Part 28

HABITS

Alexander Wilson discovered this species near Nashville, Tenn., and gave it the name Nashville warbler. Baird, Brewer, and Ridgway (1874) say of its early history: "For a long while our older naturalists regarded it as a very rare species, and knew nothing as to its habits or distribution. Wilson, who first met with it in 1811, never found more than three specimens, which he procured near Nashville, Tenn. Audubon only met with three or four, and these he obtained in Louisiana and Kentucky. These and a few others in Titian Peale's collection, supposed to have been obtained in Pennsylvania, were all he ever saw. Mr. Nuttall at first regarded it as very rare, and as a Southern species."

This is not strange when we stop to consider that this bird is more or less irregular in its occurrence, apparently fluctuating in numbers in different localities and perhaps choosing different routes of migration. Its record here in eastern Massachusetts illustrates this point. Thomas Nuttall never saw the bird while he lived in Cambridge, from 1825 to 1834. Dr. Samuel Cabot, who lived there from 1832 to 1836, told William Brewster (1906) that he was sure that it did not occur regularly in eastern Massachusetts at that time. According to Brewster:

Soon afterwards a few birds began to appear every season. They increased in numbers, gradually but steadily, until they had become so common that in 1842 he obtained ten specimens in the course of a single morning.

In 1868, and for some fifteen years later, I found Nashville Warblers breeding rather numerously in Waltham, Lexington, Arlington and Belmont, usually in dry and somewhat barren tracts sparsely covered with gray birches, oaks or red cedars, or with scattered pitch pines. A few birds continue to occupy certain of these stations, but in all of the towns just mentioned the Nashville Warbler is less common and decidedly less generally distributed in summer now than it was twenty-five or thirty years ago.

Forbush (1929) found it "more common in eastern Massachusetts in the latter quarter of the last century than it is today." And my own experience has been similar; prior to 1900 we used to consider the Nashville Warbler a common bird on migrations and even found it breeding in Bristol County in 1892; but we have seen very little of it since the turn of the century.

Spring.--From its winter home in Mexico and Central America, the eastern Nashville warbler seems to migrate mainly northeastward through Texas to the lower Mississippi Valley and then west of the Alleghenies to New England and northward up the central valleys. Some individuals apparently fly straight across the Gulf of Mexico, but it is very rare in Louisiana, for which Dr. Oberholser (1938) gives only three records. It seems to be very rare, or entirely unknown, in any of the southeastern States, east of Louisiana and south of Virginia, except in some of the mountains.

According to Dr. Chapman's (1907) tables, about 18 days elapse between the average date of the first arrival of the species in Missouri and that of its first appearance in Minnesota, and it seems to require exactly the same time to migrate from West Virginia to New Brunswick.

Dr. Dayton Stoner (1932) says of its migration through the Oneida Lake region, N. Y.:

The Nashville warbler here seems to prefer coppices along the edges of woodland such as young aspen and maple and elm thickets and other small growth that springs up in cut-over and burned-over areas. In such situations I have found it singing persistently in late May and the first few days in June. This warbler and the chestnut-sided are often found together. However, it does not confine its activities to thickets, for it not infrequently visits woodlands of tall elm, maple, beech and other deciduous trees, as well as mixed forest and the vegetation in door-yards. The flowering currant is in full bloom at the time this bird reaches the height of its abundance and I have seen it visiting such shrubbery during the first part of May.

In Massachusetts in May, according to Forbush (1929), "among its favorite haunts are the bushy edges of woodlands, whether along roads, railroads or streams, or about ponds, lakes, marshes, swamps or open fields. It may often be found among willows, alders, birches or poplars. Old neglected fields and pastures, with scattered growths of birches and bushes, are favorite feeding grounds, but the bird also visits orchards, gardens and shade trees, even in city parks. It may be found on dry lands where scattered pitch pines grow, and on moist lands with rank shrubbery."

W. E. Clyde Todd (1940) says of the migration in western Pennsylvania: "The Nashville Warbler appears during the flood tide of the warbler migration in both spring and fall and is sometimes inordinately abundant. * * *

"Almost every spring there is a day or two of decided movement, when the species is very common and on occasion exceedingly abundant. On May 3, 1901, I witnessed a remarkable flight at Beaver. That morning the woods everywhere were full of Nashville warblers, to the exclusion of almost all other kinds. I counted a dozen in one tree. They kept mostly in the treetops and were singing very little."

These warblers are also sometimes abundant in Ohio, for Milton B. Trautman (1940) noted as many as 80 individuals on May 15, 1932, at Buckeye Lake.

Nesting.--The nesting haunts of the eastern Nashville warbler are quite varied, and habitats similar to some of those frequented on the spring migration seem to be suitable for breeding grounds. But the nest is always placed on the ground and generally is well hidden. Gerald Thayer wrote to Dr. Chapman (1907):

Birch Warbler would be a good name for this bird as it appears in the Monadnock region where it breeds abundantly. For here it is nowhere so common as in abandoned fields and mountain pastures half smothered by small gray birches. From the airy upper story of these low and often dense birch copses the Nashvilles sing; and among the club-mosses and ferns, and the hardhacks and other scrubby brushes at their bases and around their borders, the Nashvilles build their nests. But such is merely their most characteristic home. * * * Dark spruce woods they do not favor, nor big, mixed virgin timber; but even in these places, one is likely to find them wherever there is a little "oasis" of sunlight and smaller deciduous growth. They are fairly common among the scanty spruces, mountain ashes, and white birches of the rocky ridge of Mt. Monadnock, almost to the top--3,169 feet.

F. H. Kennard records in his notes two nests found near Lancaster, N.H. One was among some dead weeds on a mossy hummock in a pasture; the other was in a swamp, at the base of and under a clump of alders beside a path. Miss Cordelia J. Stanwood (1910), of Ellsworth, Maine, writes:

When a growth of evergreens--pine, fir, spruce and hemlock--is cut, it is succeeded by a growth of hard wood--gray, white and yellow birches, maple, poplar, beech, cherry and larch--and vice versa. As the woodland is cut in strips, there are always these growths in juxtaposition. Though the nest of the Nashville is always placed among the gray birches, the inevitable strip of evergreen woodland is near at hand, and a swale not far away.

The nest of the Nashville is sometimes placed in comparatively low ground (that is, compared with its immediate surroundings), in soft green moss under an apology for a shrub, again in the side of a knoll covered with bird wheat (hair-cap) moss, or at other times in an open space in the woodlands under a stump, or tent-like mass of grass, or a clump of gray birch saplings. Around the top is usually woven a rim of coarse, soft, green moss; sometimes dried boulder fern or bracken is added. The side coming against the stump or overhanging moss lacks this foundation. The nest is lined with fine hay, if it abounds in the neighborhood, or pine needles if they are nearer at hand. Sometimes both are used. The red fruit stems of bird wheat moss and rabbit's hair are often employed. One or two birds have preferred some black, hair-like vegetable fibre for lining matter, one bird, horse hair.

Ora W. Knight (1908) mentions a Maine nest that "was situated on the ground on an open wooded hillside at the foot of and between two small spruce trees, and was well imbedded in the moss. It measures in depth outside one and three-fourths inches, and inside one inch, the diameter outside was three and a quarter. * * * Nest building begins soon after the birds have arrived, and presumably the female does most of the work, while the male perches in a near by sapling and sings. * * * It takes from seven to nine days to build the nest, and on its completion an egg is laid each day until the set is completed. The eggs are usually laid between six and ten in the morning."

A nest found by Henry Mousley (1918) near Hatley, Quebec, "was located at the foot of a spirea bush on a little mound, well sunk into the surrounding hair-cap moss (Polytrichum commune) and dwarf cornel or bunchberry (Cornus canadensis) of which the mound was carpeted. It was entirely hidden from sight and would never have been found had I not flushed the female from her set of five eggs."

The only local nest of which we have any record was found by Owen Durfee (MS.) in Rehoboth, Mass., on June 2, 1892. It was only partially concealed among some very low bushes, grass, and other herbage near the foot of a small hill in neglected pasture land; the hill had a scattered growth of oak and beech saplings and had been tramped over by cattle.

Frank A. Pitelka (1940a) found the Nashville warbler breeding in northeastern Illinois in "oak-maple-hickory climax woodland with semi-dense undergrowth, * * * with the stream cutting it and a semi-swampy, sedge-grass area with willow thickets and scattered elms and ashes." In northern Michigan, he found it "in spruce and cedar bogs and in sandy woods of aspen, birch, and Norway pine."

Richard C. Harlow tells me that most of the nests he has found in New Brunswick, about 10, are very frail, but are lined with moose hair. He has found 7 nests in the mountains of Pennsylvania, where the normal lining is deer hair.

Eggs.--The first set of eggs for the Nashville warbler seems to be always either 4 or 5; reported sets of 3 are probably incomplete or late sets. The eggs are ovate or short ovate and are only slightly lustrous. They are white or creamy white, speckled with shades of reddish brown, such as "chestnut" and "auburn," mixed with "light brownish drab." On some eggs the markings are fairly evenly scattered over the entire surface, but usually they are concentrated and form a wreath at the large end. Occasionally eggs are more boldly marked with spots and small blotches or short scrawls; others are nearly immaculate. The measurements of 50 eggs average 15.7 by 12.1 millimeters; the eggs showing the four extremes measure =17.2= by 12.7, 16.4 by =13.0=, =14.5= by 11.6, and 15.2 by =11.5= millimeters (Harris).

Young.--The period of incubation is said to be from 11 to 12 days, and probably the female does most of it, though Mr. Knight (1908) says: "One bird relieves the other on the nest and at times when the eggs are very near the hatching point I have seen the male bring insects to its mate on the nest. Possibly he may feed the female at earlier stages of incubation but I have not seen him do so. Both birds feed the young, giving them at first soft grubs and caterpillars, later on small beetles, flies and similar insects. * * * The young leave about the eleventh day after hatching."

For a further study of the nesting behavior of the Nashville warbler, the reader is referred, to an excellent paper on the subject by Louise de Kiriline Lawrence (1948).

Plumages.--Dr. Dwight (1900) calls the natal down "sepia-brown," and describes the juvenal plumage of the Nashville warbler as follows: