“Songs vary from 12⁄5 to 22⁄5 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 chĭ-ee chĭ-ee chĭ-ee chĭ-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 71⁄2 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.”
Enemies.—Dr. Friedmann (1929) calls the Blackburnian warbler “a very uncommon victim of the Cowbird.” Dr. Merriam (1885) records a nest of this warbler that was 84 feet from the ground, containing four warbler’s eggs and one of the cowbird, of which Friedmann remarks: “This is probably the altitude record for a Cowbird’s egg, bettering by some twenty feet my highest record at Ithaca, a Cowbird’s egg in a nest of a Pine Warbler about sixty feet up.”
Harold S. Peters (1936) records two species of lice, Menacanthus chrysophaeum (Kellogg) and Ricinus pallens (Kellogg), and one mite, Proctophyllodes sp., as external parasites of this warbler.
Field marks.—The adult male Blackburnian warbler in spring plumage is unmistakable, with its black upper parts, large white patch in the wings, orange stripe in center of the crown and another over the eye, and, especially, the flaming orange throat and breast. The female in the spring and the male in the fall are similarly marked, but the colors are much duller. The colors of young birds in the fall are even duller, and the back is brownish, but the white outer web of the basal half of the outer tail feather should indicate the species.
Fall.—Early in August, young and old birds begin to gather into flocks preparing to migrate, and before the end of that month most of them have left their breeding grounds. All through August and most of September, we may see them drifting through our deciduous woods in mixed flocks with other species of warblers. These migrating flocks are generally so high up in the tree tops and are so active in their movements that it is not easy to identify them in their dull winter plumages.