Life Histories of North American Wood Warblers, Part One and Part Two. Arthur Cleveland Bent
all were tinted faint salmon pink by the yolks.” Three to five eggs constitute a set; three seem the usual number, with four a close second, while five are unusual.
[Author’s Note: The measurements of 42 eggs average 15.8 by 12.4 millimeters; the eggs showing the four extremes measure 16.6 by 12.9, 16.5 by 13.0, 14.9 by 12.2, and 15.8 by 11.6 millimeters.]
Plumages.—[Author’s Note: Two young birds, just able to fly from the nest and taken by Wayne on May 13, are thus described by Brewster (1905):
The male which is now before me may be described as follows:—Top and sides of head and fore part of back faded hair brown with a trace of ashy on the middle of crown; remainder of upper parts dull olive green; wings and tail (which are fully grown) as in the first winter plumage excepting that the greater and middle wing-coverts are rather more broadly tipped with light brown, forming two well-marked wing-bars; chin and throat brownish white tinged with yellow; sides of jugulum smoke gray, its center yellowish; sides of breast gamboge yellow shading into olive on the flanks; middle of breast, with most of abdomen, yellowish white; under tail-coverts ashy white. All the feathers on the under parts which are strongly yellow or olive, and those on the upper parts which are decidedly ashy or greenish, appear to belong to the autumnal plumage or, as it is now called, the first winter plumage, but all the other feathers on the head and body are evidently those of the first plumage. * * *
I have not seen the young female Bachman’s Warbler above referred to, but Mr. Wayne writes me that “It differs from the male only in these respects: The yellow on the sides of the breast is very much paler and more restricted and the back is not greenish, but brownish. The white on the tail-feathers is merely indicated on the margins of the inner webs of the tail-feathers.”
It would appear from the above that there is a sexual difference even in the juvenal plumage, and that the postjuvenal molt begins before the middle of May. This molt evidently involves all the contour plumage and the wing coverts but not the rest of the wings or the tail. The young male in first winter plumage is similar to the adult male at that season, but the crown is entirely gray, or with very little black; the feathers of the black patch on the throat, which is more restricted, are tipped with yellowish or buffy. There are no specimens available that indicate a prenuptial molt, which is probably very limited. Young males in the first nuptial plumage may be recognized by the worn and faded wings and tail.
The complete postnuptial molt of adults apparently occurs in July or earlier; I have seen no molting birds, but a large series of August birds are all in completely fresh winter plumage. In this plumage the male resembles the spring male, but the black of the crown is widely tipped with gray and the black of the breast is narrowly tipped with yellowish; these tips largely wear away before spring, although Wayne (1910) says that his “breeding males all show the olive yellow edging on the black feathers.” Similar molts and changes take place in the female, but she has no black in the crown and much less or none at all on the breast; her colors are duller and she has less white in the tail, as well as olive-green, instead of yellow, lesser wing coverts.
For a full description of individual variations in plumage, the reader is referred to Mr. Brewster’s (1891) excellent paper.]
Food.—Very little information is to be found concerning the food of this warbler, but insects undoubtedly constitute its diet. Howell (1924) says: “Five stomachs of this species from Alabama contained remains of caterpillars and a few fragments of Hymenoptera, probably ants.”
Behavior.—Wayne (1907), in writing of this bird on its breeding grounds, says: “Bachman’s Warbler is a high-ranging bird, like the Yellow-throated Warbler, and generally sings from the top of a sweet gum or cypress. It appears to have regular singing stations during the breeding season, and upon leaving a tree it flies a long distance before alighting. On this account it is impossible to follow the bird through the dark forest, and it can only be detected by its song. I have occasionally seen the males in low gall-berry bushes within six or eight inches of the ground, but their usual resorts are among the topmost branches of the tallest forest trees.”
Brewster (1891) had similar experience with migrating birds in Florida:
Nearly or quite all that has been hitherto written about this Warbler would lead one to infer that its favorite haunts are dense thickets, undergrowth, or low trees, and that it seldom ventures to any considerable height above the ground. Our experience, however, was directly contrary to this. * * * The bird, moreover, not only frequented the tops of the tallest trees, but at all times of the day and under every condition of weather kept at a greater average height than any other Warbler excepting Dendroica dominica. In its marked preference for cypresses it also resembled the species just named, but unlike it was never seen in pines. * * *
At the time of our visit the Suwanee bottoms were alive with small birds many of which were doubtless migrants. They banded together in mixed flocks often of large size and motley composition. * * * Such a gathering was nearly certain to contain from one or two to five or six Bachman’s Warblers.
These with the Parulas were most likely to be feeding in the upper branches of some gigantic cypress, at least one hundred feet above the earth, where they looked scarcely larger than bumble bees. * * *
The habits and movements of Bachman’s Warbler are in some respects peculiar and characteristic. It does not flit from twig to twig nor launch out after flying insects in the manner of most Warblers, and many of its motions are quite as deliberate as those of a Vireo. Alighting near the end of a branch it creeps or sidles outward along a twig, and bending forward until the head points nearly straight down, inserts the bill among the terminal leaflets with a peculiar, slow, listless motion, keeping it there a second or two, and repeating the leisurely thrust many times in succession without changing its foothold. The action is like that of several other members of the genus—notably H. pinus and H. chrysoptera—under similar conditions, and suggests the sucking in of liquid food, perhaps honey or dew. Not infrequently a bird would hang back downwards beneath a twig and feed from the under sides of the leaves in the manner of a Titmouse. * * *
Many of the hackberry trees along the banks of this stream contained compact bunches—nearly as large as a child’s head—of dead leaves blackened by exposure to wind and weather. These bunches probably sheltered insects or their larvae, for they attracted several species of birds, especially the Bachman’s Warblers which would work at them minutes at a time with loud rustling, sometimes burrowing in nearly out of sight and sending the loosened leaves floating down to the ground. Upon exhausting the supply of food or becoming tired of the spot—whether one of the leaf bunches or the extremity of a cypress branch—the bird almost invariably started on a long flight, often going hundreds of yards through the woods or crossing the river, instead of merely passing to the next branch or tree as almost any other Warbler would have done under similar circumstances. This habit seemed to us characteristic of the species.
Atkins wrote from Key West (Scott, 1890):
Bachman’s Warbler in its habits is very much like the Parula Warbler (Compsothlypis americana). The resemblance is more noticeable when feeding and in search of food. The birds will then penetrate a thick bunch of leaves and go through, over and all around in the most thorough manner in their exploration after insects that appeal to their taste. They are very active, and constantly in motion. They are also quarrelsome, and resent the intrusion of other species. Frequently I have noticed them fighting away the White-eyed Vireo, and where two or more Bachman’s Warblers are observed together, one is pretty sure to see them chasing and fighting among themselves. When disturbed or alarmed they are at once alert; a sharp alarm note, something like that of a Yellow-throated Warbler (D. dominica) is uttered, but more forcible and clear cut in its delivery. This is accompanied with a few jerks of the tail, and the bird is off to a neighboring tree. They are found alike in the trees, low bushes, and shrubbery, sometimes on or quite near the ground, and seem to prefer the heavy and more thickly grown woods to trees or bushes more in the open. Young birds are quite tame, but the adults as a rule were very shy and difficult to approach after having been once disturbed.
Voice.—The song of Bachman’s warbler is of a wiry