Albert R. Brand (1938), in his mechanically recorded songs of warblers, placed the black-and-white’s song as the fourth highest in pitch in his last of 16 species, the black-poll, blue-winged, and the Blackburnian being higher. He gives the approximate mean (vibrations per second) of the black and white as 6,900 and of the blackpool as 8,900.
Aretas A. Saunders (MS.) says: “The pitch of the songs varies, according to my records, from B‴ to E‴′, a range of three and a half tones more than an octave. A single song, however, does not vary more than three and a half tones.”
A second song, not heard, I think, until the bird has been on its breeding ground for some time, is rather more pleasing, less monotonous, than the first. It is longer, somewhat faster, more lively, and is modulated in pitch. Francis H. Allen (MS.) speaks of it thus: “Later in the season a more elaborate song is very commonly heard. I have been accustomed to syllabify it as weesy, weesy, weesy, weesy, woosy, woosy, weesy, weesy. The notes indicated by woosy really differ from the others only by being pitched lower.”
Occasionally we hear aberrant songs which prove puzzling until we can see the singer. Allen remarks that he has heard several such songs, and I remember hearing one in which the lower note of each couplet was reduplicated, thereby strongly suggested one of the songs of the Blackburnian warbler. Sometimes Mniotilta sings during flight. I once heard a song from a bird flying within a few feet of me—at this range a sound of piercing sharpness.
Of the minor notes Andrew Allison (1907) says: “I know of no other warbler except the Chat that can produce so great a variety of sounds; and since nearly all of the notes resemble those of other warblers, this is a most confusing bird to deal with during the busy season of ‘waves’.”
The call note often has a buzzing quality, and often runs into a long chatter (also characteristic of the young bird), but it may be given so sharply enunciated that it suggests the chip of the black-poll. Allen (MS.) writes it chi, “like pebbles struck together,” and Cordelia J. Stanwood (1910) renders it sptz, saying “the sound resembled the noise made by a drop of syrup sputtering on a hot stove.”
Field marks.—The black-poll, in its spring plumage, and the black-and-white warbler resemble each other in coloration, but the latter bird may be readily distinguished by its white stripe down the center of the crown and the white line over the eye. The contrast in the behavior of the two birds separates them at a glance.
Enemies.—Like other birds which build on the ground, the black-and-white is subject, during the nesting season, to attacks by snakes and predatory mammals. A. D. DuBois (MS.) cites a case in which maggots destroyed a nestful of young birds.
Harold S. Peters (1936) reports that a fly, Ornithoica confluens Say, and a louse, Myrsidea incerta (Kellogg), have been found in the plumage of the black-and-white warbler.