“One will fly to the foot of a fir tree or other conifer and begin an upward search, hopping energetically from branch to branch until the very highest point is reached, when the bird drops lightly down to the foot of another tree, much as does the Brown Creeper. When an insect is discovered the bird secures it by a sudden bound, and, should the object be not easily dislodged, Helminthophila sustains himself on flapping wings until his purpose is accomplished, which often requires several moments.”
Voice.—Gerald Thayer gave Dr. Chapman (1907) a very good description of the songs and calls as follows:
The Nashville has at least two main perch-songs, and a flight-song, all subject to a good deal of variation. It belongs decidedly among the full-voiced Warblers. * * * Its commoner perch-song consists of a string of six or eight or more, lively, rapid notes, suddenly congested into a pleasant, rolling twitter, lower in key than the first part of the song, and about half as long. In the other perch-song, the notes of what correspond to the rolling twitter are separate and richer, and the second part of the song is longer and more noticeable than the first, whose notes are few and slurred, while the whole is more languidly delivered.
The differences are hard to describe intelligibly; but in reality they are pronounced and constant. The flight-song, a fairly common performance in late summer, is sung from the height of five to forty feet above the (usually low) tree-tops. It is like the commoner perch-songs, but more hurried, and slightly elaborated, often with a few chippings added, at both ends. Among the Nashville’s calls a very small, dry chip, and a more metallic, louder chip, somewhat Water-Thrush-like, are noteworthy. It also chippers like a young Warbler or a Black-throated Green.
Miss Stanwood (1910a) writes:
One common song sounds like ‘tsin, ‘tsin, ‘tsee, another sweeten, sweeten, ‘tsee, a third, sillup, sillup, sillup, ‘tsee-e-e-e-e-e. At other times the bird sings but part of the song as sweeten, sweet; or sweeten, ‘tsee; or sweeta, sweeta, ‘tsee; or recombines them differently as sweeten, sweeten, sweeten, ‘tsee-e-e-e-e-e. * * *
The song is loud, constant, and heard all over the locality, coming principally from the gray birches, but also from the maples, poplars, and evergreens. The bird sings from the tree-tops, but likewise from the middle branches, and I have seen it singing on the ground and just a few inches above it. My last record of its song in 1908 was made the 17th day of July, the first, May the 14th. Between these dates it sang well-nigh incessantly.
Knight (1908) says that, while the female is building the nest, “the male bird perches in a nearby sapling and sings leisurely 'pea-cie-pea-cie-hit-i-hit-i-hit.'” Wilson (1832) thought that the “notes very much resembled the breaking of small dry twigs, or the striking of small pebbles of different sizes smartly against each other for six or seven times, and loud enough to be heard at the distance of thirty or forty yards.” Rev. J. H. Langille (1884) writes: “The song of the Nashville Warbler is a composition, the first half of which is as nearly as possible like the thin but penetrating notes of the Black-and-white Creeping Warbler, while the last half is like the twitter of the Chipping Sparrow.” He writes it in syllables as “ke-tsee-ke-tsee-ke-tsee-chipe-ee-chip-ee-chip-ee-chip.”
The song has been said to resemble that of the chestnut-sided warbler, but the two are really quite distinct; the song of the latter does not end in a trill or in chipperings. It does, however, more closely resemble the song of the Tennessee warbler. Dr. Roberts (1936) heard the two singing at the same time and noted this difference: “The Nashville’s song is an utterance of rather greater volume than that of the Tennessee and differs, also, in the fact that it has a short, rapidly weakening trill or slide, following a rather long and deliberate prelude of four or five notes; while the Tennessee has a brief prelude with a long finishing trill, increasing in loudness and intensity to an abrupt ending.”
Aretas A. Saunders contributes the following study of the song: "The territory song of the Nashville warbler is in two parts, the first a series of 2-note phrases, and the second a series of rapid notes, commonly lower in pitch and just twice as fast as the notes of the first part; pa tipa tipa tipa tipa tititititititit. In 26 of my 29 records the second part of the song is lower than the first. In the other three it is higher. "The pitch of songs varies from G‴ to F sharp‴′, or five and a half tones. Single songs rarely vary more than one and a half or two tones. They are from 12⁄5 to 2 seconds in length. The quality is rather musical, and some individuals have almost as sweet a tone as the yellow warbler. In my experience field students often confuse the songs of these two species.