Part 2

In the second category is _Vermivora cincinnatiensis_ (Langdon), the Cincinnati warbler, described in 1880. "The unique type is regarded as a hybrid between _Vermivora pinus_ (Linnaeus) and _Oporornis formosa_ (Wilson)." Recently, in a letter dated August 3, 1948, Dr. George M. Sutton reports to Mr. Bent the discovery of a second Cincinnati warbler, taken in Michigan on May 28, 1948. He says: "Its bill and feet are large for _Vermivora_ and its under tail coverts proportionately too long for that genus. It has only a faint suggestion of wing-barring and the merest shadow of a pattern on the outer rectrices. One of its most interesting and beautiful characters is the gray tipping of the feathers at the rear of the crown, as in _O. formosus_. The effect is very unusual, for the gray-tipped feathers are yellow. It is, in short, obviously a cross between _Vermivora_ and _Oporornis_."

The status of _Vermivora leucobronchialis_ and _V. lawrencii_ and the relationship between them puzzled ornithologists for upward of two generations. William Brewster (1876) described the former as a new species, and since that time, as Walter Faxon (1911) writes, "almost every conceivable hypothesis has been advanced by one writer or another to fix its true status in our bird-fauna." In addition to being considered a valid species, it has been regarded as a hybrid (Brewster, 1881), as a dichromatic phase, that is, a leucochroic phase of _V. pinus_ (Ridgway, 1887), as a mutant (Scott, 1905), and finally as a phase, "ancestral in character" (atavistic) of the goldenwing (C. W. Townsend, 1908).

Lawrence's warbler is a very rare bird. The first specimen was described in 1874 (Herold Herrick, 1874), and since that time the bird was taken or seen infrequently, chiefly in regions where the breeding ranges of _V. chrysoptera_ and _V. pinus_ overlap. Consensus of opinion in the main regarded it as a hybrid between _V. chrysoptera_ and _V. pinus_, as it combined characters of both the supposed parents. John Treadwell Nichols (1908) some years ago brought new light to the problem. He says:

In any discussion of the status of Lawrence's and Brewster's Warblers it is well to bear in mind the facts, including the much greater abundance of Brewster's, are in accord with Mendel's Law of Heredity, supposing both forms to be hybrids between _Helminthophila pinus_ and _H. chrysoptera_. * * * All the first generation hybrids will be Brewster's Warbler in plumage. In the next generation there will be pure Golden-winged Warblers, pure Blue-winged Warblers, pure Brewster's Warblers, and pure Lawrence's Warblers; also mixed birds of the first three forms, but none of the last form, which, being recessive, comes to light only when pure. The original hybrids then (which will be all Brewster's in plumage) must be fertile with one another or with the parent species for any Lawrence's to occur; and if they are perfectly fertile Lawrence's must still remain a small minority. After the first generation the proportion of plumages of birds with mixed parentage should be: 9 Brewster's, 3 _chrysoptera_, 3 _pinus_, 1 Lawrence's.

This explanation removed the stumbling block, long believed to be insurmountable, that a black-throated bird, mating with a yellow-throated bird, could produce progeny having a white throat. Under Mendel's Law the dominant color (white) of _chrysoptera_ would appear by the suppression of the recessive black throat.

Fortunately, Walter Faxon (1913) not long afterward found a female blue-winged warbler mated with a goldenwing and was successful in following the resulting brood of young birds until they had acquired their first winter plumage when, fulfilling Mendel's Law, they were all in "the garb of _Helminthophila leucobronchialis_," thus establishing beyond a doubt the hybrid nature of the bird. At the end of his paper, Walter Faxon (1913) relates a bit of interesting ancient history regarding these three species of _Vermivora_. He says:

In my paper published in 1911, after stating the different hypotheses proposed in order to explain the relations existing among the Golden-winged, Blue-winged, Brewster's, and Lawrence's Warblers I added, half in jest, that the only hypothesis left for a new-comer in the field was this: that the Golden-winged and the Blue-winged Warblers themselves were merely two forms of one species. Curiously enough, not long after this I found that this very opinion had been expressed, and in a most unexpected quarter: in a letter dated Edinburgh, Sept. 15, 1835, Audubon wrote to Bachman that he suspected the golden-winged warbler and the blue-winged warbler were one species! That Audubon at that early date, ignorant (as he was assumed to be) of the existence of Brewster's and Lawrence's warblers, and but superficially acquainted with the golden-wing, should suspect that two birds so diverse as the blue-wing and the golden-wing were one species seemed incomprehensible, and in the light of what we now know about these birds, his surmise seemed to presuppose an almost superhuman faculty of prevision.

As a possible explanation of Audubon's letter I have only this to offer: in the winter of 1876-77 Dr. Spencer Trotter discovered in the collection of the Academy of Natural Sciences of Philadelphia a specimen of Brewster's warbler without a label, the third specimen known up to that time; on the bottom of the stand was written in the autograph of John Cassin, "J. C., 20 October, 1862," and also a badly blurred legend "Not from Bell." An appeal to J. G. Bell elicited the response that he remembered shooting a peculiar warbler in Rockland Co., N. Y., about the year 1832--a warbler something like a golden-wing, but lacking, although in high plumage, the black throat of that species; a great many years afterward, he sold this specimen in Philadelphia but knew nothing of its ultimate fate. Dr. Trotter justly inferred that the Philadelphia Academy specimen was in all probability the very bird shot by Bell.

Now as Audubon was intimately associated with Bell, is it not possible that he had examined this example of Brewster's warbler? In that case, seeing that this bird's characters were in part those of the blue-wing, in part those of the golden-wing, he may have inferred the interbreeding of these two birds, and so (rather unwarrantably, it is true) their identity. If this be not the explanation of the passage in Audubon's letter to Bachman I have no other to suggest.

When Audubon came to publish his account of the Golden-winged Warbler in 1839 (Ornithological Biography, 1839, 5, p. 154) he said not a word about its connection with the Blue-winged Warbler.

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.

[AUTHOR'S NOTE: Since the above was written, Kenneth C. Parkes (1951) has published a study of the genetics of the golden-winged--blue-winged warbler complex, to which the reader is referred.]

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:

In its excursions over the trunks and larger limbs of trees the Black and White Creeper is certainly not looking for vegetable food, and only a trace of such matter has been found in the stomachs examined. The food is chiefly insects but considerable numbers of spiders and daddy-long-legs also are eaten. Beetles, caterpillars, and ants are the larger classes of insect food, but moths, flies, bugs, and a few hymenoptera also are eaten. Among forest enemies that have been found in stomachs of this species are round-headed wood borers, leaf beetles, flea beetles, weevils, bark beetles, leaf hoppers, and jumping plant lice. The hackberry caterpillar, the hackberry psyllid, an oak leaf beetle _Xanthonia 10-notata_, and the willow flea beetle, are forms specifically identified. Observers have reported this warbler to feed also upon ordinary plant lice, and upon larvae of the gypsy moth.

Forbush (1929) adds the following observation: "The food of this bird consists mostly of the enemies of trees, such as plant-lice, scale-lice, caterpillars, both hairy and hairless, among them such destructive enemies of orchard, shade and forest trees as the canker-worm and the gipsy, brown-tail, tent and forest tent caterpillars. Wood-boring and bark-boring insects, click beetles, curculios and many other winged insects are taken. Sometimes when the quick-moving insects escape its sharp bill, it pursues them on the wing but most of its attention is devoted to those on the trees."

H. H. Tuttle (1919), speaking of the male parent feeding the young birds, says: "The fare which he provided was composed entirely of small green caterpillars, cut up into half-lengths."

_Behavior._--The black-and-white warbler seems set apart from others of the group, perhaps because of its marked propensity for clambering over the trunks of trees and their larger branches. Although, like other warblers, it seems at home among the smaller twigs, it spends a large part of its time on upright surfaces over which it moves easily and quickly, upward, downward, and spirally, with great agility and sureness of footing, constantly changing direction, and not using the tail for support. As it scrambles over the bark, it switches from side to side as if at each hop it placed one foot and then the other in advance, and even on slim branches it hops in the same way, the tail alternately appearing first on one side of the branch and then on the other; it reminds us of a little schoolgirl swishing her skirt from side to side as she walks down the street. The bird is alert and watchful, and if it starts an insect from the bark, or sees one flying near, it may pursue it and catch it in the air.

H. H. Tuttle (1919) describes an extreme example of behavior simulating a wounded bird. He says: "She struck the leaves with a slight thud and turned over on her side, while the toes of one up-stretched leg clutched at the air and her tail spread slowly into a pointed fan. * * * Deceived for a moment then, I turned a step in her direction. She lay quite still except for a quivering wing. I reached out toward her with a small stick and touched her side; she screamed pitifully; I stretched out my hand to pick her up, but with a last effort she righted herself, and by kicking desperately with one leg, succeeded in pushing forward a few inches."

We associate this warbler with dry, rocky hillsides where the ground is strewn with dead leaves, but the bird may breed also in the dry portions of shady, wooded swamps.

_Voice._--The black-and-white is one of the high-voiced singers. Its song is made up of a series of squeaky couplets given with a back-and-forth rhythm, a seesawing effect, like the ovenbird's song played on a fine, delicate instrument. It may be suggested by pronouncing the syllables _we see_ rapidly four or five times in a whispered voice. In the distance the song has a sibilant quality; when heard near at hand a high, clear whistle may be detected in the notes. The final note in the song is the accented _see_.

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.