." The location of this nest, as will be seen from the accounts that follow, was entirely different from that of the many nests found since; both nest and eggs were said to resemble somewhat those of the magnolia warbler; no male Cape May warbler was seen or heard, and the bird Banks reports having shot from the nest may have been wrongly identified, since the females of the two species are somewhat alike. Referring to this account, James Bond (1937) remarks: "It would be wise to regard the 'classical' nest taken near Saint John, New Brunswick, by Banks as that of a Magnolia Warbler, as is indicated not only by its situation but by its construction, for the nest of the Cape May Warbler is a decidedly more bulky affair. I mention this since recent books still perpetuate this undoubted error, ignoring the information that has been gleaned during the past twenty years."

Probably the first undoubted nest of the Cape May warbler was found on an island in Lake Edward, Quebec, on June 7, 1916, by Dr. H. F. Merriam, who published an interesting account of it (1917). He watched the building of the nest for some days before the nest was taken on the eighteenth. The female was seen carrying nesting material into the thick top of a spruce about 40 feet from the ground in a rather open part of the woods, consisting for the most part of spruce and balsam of moderate size interspersed with large white and yellow birches.

The female was not at all timid and apparently gathered most of her nesting material at two places, both within sixty feet of the nest tree. * * * While searching in the low growth she was absorbed in manner, giving only occasionally a sharp chip. In going to the nest her actions were more rapid and she chipped more frequently, generally alighting ten to twenty feet below the nest and working her way up from limb to limb on the outside of the tree. * * * The male was not seen to carry any nest material but seemed to be generally in the immediate neighborhood. At times he accompanied the female part way to or from the nest and sometimes remained near her in the low spruces. * * *

The nest was placed about six feet from the top of the tree on a short branch nine inches from the trunk and an equal distance from the tip. From the ground it could not be seen even with field glasses. From a few feet below the nest was apparently a green ball of moss. Closer examination, however, showed it to be a neatly cupped nest resting on the branch and short twigs. To these it was not securely tied and was lifted intact from its position without difficulty.

The exterior of the nest was of green Sphagnum moss, interwoven with vine stems, and a very few twigs, bound lightly with plant down, small wads of which appeared here and there over the moss. The body of the nest consisted of fine grass stems. Within this was a lining of white hairs apparently from the rabbit, one small partridge feather and a few fine black rootlets. The nest was bulky but very neatly and fairly compactly put together. At the rim one side was very smoothly finished. This was probably the entrance side toward the tree trunk. It was an unusual and beautiful nest.

Its dimensions were: outside, 4 inches wide by 2-1/4 deep; inside, 1-3/4 inches wide by 1 inch deep.

Two years later, Philipp and Bowdish (1919) found four nests in northern New Brunswick. "They were in rather high spruce trees, within two or three feet of the extreme top, usually as near the top as suitable site and cover could be secured. All were built in very thick foliage, against the main stem of the tree, resting lightly on twigs and foliage, but fairly secured thereto by webs, and were entirely invisible from the ground, in every case." The nests were from 35 to 40 feet above the ground, and were not substantially different in size and construction from that described by Dr. Merriam. They add that the thick lining of hair, feathers, and a little fur, all smoothly felted, serves to distinguish the nests from those of the black-poll and myrtle warblers, and note that the nest tree is usually "fairly openly situated, at least as to one side, although this is not always the case, since other pairs watched were very evidently nesting in trees where it was much more difficult to detect them."

Richard C. Harlow has sent me the data for seven nests of the Cape May warbler that he collected in Tabusintac, New Brunswick, in 1919. Two of these were 55 feet from the ground in a fir, and the others were 35, 45, 50, 55, and 60 feet up, respectively, in black spruces. All were in the very topmost shelters of the trees, and three of them were in heavy forests, the others being on the edges. In other respects they were similar to those described above. The females sat very closely until almost touched, and then dropped down to the ground.

The nest found by James Bond (MS.) on Mount Desert Island, Maine, was against the trunk of a red spruce 38 feet above ground and about 4 feet from the extreme top of the tree. In construction it was similar to those described above. In his published (1937) paper the tree was said to be a black spruce, but he now writes to me that it was a red spruce and that there were no black spruces in the immediate vicinity; these two spruces are difficult to distinguish.

Dr. Paul Harrington, of Toronto, writes to me that he found a nest of the Cape May warbler in an open spruce forest near Dorcas Bay, Bruce Peninsula, on June 12, 1934. "The tree was about 35 feet high, a typical 'church spire.' Near the top was a heavy clump, but I could see nothing that indicated a nest; when I put my hand in the heavy needles near the trunk a bird popped out and straight down. * * * I carefully groped about and eventually found the nest, built near the trunk in the uppermost clump of needles."

_Eggs._--Mr. Harlow tells me that the Cape May warbler lays from 4 to 9 eggs to a set. The larger numbers must be very rare, but 6 or 7 seem to be the commonest numbers among my records, and sets of 4 seem to be uncommon. The eggs vary in shape from ovate to short ovate and are almost lusterless. They are creamy white, richly spotted and blotched with shades of reddish brown, such as "auburn," "chestnut," "sayal brown," "bay," or "snuff brown," with an occasional scrawl of black. The undermarkings are of "fawn," "light brownish drab," "brownish drab," or "light mouse gray." The markings are more concentrated at the large end. The measurements of 50 eggs average 16.8 by 12.5 millimeters; the eggs showing the four extremes measure =18.4= by 12.3, 18.0 by =14.0=, =15.0= by 12.0, and 16.0 by =11.5= millimeters (Harris).

_Plumages._--Dr. Dwight (1900) describes the juvenal plumage, in which the sexes are alike, as "above, dark hair-brown, olive tinged on the back. Wings and tail black, edged chiefly with dull brownish olive-green, the coverts with drab and tipped with buffy white. The two outer rectrices with subterminal white spots. Below, including sides of head, mouse-gray with dusky mottling or streaking on the breast and sides; the abdomen and crissum dingy white faintly tinged with primrose-yellow."

The partial postjuvenal molt, beginning early in July, involves the contour plumage and the wing coverts, but not the rest of the wings or the tail. This produces the first winter plumage, in which the sexes begin to differentiate. Dr. Dwight describes the first winter male as "above, dull olive-green, each feather centrally clove-brown veiled with olive-gray edgings; the rump canary-yellow, the feathers basally black. Below, including sides of neck, superciliary lines and spot under eye, canary-yellow, palest on abdomen and crissum, narrowly streaked on sides of chin, on the throat, breast and sides with black which is veiled by grayish edgings; auriculars mouse-gray." The young female, he says, is "duller and browner above, and generally without yellow below, being dull white with gray streaking."

The first nuptial plumage is acquired by a partial prenuptial molt beginning in late winter, "which involves much of the body plumage but not the wings nor the tail. The black crown, the streaks on the back, the chestnut ear-patches and the streaked yellow of the throat and breast are acquired," in the male. The female in first nuptial plumage "shows a little yellow assumed by a limited prenuptial moult." Both sexes are now in nearly fully adult plumage, except for the worn juvenal wings and tail.

Adults have a complete postnuptial molt in July and probably a partial prenuptial molt, as in the young bird, though there is not enough pertinent material available to prove the latter. Dr. Dwight (1900) says that the adult winter plumage of the male is "similar to first winter plumage but the head black, the back streaked and everywhere veiled with smoke-gray edgings. Below, whitish edgings obscure the black streaks, the chestnut ear-coverts and the bright lemon-yellow areas. The wings and tail are blacker than in first winter, the back is black, either streaked or spotted, and the yellow below is deeper." Of the female, he says: "The adult winter plumage is similar to the male in first winter dress, the yellow below rather paler and with less heavy streakings."

_Food._--Throughout most of the year the Cape May warbler is insectivorous, and mainly beneficial, but for a short time on its fall migration it undoubtedly causes damage to ripe grapes by puncturing them to obtain the juice, often ruining a large percentage of the crop. Many complaints have been made and several have been published. Frank L. Burns (1915a) claimed that about 50 percent of his crop was destroyed at Berwyn, Pa., and says: "I believe that grape juice was the principal food of the Cape May Warbler during its lengthy visit in this neighborhood. It was present in countless numbers at Berwyn and vicinity as far as a mile south of the village, apparently by far the most abundant species for a period; the complaints of the the 'little striped yellow bird' were many, and so far as I am able to learn, all unbagged grapes were ruined; the loss must have been many tons worth several hundred dollars." He sent ten stomachs to the Biological Survey for analysis and received the following reply:

Hymenoptera constituted on an average 57.5 percent of the contents of the stomachs. A third perhaps of this material was parasitic Hymenoptera and their destruction counts against the bird. The others were ants and small bees and are of neutral importance except perhaps the ants which may be injurious. Diptera made up 16.7 percent of the stomach contents and again a large proportion of them were parasitic species. Lepidoptera (small moths) constitute 16.7 per cent, beetles 7.8 percent and the remainder was made up of Hemiptera, spiders and miscellaneous insects. Except for the spiders the food was entirely composed of insects, and a large proportion of useful species were taken and no decidedly injurious ones. I should say that these Cape May Warblers did very little to pay for the destruction of grapes.

McAtee (1904), after investigating the damage done on grapes by this and the Tennessee warbler in Indiana, published the following report on the contents of a single stomach of a Cape May warbler:

8 _Typlocyba comes_, an especial pest of the grape, "an exceedingly abundant and destructive" jassid; 3 _Aphodius inquinatus_ and one Carabid, kinds which may be considered neutral economically, but, in case of a departure from their ordinary diet, would on account of vegetarian tendencies become injurious; 1 _Drasterias_ sp. (click-beetle), 1 tortoise-beetle, 1 flea-beetle (_Haltica chalybea_), all injurious beetles, the last of which is a particular enemy of the grape, which "appears on the vine in early spring and bores into and scoops out the unopened buds, sometimes so completely as to kill the vine to the roots," and later in the season in both larval and adult stages feeds upon the foliage, and if abundant "leaves little but the larger veins"; 1 _Notoxus_ sp., a weevil, with all the undesirability characteristic of the creatures bearing that name; 2 ants, harmful, if for no other reason than harboring plant lice; and a vespoidean hymenopteron (wasp) of neutral significance. * * *

The feeding habits of the birds may, from the present knowledge, be declared practically entirely beneficial. In return it seems not too much to expect that we should without complaint furnish, for a few days in the year, the drink to wash the great numbers of our insect enemies down to their destruction; and to consider these two little fellows as among the worthiest as they are among the prettiest of our warbler friends.

Prof. Maurice Brooks (1933), speaking of this warbler in West Virginia, says:

We had at that time [1909] a small commercial vineyard, and during the first week in September, when the crop was just ripening, we were surprised to find in the vineyard swarms of Cape May Warblers. We were not long in doubt as to their purpose there, for within a week they had destroyed practically every grape we had. * * * Their method was to puncture the skin of the berry at one point, extract a little juice, and move on to the next. They would systematically work over every berry in the cluster, if undisturbed, and they soon became exceedingly tame. It is no exaggeration to say that there were hundreds of the birds in the locality.

After the birds had made one puncture, swarms of bees and wasps soon finished the work of destruction. There was no way of frightening so many birds away, and we were driven to sacking our grapes in the future. The next year, 1910, they returned in numbers again, destroying practically all unsacked clusters, and completely cleaning out the vines of our neighbors, who raised just a few grapes for their home use.

These and other warblers have been seen drinking sap from the holes dug in trees by sapsuckers, but they also obtain some insects from such borings and perhaps also from the punctured grapes, which make fine insect traps. However, the damage does not seem to be universal, and occurs only where the birds are abundant, and then for only a short time. In view of his record as an insect destroyer, the laborer may be worthy of his hire.

To the insects mentioned as food for this warbler, A. H. Howell (1932) adds small crickets, flies, leaf hoppers, termites, larvae of moths, dragonflies, and daddy-long-legs.

_Behavior._--Brewster (1938) writes:

It keeps invariably near the tops of the highest trees whence it occasionally darts out after passing insects. It has a habit of singing on the extreme pinnacle of some enormous fir or spruce, where it will often remain perfectly motionless for ten or fifteen minutes at a time; on such occasions the bird is extremely hard to find, and if shot is almost certain to lodge on some of the numerous spreading branches beneath. * * * In rainy or dark weather they came in numbers from the woods to feed among the thickets of low firs and spruces in the pastures. Here they spent much of their time hanging head downward at the extremity of the branches, often continuing in this position for nearly a minute at a time. They seemed to be picking minute insects from the under surface of the fir needles. They also resorted to a thicket of blossoming plum trees directly under our window, where we were always sure of finding several of them. There were numerous Hummingbirds here also, and these, the Cape Mays were continually chasing.

While watching a pair at their nest building, Dr. Merriam (1917) saw a female on the ground gathering material; she "was attacked by a Junco and after a chase the Junco actually caught and held her. At this commotion the male Cape May flew down and lit close by but took no active part in the argument. The Junco was apparently victor for after one more flight to her nest the female Cape May was not again seen to trespass on the Junco's territory or do any more nest building that morning." However, in his notes from West Virginia, Dr. J. J. Murray says that "this warbler is more active and restless in its feeding than any of our warblers, except possibly the myrtle; and it is also noisier and more aggressive in its attitude toward other warblers which seek to share its feeding places." Harlow also says that "the male Cape May is the tiger of the north woods in defending his territory. He attacks all birds that come close to the nest, up to the size of the olive-backed thrush, and is absolutely fearless."

_Voice._--Aretas A. Saunders sends me the following note on the song of this warbler: "I have had few opportunities to study the song of the Cape May warbler, and have only five records. These show that the song is weak, high-pitched and somewhat sibilant. The notes are mainly all on one pitch, in even rhythmic time and from eight to eleven in number. They are pitched on E´´´´ and F´´´´. Two of the songs have one or two notes, near the end, a half-tone higher in pitch than the others. The songs are from 1-3/5 to 2 seconds in length."

Francis H. Allen (MS.) heard one singing and feeding in some Norway spruce in West Roxbury, Mass., on May 10. "He had _chip_ notes very much like a familiar note of the chipping sparrow. (I have also recorded a _prssp_ like that of the black-poll warbler but fainter and sometimes doubled.) This bird had a variety of songs. The simplest one resembled the black and white warbler's song and a short simple song of the redstart, but was thinner and harder in quality than the latter. Then there were other, more elaborate songs, some divided into two parts and some into three. Two or three times he sang several times with no pauses between, making what was practically a long continuous song. The chief characteristic of the songs, I should say, was short and staccato double notes, the latter part of which were very high-pitched. These repeated several times formed the simplest of the songs. The song in three parts reminded me of that of the Tennessee warbler, but was higher pitched and not so full and loud. The bird had long periods of silence, but sang freely when he did sing."

Brewster (1938) says that "the song of this Warbler is harder--or at least sharper and more penetrating--than that of either the Bay-breast or Blackburnian. In these respects it resembles the song of _Protonotaria_ but the tone or quality is more wiry and, indeed, very close to that of _Mniotilta_."

_Field marks._--The adult male Cape May warbler should be unmistakable in his brilliant spring plumage, with his black cap, chestnut cheeks, white lesser wing coverts, and bright yellow breast conspicuously streaked with black.

The female lacks the black cap and chestnut cheeks; her breast is pale yellow streaked with pale dusky; and all her colors are duller. Young birds are much like the female, but are still duller in coloration. See descriptions of other plumages. The tail-tilting habit is quite pronounced.

_Fall._--The fall migration starts in August and is prolonged through September, or even into October or a little later. The birds are numerically more abundant in the fall because of the large families of young, but they are less conspicuous while the foliage is still on the trees and while they are clad in dull autumn and immature plumages. Deciduous woods seem to be their favorite haunts at this season. The migration route is a reversal of the spring route, the main flight being between the Mississippi and the Alleghenies.

In this area, the birds are often excessively abundant, as shown by the accounts in the preceding paragraphs under food. They are common in Florida on migration on their way to the Bahamas and West Indies. C. J. Maynard (1896) writes:

"They were very abundant at Key West in November, frequenting the gardens near the houses where they were searching among the tropical trees and shrubs for inesects. The birds were very unsuspicious, often clinging to branches which overhung the sidewalks within a few feet of the passengers. They appeared to prefer the inhabited portion of the Key, for I rarely found them in wooded districts. The majority left the island before the first of December, but a few remained all winter."

_Winter._--Maynard (1896) says: "These birds are also common on all of the northern Bahamas which I have visited, occurring in the thickets about gardens as well as in the dense scrub. I found them abundant on Inagua in February, 1888. Here they were feeding upon the juices of a large tubular flower of a peculiar species of vine, in company with the Bahama Honey Creeper and the Lyre-tailed Hummingbird."

In Cuba, according to Dr. Barbour (1923), "a few arrive from time to time during the autumn, but in February they become really common; they stay until May. They are great flower feeders and haunt aloes and the majagua tree when it is in bloom. Many may be seen about the sisal plantations near Matanzas and in gardens where agaves blossom."

Wetmore and Swales (1931) write: "Though the Cape May warbler is found through the Greater Antilles Hispaniola appears to be the winter metropolis of the species as the birds are found throughout the island often in considerable numbers. In fact their abundance in some localities is almost bewildering to one accustomed to their rarity as migrants in the eastern United States."

DISTRIBUTION

_Range._--Eastern North America and the West Indies.

_Breeding range._--The Cape May warbler breeds =north= to northeastern Alberta (Chipewyan); possibly southwestern Mackenzie (Simpson); northern Saskatchewan (north shore of Lake Athabaska near Fair Point); central Ontario (Moose Factory); and southern Quebec (Lake Abitibi, Lake Edward, and Anticosti Island). =East= to eastern Quebec (Anticosti Island and Grand Grève); New Brunswick (Tabusintac and Saint John); and Nova Scotia (Wolfville and Stewiacke). =South= to Nova Scotia (Stewiacke); southern Maine (Ship Harbor, Mount Desert Island; Hog Island, Muscongus Bay; Pemaquid Point; and Auburn); northern New Hampshire (Lake Umbagog); south-central Vermont (Mount Killington); northern New York (North Elba); southern Ontario (Dorcas Bay and Biscotasing); northern Michigan (Newberry and Camp Cusino); northern Wisconsin (Kelley Brook and Harbster); rarely northeastern Minnesota (Gabro Lake); southwestern Ontario (Lac Seul); and central Alberta (Lesser Slave Lake and Sturgeon Lake). =West= to west-central and northeastern Alberta (Sturgeon Lake and Chipewyan). The Cape May warbler probably breeds in northern Manitoba since it is a regular, though not abundant, migrant in the southern part of the province.

_Winter range._--The winter home of the Cape May warbler is in the West Indies =north= to the Bahamas (Nassau and Watling Island), =east= and =south= to St. Lucia, and =west= to Jamaica and western Cuba (Isle of Pines and Habana). It has also been found on the island of Roatán, Honduras. It was found in Quintana Roo not far from Xcopén on March 13 which is the second record for Mexico; the other is simply "Yucatán."

_Migration._--Late dates of spring departure from the winter home are: Virgin Islands--St. Croix, April 25. Puerto Rico--Mayagüez, April 8. Haiti--Île à Vache, April 30. Cuba--Habana, May 4. Bahamas--Nassau, May 15.

Early dates of spring arrival are: Florida--Key West, March 6. Georgia--Macon, April 7. South Carolina--Chester, April 15. North Carolina--Greensboro, April 13. District of Columbia--Washington, April 19. Pennsylvania--Carlisle, April 30. New York--Geneva, April 30. Massachusetts--Amherst, May 4. Vermont--Clarendon, May 7. Maine--Auburn, May 4. New Brunswick--Scotch Lake, May 8. Nova Scotia--Pictou, May 11. Quebec--Montreal, May 14. Tennessee--Nashville, April 16. Kentucky--Russellville, April 27. Indiana--Bloomington, April 22. Ohio--Oberlin, April 27. Michigan--Ann Arbor, April 27. Ontario--London, May 1; Moose Factory, May 28. Iowa--Davenport, May 2. Wisconsin--Racine, May 2. Minnesota--St. Paul, May 2. South Dakota--Sioux Falls, May 12. North Dakota--Argusville, May 11. Manitoba--Aweme, May 10. Saskatchewan--Indian Head, May 16. Alberta--Medicine Hat, May 17.

Some late dates of spring departure of transients are: Florida--Warrington, May 18. Alabama--Anniston, May 7. Georgia--Round Oak, May 15. South Carolina--Clemson (College), May 17. North Carolina--Arden, May 19. Virginia--Naruna, May 29. District of Columbia, Washington, May 30. Pennsylvania--Doylestown, May 26. New York--Watertown, June 1. Massachusetts--Northampton, June 6. Tennessee--Nashville, May 15. Kentucky--Bowling Green, May 10. Illinois--Chicago, June 3. Indiana--Lafayette, May 31. Ohio--Austinburg June 2. Michigan--Sault Ste. Marie, June 7. Ontario--Ottawa, June 7. Minnesota--Minneapolis, June 1. South Dakota--Sisseton, June 3. North Dakota--Grafton, June 5. Manitoba--Aweme, June 1.

Late dates of fall departure are: Alberta--Camrose, August 26. Saskatchewan--Eastend, August 29. Manitoba--Winnipeg, October 7. North Dakota--Fargo, October 3 (bird banded). Wisconsin--Racine, October 16. Iowa--Iowa City, November 27. Michigan--Detroit, October 16. Ontario--Point Pelee, October 5. Ohio--Cleveland, November 2. Indiana--Waterloo, October 15. Illinois--Rantoul, October 23. Kentucky--Bowling Green, October 15. New Brunswick--Scotch Lake, September 28. Massachusetts--Belmont, November 25. New York--Hewlett, November 15. Pennsylvania--West Chester, October 31. District of Columbia--Washington, November 26. Virginia--Sweet Briar, November 29. North Carolina, Raleigh, November 1. South Carolina--Mount Pleasant, November 3. Georgia--St. Marys, October 31. Florida--Lemon City, November 25.

The Cape May warbler sometimes lingers very late in fall migration. It has been found on Long Island at Hewlett as late as December 4; at Harrisburg, Pa., one was trapped and banded on December 5; it has twice been collected at Washington, D. C., on December 16; one was found at Bethany, W. Va., on December 7; one seen at Brownsville, Tex., on December 22; and reported in December at Key West, Fla.

Early dates of fall arrival are: Manitoba--Winnipeg, August 20. North Dakota--Fargo, September 18. Minnesota--Minneapolis, August 25. Wisconsin--Green Bay, August 1. Illinois--Chicago, August 19. Ontario--Cobalt, August 12. Michigan--Whitefish Point, August 5. Ohio--Toledo, August 14. New Hampshire--Pequaket, August 24. Vermont--Wells River, August 4. Massachusetts--Harvard, August 30. New York--Rhinebeck, August 3. Pennsylvania--Pittsburgh, August 28. District of Columbia--Washington--August 4. Virginia--Charlottesville, September 4. North Carolina--Weaverville, September 15. South Carolina--Charleston, September 13. Georgia--Savannah, September 23. Florida--Sombrero Key, September 17. Bahamas--Cay Lobos, October 20. Cuba--Santiago de las Vegas, September 20. Dominican Republic--Sánchez, October 23. Puerto Rico--Faro de Cabo Rojo, September 17.

_Banding._--The one banding recovery available is especially interesting as it indicates a peculiar migration. A Cape May warbler banded at Elmhurst, Long Island, N. Y., on September 12, 1937, was caught by a cat October 15, 1937 at Cleveland, Tenn.

_Casual records._--In British Columbia one was collected June 17, 1938, at Charlie Lake. In California one was collected at Potholes on the Colorado River, September 23, 1924. A specimen labeled "Arizona" taken before 1876 is in the museum in Paris. The Cape May warbler has been once observed in Bermuda, April 3, 1909.

_Egg dates._--Maine: 2 records, June 6 to 15.

New Brunswick: 68 records, June 10 to 29; 43 records, June 12 to 20; indicating the height of the season.

DENDROICA CAERULESCENS CAERULESCENS (Gmelin)

NORTHERN BLACK-THROATED BLUE WARBLER

PLATES 29, 30

HABITS

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 breeding 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 black-throated 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, Ind., 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 warblers "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 black-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 Umbagog Lake, Maine, "the local population was chiefly concentrated wherever there were extensive patches of yew (_Taxus canadensis_)." 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 spruce, 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 minutes 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, claiming 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 he wrote an interesting account of his hunt for it in "Locusts and Wild Honey." 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 agony 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 (_Kalmia 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, 3-1/2 inches; inside, 2 inches; depth, outside, 2-1/4 inches; inside, 1-1/8 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 birch-bark, 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 Burtch (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 porcupine (even large enough for their barbs to be visible to the naked eye). This sort 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, 3-1/2 inches, inside, 2-1/4 inches; height, outside, 5 inches; depth, inside, 1-1/2 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 (_Taxus canadensis_). Apparently, the favorite nesting sites of the black-throated blue warbler are in the broadleaf evergreens, mountain-laurels 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 twenty-four 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," "chestnut-brown," "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-long-legs, 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 36-1/2 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 butterflies 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 buffy 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 (pl. 30) the female incubating and both sexes feeding the young at very short range without any special concealment; 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 foliage 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 Warblers 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 1-1/5 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 longer.

"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 whistle, 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 Allegany State Park is July 21. The earliest is July 14, 1927 and 1940, and the latest July 29, 1931. The song is rarely revived in August, after the molt."

Francis H. Allen (MS.) writes the two common songs as "_quee quee quee-e-e´_" and "_que-que-que-que quee-ee´_," and says further, "in June 1907, I heard a bird in Shelburne, Vt., that sang persistently a short song like _k[=u] quee-e-e´_ besides singing occasionally one of the ordinary songs. In May, 1910, at Jaffrey, N. H., I heard a bird sing over and over _qui-qui-qui-qui-qui-qui-qui-qui-quee´_, but most of the birds of the region seemed to sing _zee zee 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 male 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 near the 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: