Part 6

Recently Karl W. Haller (1940) described "a new wood warbler from West Virginia" from two specimens, male and female, which he collected on May 30 and June 1, 1939, respectively, at points 18 miles apart, and proposed for it the new name Dendroica potomac, Sutton's warbler. These birds resemble the yellow-throated warbler in plumage but lack streaks on the sides. They also suggest the parula warbler in having a faint yellowish wash on the back and, in the male, "an almost imperceptible hint of raw sienna" on the upper breast. The male sang a song much like the parula's, but doubled by repetition.

Two more Sutton's warblers have been carefully observed in the field: one at the point where the type was collected on May 21, 1942, by Maurice Brooks and Bayard H. Christy (1942); the second about 18 miles to the westward on June 21, 1944, by George H. Breiding and Lawrence E. Hicks (1945). Another aberrant warbler has been described by Stanley G. Jewett (1944), who examined four specimens which show a curious intermingling of the plumage characters of the hermit and Townsend warblers.

MNIOTILTA VARIA (Linnaeus)

BLACK-AND-WHITE WARBLER

CONTRIBUTED BY WINSOR MARRETT TYLER

PLATES 1-3

HABITS

The black-and-white warbler is one of the earliest spring warblers to reach its breeding-ground in the Transition Zone. Most of the other members of this family arrive in or pass through the region in mid-May or somewhat later, according to the season, when the oaks are in bloom and the opening flowers attract swarms of insects.

The black-and-white warbler, however, owing to its peculiar habit of feeding on the trunks and the large limbs of the trees, does not have to wait for the bounty supplied by the oaks but finds its special feeding-ground well stocked with food long before the oaks blossom or their leaves unfold. It comes with the yellow palm warbler late in April, when many of the trees are nearly bare, and not long after the pine warbler.

Mniotilta is a neat little bird, dressed in modest colors, at this season singing its simple but sprightly song as it scrambles over the bark--the black-and-white creeper, Alexander Wilson calls it.

Milton B. Trautman (1940), speaking of the spring migration at Buckeye Lake, Ohio, shows that the male birds are preponderant in the earliest flights. He says: "The first spring arrivals, chiefly males, were noted between April 16 and 30, and between May 1 and 5, 2 to 15 birds, mostly males, could be daily noted. The peak of migration usually lasted from May 6 to May 18, and then from 3 to 42 individuals, consisting of a few old males and the remainder females and young males, were daily observed. On May 18 or shortly thereafter a decided lessening in numbers occurred, and by May 23 all except an occasional straggler had left."

Courtship.--Forbush (1929) gives this hint of courtship, which resembles the activities of most warblers at this season: "When the females arrive there is much agitation, and often a long-continued intermittent pursuit, with much song and fluttering of black and white plumage, and much interference from rival males before the happy pair are united and begin nesting."

Nesting.--The black-and-white warbler usually builds its nest on the ground, tucking it away against a shrub or tree, or even under the shelter of an overhanging stone or bank. The nest is generally concealed among an accumulation of dead leaves which, arching over it, hides it from above. It is made, according to A. C. Bent (MS.), "of dry leaves, coarse grass, strips of inner bark, pine needles and rootlets, and is lined with finer grasses and rootlets and horsehair." I have seen a nest made chiefly of pine needles on a base of dry leaves.

Henry Mousley (1916), writing of Hatley, Quebec, mentions moss as a component part of the nest, and says of three nests that they were all "heavily lined with long black and white horse hairs," a peculiarity of coloration mentioned in one of Mr. Bent's nests. Thomas D. Burleigh (1927b) speaks of a nest in Pennsylvania "built of dead leaves and rhododendron berry stems, lined with fine black rootlets and a few white hairs." H. H. Brimley (1941) describes an exceptional nest. He says: "There was no particular departure from normal in its construction except for the fact that it was lined with a mixture of fine rootlets and very fine copper wire, such as is used in telephone cables. Fragments of such cable, discarded by repair men, were found nearby where a telephone line ran through the woods."

Cordelia J. Stanwood (1910c) speaks of a nest "built in a depression full of leaves, behind a flat rock. * * * The cavity was shaped on a slant, the upper wall forming a partial roof. * * * It looked not unlike a small-sized nest of an Oven-bird. On the inside, the length was 2-1/2 inches, width 1-1/2 inches, depth 2 inches. On the outside, length 3-1/2 inches, width 2-1/2 inches, depth 2-1/2 inches. Thickness of wall at the top of nest, 1 inch; at the bottom, 1/2 inch." Henry Mousley (1916) gives the average dimensions of three nests as "outside diameter 3-3/4, inside 1-3/4 inches; outside depth 2-1/4, inside 1-1/2 inches."

F. A. E. Starr (MS.) writes to A. C. Bent from Toronto, Ontario, that all the nests he has found have been in broken-off stumps in low woods. "The cavity in the top of the stump," he says, "is filled with old leaves, and the nest proper is made chiefly of strips of bark with grass and fiber." Guy H. Briggs (1900) reports a nest "in a decayed hemlock stump, fifteen inches from the ground." In such cases, of course, while the nest is well above the ground level, it rests on a firm foundation.

Audubon (1841) says: "In Louisiana, its nest is usually placed in some small hole in a tree," but he quotes a letter to him from Dr. T. M. Brewer on the subject, thus: "This bird, which you speak of as breeding in the hollows of trees, with us always builds its nest on the ground. I say always, because I never knew it to lay anywhere else. I have by me a nest brought to me by Mr. Appleton from Batternits, New York, which was found in the drain of the house in which he resided."

Minot (1877) speaks of two nests found near Boston, Mass., well above the ground. He says: "The first was in a pine grove, in the cavity of a tree rent by lightning, and about five feet from the ground, and the other on the top of a low birch stump, which stood in a grove of white oaks."

Gordon Boit Wellman (1905) states: "Toward the last of the incubation time one of the birds was constantly on the nest. I found the male sitting usually at about dusk, but I think the female sat on the eggs over night."

Eggs.--[AUTHOR'S NOTE: The black-and-white warbler usually lays 4 or 5 eggs to a set, normally 5, seldom fewer or more. These are ovate to short ovate and slightly glossy. The ground color is white or creamy white. Some are finely sprinkled over the entire surface with "cinnamon-brown," "Mars brown," and "dark purplish drab"; others are boldly spotted and blotched with "russet" and "Vandyke brown," with underlying spots of "brownish drab," "light brownish drab," and "light vinaceous-drab." Speckled eggs are commoner than the more boldly blotched type. The markings are usually concentrated at the large end, and on some of the heavily spotted eggs there is a solid wreath of different shades of russet and drab. The measurements of 50 eggs average 17.2 by 13.3 millimeters; the eggs showing the four extremes measure =18.8= by 13.7, 17.9 by =14.7=, =15.7= by 12.7, and 16.3 by =12.2= millimeters (Harris).]

Young.--Cordelia J. Stanwood (MS.) speaks of the nestlings a few days from the egg as "very dark gray, much like young juncos and Nashville warblers." But when they leave the nest they are clearly recognizable as young black-and-white warblers, although they are slightly tinged with brownish. By mid-July, here in New England, they assume their first winter plumage, and, as both sexes of the young birds have whitish cheeks, they resemble very closely their female parent.

Unlike the young of some of the other warblers which remain near the ground for many days, the young black-and-white warblers shortly ascend to the branches of trees where they are fed by the old birds.

I find no definite record of the length of the incubation period, but in a nest I watched in 1914 it was close to 10 days. Burns (1921) gives the period of nestling life as 8 to 12 days.

Plumages.--[AUTHOR'S NOTE: Dr. Dwight (1900) calls the natal down mouse gray, and describes the juvenal plumage as follows: "Above, wood-brown streaked with dull olive-brown, the upper tail coverts dusky; median crown and superciliary stripe dingy white. Wings and tail dull black, edged chiefly with ashy gray, the tertiaries (except the proximal which is entirely black) broadly edged with white, buff tinged on the middle one. Two buffy white wing bands at tips of greater and median wing coverts. The outer two rectrices with terminal white blotches of variable extent on the inner webs. Below, dull white, washed on the throat and sides with wood-brown, obscurely streaked on throat, breast, sides and crissum with dull grayish black."

A postjuvenal molt begins early in July, involving everything but the flight feathers; this produces in the young male a first winter plumage which is similar to the juvenal, but whiter and more definitely streaked. "Above, striped in black and white, the upper tail coverts black broadly edged with white; median crown and superciliary stripe pure white. The wing bands white. Below, pure white streaked with bluish black on sides of breast, flanks and crissum, the black veiled by overlapping white edgings; the chin, throat, breast and abdomen unmarked. Postocular stripe black; the white feathers of the sides of the head tipped with black."

The first nuptial plumage is acquired by a partial prenuptial molt in late winter, which involves a large part of the body plumage, but not the wings or the tail. "The black streaks of the chin and throat are acquired, veiled with white, and the loral, subocular and auricular regions become jet-black. The brown primary coverts distinguish young birds and the chin is less often solidly black than in adults."

The adult winter plumage is acquired by a complete postnuptial molt, beginning early in July. It differs from the first winter dress "in having the chin and throat heavily streaked with irregular chains of black spots veiled with white edgings, the wings and tail blacker and the edgings a brighter gray. * * * The female has corresponding plumages and moults, the first prenuptial moult often very limited or suppressed. In juvenal dress the wings and tail are usually browner with duller edgings and the streaking below obscure. In first winter plumage the streakings are dull and obscure everywhere, a brown wash conspicuous on the flanks and sides of the throat. The first nuptial plumage is gained chiefly by wear through which the brown tints are largely lost, the general color becoming whiter and the streaks more distinct. The adult winter plumage is rather less brown than the female first winter, the streaking less obscure and the wings and tail darker. The adult nuptial plumage, acquired partly by moult, is indistinguishable with certainty from the first nuptial."]

Food.--McAtee (1926) summarizes the food of the species thus: