Part 29

"Pileum hair-brown, back darker, olive tinged, and rump olive-green. Below, pale yellowish wood-brown, straw-yellow on abdomen and crissum. Wings and tail olive-brown broadly edged with bright olive-green, the median and greater coverts tipped with pale buff-yellow forming two wing bands. Lores and auriculars mouse-gray, the orbital ring pale buff."

The sexes are alike in juvenal plumage. A postjuvenal molt occurs in July and August that involves the contour plumage and the wing coverts but not the rest of the wings or the tail. This produces a first winter plumage in which young birds become practically indistinguishable from adults in many cases, but the chestnut crown patch is generally smaller and more veiled in the younger male and is often lacking in the young female.

Dr. Dwight (1900) says that the first nuptial plumage is "acquired by a partial prenuptial moult which involves chiefly the crown, sides of head and throat, but not the rest of the body plumage nor the wings and tail. The head becomes plumbeous gray, the edgings only half concealing the rich chestnut of the crown. The orbital ring is white and conspicuous. Wear is marked, bringing the gray of the nape into contrast with the greenish back, later exposing the chestnut of the crown."

A complete postnuptial molt in July and August produces the fully adult plumage. In fresh fall plumage the head is browner than in spring, the back is grayer, the crown patch is more veiled with gray tips, and the breast is tinged with brownish. The females are paler than the males, with less chestnut in the crown. Adults probably have a partial prenuptial molt similar to that of young birds.

Food.--Very little has been published on the food of the Nashville warbler. Knight (1908) says that "the food of the adults consists of beetles, larvae of various insects and the eggs of various insects. In fact they eat almost anything which they can glean in the insect line from the shrubbery and ground."

Forbush (1929) says: "As the bird ranges from the ground to the tree-tops it takes most of the insects that any warbler will eat, among them flies, young grasshoppers and locusts, leaf-hoppers and many plant-lice, caterpillars both hairless and hairy, among them the gipsy, brown-tail and tent caterpillar, most of which are taken when young and small; also small wood-boring beetles are eaten, and other small insects of many species. The bird appears to be almost wholly insectivorous."

Behavior.--The eastern Nashville warbler is an active, sprightly, restless member of an active family, ranging in its foraging mainly in the lower story of the open woodlands and more often in the low trees and shrubbery around the borders of the forest. When thus engaged it is not particularly shy and often seems quite unconscious of the presence of an observer. On migrations it seems to be sociably inclined and may be seen associated with the mixed flocks of warblers that are drifting through the tree tops. At these seasons it often visits our orchards and the shrubbery in our gardens, giving us a glimpse of green and gold among the blossoms and opening leaves.

J. W. Preston (1891) describes an interesting manner of foraging:

"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 1-2/5 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.

"The nesting song may be heard commonly on the breeding grounds. I have several records from the Adirondacks. This song is in three or four parts, each part of three or four notes, and a little lower in pitch than the preceeding part. Two-note phrases are not commonly heard in the nesting song."

Francis H. Allen's rendering of the song is not very different from the first one of Mr. Saunders', though he noted some variation, and mentions in his notes an aberrant song, which "doubled the common song, which in this case had a first part consisting of only a single phrase, thus; chip-ee-(trill) chip-ee-(trill)."

Field marks.--The gray head, white eye ring, olive-green back, bright yellow under parts, and the absence of wing bars, with no white in the tail, are the distinguishing marks of the eastern Nashville warbler. The Connecticut warbler has a white eye ring but it has a gray throat, whereas the Nashville is bright yellow from chin to abdomen. The chestnut crown patch is not very conspicuous in the male and is less so, or entirely lacking, in the female; the female is duller yellow below and browner above than the male.

Enemies.--Like other ground-nesting birds, this warbler has the usual four-footed enemies to contend with, but its nest is quite well hidden. Perhaps its worst bird enemy is the cowbird, although Friedmann (1934) listed it as an uncommon victim of this parasite and had only six records of it, the nests containing from one to two eggs of the cowbird.

Fall.--As soon as the molting season is over and the young birds are freshly clad in their winter dress the migration begins in Massachusetts. This takes place in August, and the last stragglers may be seen passing through in early October.

In Ohio, according to Mr. Trautman (1940), the first migrants are seen about the first of September, the peak of the migration coming during the latter half of that month when from 10 to 100 could be found in a day, and after the 10th of October only an occasional bird remains. He writes: "As with many other transient warblers the southward migration of the Nashville Warbler covered a greater period of time than did the spring movement, which usually lasted less than 30 days, whereas the fall movement generally extended more than 45 days. * * * In spring the species frequented the upper half of large trees and was more numerous in tall trees of woodlands than it was in smaller groups or rows of tall trees. In fall the species tended to inhabit the middle section of large trees, and it also resorted to the taller bushes and saplings, especially the larger hawthorn trees."

The fall migration route is apparently a reversal of the spring route southwestward into Mexico and Central America where it spends the winter.

Winter.--The Nashville warbler is evidently very common in winter in certain parts of Mexico, for Dr. C. William Beebe (1905) says: "At times there were twenty and thirty in sight at once near our camp in the Colima lowlands." These may have been the western race.

DISTRIBUTION

Range.--Southern Canada to Guatemala.