Part 76

The nest, which was found by watching the female, was built at a height of about thirty feet above the ground, on the horizontal branch of a black spruce, some six feet out from the main stem. Its bottom rested securely near the base of a short, stout twig. Above and on every side masses of dark spruce foliage, rendered still denser by a draping of Usnea (which covered the entire tree profusely), hid the nest so perfectly that not a vestige of it could be seen from any direction. This nest is composed outwardly of fine twigs, among which some of the surrounding Usnea is entangled and interwoven. The lining is of horse hair, fine, dry grasses, and a few of the black rootlets used by D. maculosa. The whole structure is light and airy in appearance, and resembles rather closely the nest of the Chipping Sparrow.

The highest nest of which I can find any record is one reported by Dr. C. Hart Merriam (1885), found by A. J. Dayan in a grove of large white pines (Pinus strobus), in Lewis County, N. Y. It was saddled on a horizontal limb of one of the pines, about 84 feet from the ground and about 10 feet out from the trunk. "The nest is large, substantial, and very compact. It consists almost entirely of a thick and densely woven mat of the soft down of the cattail (Typha latifolia), with seeds attached, and is lined with fine lichens, horse hair, and a piece of white thread. On the outside is an irregular covering of small twigs and rootlets, with here and there a stem of moss or a bit of lichen."

The lowest nests that I have heard of are recorded in Frederic H. Kennard's notes from Maine; one was only 5-1/2 feet up and the other 9 feet from the ground in small spruces. Mrs. Nice (1932) found a nest near her mother's home in Pelham, Mass., that was "18 feet from the ground near the top of a cedar among comparatively open, young growth, 40 yards south of the house and 150 yards to the east of the great pines and hemlocks where the male habitually sang." The only nest of this warbler that I have ever seen was found by watching the female building it, on June 16, 1913, on an island in Lake Winnipegosis, Manitoba; it was only about 10 feet from the ground, near the end of a drooping branch of a large black spruce that stood on the edge of some coniferous woods next to an open swale. The nest, shaded from above, was partly concealed from below by dense foliage and was, apparently, well made of soft fibers, deeply cupped, and lined with some dark material and a little willow cotton. I was not able to visit the island again.

In New York State and in Pennsylvania, the nests of the Blackburnian warbler are almost invariably placed in hemlocks. All of the four nests recorded by T. E. McMullen (MS.) from the Pocono Mountains, Pa., were in hemlocks. And Todd (1940) states that with one exception all the nests found by R. B. Simpson, of Warren, Pa., were in hemlocks, "at elevations varying from twenty to fifty feet. The exceptional nest was in a large chestnut, sixty feet from the ground."

Dr. Roberts (1936) mentions a Minnesota nest "situated in an arbor vitae tree, directly over the entrance to a cabin," and one "placed in a small spruce, close to the trunk, about 2 feet from the top of the tree and about 20 feet from the ground." Another was found in "a jack-pine tree, 20 feet from the ground, 6 feet from the trunk, resting in a tangle of small branches, and concealed by a closely overhanging branch."

Eggs.--The Blackburnian warbler lays normally 4 or 5 eggs, usually 4; in a series of 14 sets there are only 3 sets of 5. They are ovate to short ovate and slightly glossy. The ground color is snowy white or very pale greenish white, and is handsomely spotted and blotched with "auburn," "bay," "argus brown," "Mars brown," or "mummy brown," with undertones of "brownish drab," or "light vinaceous-drab." On some eggs the drab marks are the most prevalent, with fewer but more prominent spots or blotches of dark brown shades, such as "Mars brown" and "mummy brown." Others have spots of "auburn" and "bay" so concentrated that they form a solid band around the large end. In addition a few small scrawls of brownish black are often found. Generally speaking the markings tend to form a wreath, but some eggs are spotted more or less evenly all over the surface. The measurements of 50 eggs average 17.2 by 12.8 millimeters; the eggs showing the four extremes measure =18.0= by 13.6, 17.0 by =13.7=, =15.6= by 12.5, and 17.1 by =12.0= millimeters (Harris).

Young.--We have no information on incubation and very little on the care of the young. The male has been seen to go onto the nest, and evidently shares occasionally in the duty of incubation. Both parents help in feeding the young, as noted by Mrs. Nice (1932) at the nest she was watching. When Mrs. Nice's daughter climbed a tree near the nest, the female "assumed a peculiar attitude, her tail outspread and dropped at right angles to her body, her wings flipping rapidly and occasionally held stiffly up or down. The excitement caused the young to jump out on the ground where they could not be found."

Plumages.--Dr. Dwight (1900) calls the natal down sepia-brown, and in speaking of the males, describes the juvenal plumage as "above, dark sepia-brown obscurely streaked on the back with clove-brown. Wings and tail clove-brown edged with olive-buff, the tertiaries and coverts with white forming two wing bands at tips of greater and median coverts; the outer three rectrices largely white. Below, white, washed with wood brown or buff on breast and sides, spotted, except on chin, abdomen and crissum, with dull sepia. Superciliary stripe cream-buff, spot on upper and under eyelid white; lores and auriculars dusky."

A partial postjuvenal molt begins early in August, involving the contour plumage and the wing coverts but not the rest of the wings or the tail. This produces the first winter plumage, which he describes as "above, deep yellowish olive-gray, flecked on the crown and streaked on the back with black; obscure median crown stripe straw-yellow; rump and upper tail coverts black, edged with olive-gray. Wing coverts clove-brown edged with olive-gray and tipped with white forming two broad wing bands. Below, straw-yellow brightening to orange-tinged lemon on the throat, fading to buffy white on the crissum and narrowly streaked on the sides with black veiled by yellow edgings. Superciliary stripe and post-auricular region lemon-yellow orange-tinged. Auriculars, rictal streak and transocular stripe olive-gray mixed with black. Suborbital spot yellowish white."

He says that the first nuptial plumage is "acquired by a partial prenuptial moult which involves most of the body plumage (except posteriorly), the wing coverts and sometimes the tertiaries but not the rest of the wings nor the tail. The full orange and black plumage is assumed, young and old becoming practically indistinguishable, the orange throat equally intense in both, the wings and tail usually browner in the young bird and the primary coverts a key to age."

The adult winter plumage is acquired by a complete postnuptial molt in July, and "differs little from the first winter dress, but the yellow more distinctly orange, the transocular and rictal streaks, the crown and auriculars distinctly black, veiled with orange tips, the streaking below heavier and broader, the wings and tail blacker and the edgings grayer." The adult nuptial plumage is acquired as in the young bird; this molt evidently begins in February, while the birds are in their winter quarters, and is usually finished before they reach their summer homes.

Of the females, Dr. Dwight says:

The plumages and moults correspond to those of the male. In juvenal plumage the wing edgings are usually duller, the first winter plumage being similar to that of the male but browner, the yellow tints nearly lost and the streakings obscure and grayish. The first nuptial plumage, assumed by a more or less limited prenuptial moult, is grayer above and paler below, except on the chin and throat where new pale orange feathers contrast with the worn and faded ones of the breast. The adult winter plumage is practically the same as the male first winter, the auriculars and transocular stripe usually duller. The adult nuptial plumage is brighter below than the first nuptial and with more spotting on the crown, but the black head and bright orange throat of the male are never acquired.

Food.--The Blackburnian warbler is mainly insectivorous like other wood warblers, feeding almost entirely on the forest pests that are so injurious to the trees. F. H. King (1883), writing of its food in Wisconsin, says: "Of nine specimens examined, four had eaten nine small beetles; five, nineteen caterpillars; one, ants; and one, small winged insect. In the stomachs of three examined collectively, were found four caterpillars, four ants, one dipterous insect .09 of an inch long, one medium sized heteropterous insect, four large crane-flies, and one ichneumon-fly (?). Another bird had in its stomach one heteropterous insect (Tingis), nine small caterpillars, two leaf-beetles, and two large crane-flies."

Ora W. Knight (1908) writes: "In general I have found large quantities of the wing cases and harder body portions of beetles in the stomachs of such Blackburnian Warblers as I have dissected, also unidentifiable grubs, worms, larvae of various lepidopterous insects and similar material. As a rule they feed by passing from limb to limb and examining the foliage and limbs of trees, more seldom catching anything in the air."

R. W. Sheppard (1939), of Niagara Falls, Ontario, observed a male Blackburnian warbler in his garden for several days, November 5 to 11, 1938, that appeared to be traveling with two chickadees, among some willow trees. "An examination of the row of low willow trees which appeared to be so attractive to this particular warbler, revealed the presence of numbers of active aphids and innumerable newly laid aphis eggs, and it is probable that these insects and their eggs provided the major incentive for the repeated and prolonged visits of this very late migrant."

Henry D. Minot (1877) observed "a pair feeding upon ivy berries" on April 21, when insects were not yet common in Massachusetts.

Behavior.--William Brewster (1938) describes what he thought was the unique behavior of a female Blackburnian warbler at its nest, although a similar habit has been observed in other wood warblers. Even though the eggs "were perfectly fresh the female sat so closely that thumping and shaking the tree (a slender one) failed to start her, and when Watrous climbed it he nearly touched her before she slipped off. She then dropped like a stone to the ground over which she crawled and tumbled and fluttered with widespread tail and quivering wings much like a Water Thrush or Oven Bird and evidently with the hope of leading us away from the nest."

The Blackburnian is pre-eminently a forest warbler and a tree-top bird. On migrations it frequents the tops of the trees in the deciduous forests, often in company with other wood warblers; and on its breeding grounds in the coniferous forests the male loves to perch on the topmost tip of some tall spruce and sing for long periods, his fiery breast gleaming in the sunlight. As his mate is probably sitting on her nest not far away, his serenity may be disturbed by the appearance of a rival; but the intruder in his territory is promptly driven away and he resumes his singing.

Voice.--Aretas A. Saunders has sent me the following study: "The song of the Blackburnian warbler is one that is usually of two distinct parts, the first a series of notes or 2-note phrases all on one pitch, and the second a faster series, or a trill, on a different pitch. It is very high in pitch, with a thin, wiry quality, rather unmusical, and not loud but penetrating.

"Of my 34 records, 25 have the second part higher in pitch than the first, while in the other 9 it is lower. I do not think, however, that this means that the higher ending is commoner, for there is reason to think that the difference is geographical. Of 11 records of migrating birds in Connecticut, 10 end in the higher pitch. Of 15 records from breeding birds in the Adirondacks, 13 end in the higher pitch; but of 8 records of breeding birds in Allegany State Park in western New York, only 2 end in the higher pitch, and 6 in the lower.

"In 20 of the records the first part of the song is of 2-note phrases, but the remainder is of single repeated notes. In 6 records, ending in a higher pitch, the final trill slurs upward in pitch, suggesting the ending of a typical parula song in form. In 10 of the records the second part is much shorter than the first.

"Songs vary from 1-2/5 to 2-2/5 seconds, averaging a little longer than those of other species of this genus. The number of notes in songs, excepting those with trills, varies from 7 to 25, and averages 14. Pitch varies from D´´´´ to F´´´´, one and a half tones more than an octave. It ranks with the black-polled and bay-breasted warblers in the very high pitch of its upper notes but shows more variation in pitch than either.

"The song of this bird ceases earlier in summer than most others. In 14 summers in Allegany Park, the average date of the last song was July 12, the earliest July 4, 1929, and the latest July 22, 1935. I have never heard singing in late summer after the molt."

Francis H. Allen sends me his impressions as follows: "Like so many of our warblers, the Blackburnian has two song-forms, but both are subject to great individual variation. An extremely high note is almost an invariable characteristic. In one form it is the closing note, and in the other it ends each repeated phrase of a succession that constitutes the main part of the song. The first song resembles that of the parula, but ends with this high note, while the main part is less buzzy and more what I might call pebbly in character. The second I have been accustomed to call the chickawee song because of the repeated phrase which suggests those syllables. At Sherburne, Vt., in June, 1907, I found the Blackburnians singing a song that I rendered as ch[)i]-ee ch[)i]-ee ch[)i]-ee ch[)i]-ee chip. Another rendering of the same or a similar song, recorded at Jaffrey, N. H., May 30, 1910, was serwée serwée serwée serwée serwíp, with the emphasis on the wip. At New London, N. H., in June, 1931, where this was perhaps the commonest of the warblers, I was particularly impressed by the variability of both the songs. In some, the very high and attenuated notes were so short that for some time I failed to recognize their source. One bird sang chiddle chiddle chiddle chick-a chick-a cheet. At Hog Island in Muscongus Bay, Maine, in June, 1936, I heard a song of which only a sweet weet weet weet weet carried to a distance, but of which, heard near at hand, the end was found to be a short, confused succession of high-pitched, dry notes concluding with a very high, short note. This was, I think, the most pleasing performance I have ever heard from this species."

Mrs. Nice (1932) mentions three different songs; the commonest and shortest, like the parula's in form, lasts for one second and is given at intervals of 7-1/2 to 10 seconds; the rarest and longest lasts for two seconds and is given at intervals of 10 or 14 seconds.

A. D. DuBois tells me that the Blackburnian warbler "has a song not unlike that of the dickcissel in its general form, although much subdued in volume." Gerald Thayer wrote to Dr. Chapman (1907) of two or more different songs of this warbler, and says:

Its voice is thin, but, unlike the Parula's, exquisitely smooth, in all the many variations of its two (or more) main songs. * * * Even the tone quality is not quite constant, for though it never, in my experience, varies toward huskiness, it does occasionally range toward full-voiced richness. Thus I have heard a Blackburnian that began his otherwise normal song with two or three clear notes much like those of the most full and smooth-voiced performance of the American Redstart's, and another that began so much like a Nashville that I had to hear him several times, near by, to be convinced that there was not a Nashville chiming in. Sometimes, again, tone and delivery are varied toward excessive languidness; and sometimes, contrariwise, toward sharp, wiry "thinness."