Life Histories of North American Wood Warblers, Part One and Part Two. Arthur Cleveland Bent
of the young of chrysoptera which he and I watched year after year together. Both parents are very attentive to their young brood, bringing to them food which they find both on low plant growth and high in the overshadowing branches.
The fledglings call to their parents with a very characteristic note, a little quavering, high, fine chirp which I find written in my journal crrr and tzzz. It suggests somewhat a note of young chipping sparrows, but is less sharp and crisp. In form it also resembles the call of the young cowbird, but again it is gentler and weaker in tone. Mr. Faxon (1911) refers to it as the “cricket note.” The young birds acquire their first winter plumage about a month after they leave the nest, and hence to the eye are indistinguishable from their parents, but as they still continue to use the call of their babyhood, they may be recognized as immature birds even when they are feeding high up in the trees.
Plumages.—[Author’s Note: I can find no description of the natal down. Dr. Dwight (1900) describes the juvenal plumage, in which the sexes are practically alike, as "above, grayish or brownish olive-green. Wings and tail slate-black edged chiefly with bluish plumbeous gray, the coverts and tertiaries with olive-green. Below, pale olive-yellow, the throat dusky. Transocular streak dusky. * * *
“First winter plumage acquired by a partial postjuvenal moult, beginning early in July, which involves the body plumage and wing coverts, but not the rest of the wings nor the tail, young and old becoming practically indistinguishable.” He describes the young male in this plumage as—
above, plumbeous gray veiled with olive-green edgings; the crown bright lemon-yellow veiled posteriorly only. Below, grayish white, with yellow edgings here and there, the chin, jugulum, lores and auriculars jet-black veiled slightly with pale buff. Broad submalar stripes joining at angle of the chin, and superciliary lines white. Outer half of median and greater coverts bright lemon yellow forming an almost continuous wing patch, lesser coverts plumbeous gray, edged with olive-green.
First nuptial plumage acquired by wear, through which the buff edgings of the black areas, the olive edgings of the back and the yellow edgings below are almost completely lost, the plumage becoming clear gray, white, yellow and black.
Of the female, he says: “In first winter and other plumages olive-gray, dusky on the lores and auriculars, replaces the black areas of the male, and olive-yellow marks the crown. Above, the plumage is greenish; the submalar stripes are grayish.” Subsequent plumages are acquired by a complete postnuptial molt in late June and July and by wear in early spring.]
Food.—Little exact information has been gathered regarding the food of the goldenwing. The insects it feeds on are mainly so small that it is generally impossible to identify them. Jacobs (1904) states: “Once I saw a female carry a small brownish butterfly to her young; and several times I have discovered the birds taking small smooth green worms—such as strip the leaves of their green coat, leaving the ribbed skeleton—to their nestlings. The legs of a spider protruded from a bird’s bill as she approached her nest.”
The little pale green larva which Jacobs mentions impresses us as the chief article of food, as we watch the birds. It is 1⁄2 to 3⁄4 inch long and appears to have a smooth, hairless skin. These larvae are obtained, I believe, chiefly in the large trees.
In the following note A. L. Nelson (1933) furnishes an interesting detail of the bird’s diet:
The following observation on the food habits of a Golden-winged Warbler (Vermivora chrysoptera), made in the vicinity of Port Tobacco (Charles Co.), Maryland on May 6, 1933, seems worthy of mention, inasmuch as little specific information on the dietary habits of this species has been recorded. About 1:30 we observed a single individual of this species actively feeding in a low shrubbery growth of pawpaw (Asimina triloba), which was in full bloom at this date. Closer observation revealed that the bird was probing about inside the flowers, and apparently was getting some kind of larvae. Examination of the flowers revealed that they were infested with a small, brown-headed lepidopterous larva. Dissection of a large number of flowers indicated that the infestation was high, the majority of flowers having one larva, although in many cases two were present. Several infested flowers were collected for the purpose of rearing the insects to the adult stage under laboratory conditions. The cycle was completed without difficulty, the adults emerging within twelve days. These were examined by Dr. Carl Heinrich of the U. S. National Museum and found to be Talponia plummeriana Busck, a small brightly colored Tortricid, the only known food plant of which is the pawpaw.
Behavior.—A favorite locality for the golden-winged warbler to spend the summer in eastern Massachusetts may be the border of a wooded swamp where tall elm and maple trees shade a dense undergrowth of ferns and other moisture-loving plants, a swamp which runs out toward drier ground where abounds a growth of gray birches or a tangle of raspberry canes, wild grapevines, and goldenrod. Such a spot furnishes countless situations for hiding the nest in the thick vegetation growing in the half-wet half-dry ground, and also a source of food near at hand in the high branches of the trees. Much the same conditions exist along the course of a brook winding through second growth, or near orchards or old neglected weedy pastures.
Sometimes, as William Brewster (1906) points out, the bird may frequent “dry hillsides covered with a young sprout growth of oak, hickory or maple.”
In a more southern latitude the habitat may be quite different. Maurice Brooks (1940), speaking of the bird in the central Allegheny Mountain region, says: “Shunning the swamps which it frequents in other portions of its range, it is highly characteristic of the ‘chestnut sprout’ association, where the males choose dead chestnuts for perches from which to sing. It is also fairly common in the pitch and scrub pine regions on the hills just back of the Ohio river, but becomes less common toward the eastern portion of the territory with which this paper deals. It ascends to at least 4,000 feet in Giles Co., Va.”
We can watch the little golden-winged warblers best, and often at very short range, when they are feeding their fledglings recently from the nest. The little birds sit quietly in the shrubbery near the ground, waiting for their parents. We can find them easily, for they frequently utter their characteristic “cricket note,” and we can approach them closely, for they scarcely heed us. The parents, too, when they are feeding the young birds, pay little attention to us and come fearlessly to them even when we stand near. At such times they work in a seeming panic of hurry, flying about in the low growth searching for food, or visiting the smallest branches high up in the trees, where they cling to the terminal twigs, hanging like chickadees as they probe among the curled up leaves (insect nests) for food hidden there, then back to the waiting young, seemingly in continuous motion and without the slightest pause in their nervous activity. At this season when the parents are busy with the young birds, about the third week in June in eastern Massachusetts, they are so occupied in searching for food that the male rarely sings.
In two particulars—their tameness, or indifference to our presence, and the almost complete cessation of singing thus early in the season—the goldenwing differs from the other common birds which breed in much the same regions, the chestnut-sided warbler, redstart, northern yellow-throat, ovenbird, and veery.
Jacobs (1904) speaks of the anxiety of the parent birds if the nest is disturbed when the nestlings are nearly ready to fly. He says: “If the hand is placed near the nest at this period of their growth, they will scramble out and flutter away, all giving vent to their chipping note, which brings down upon the intruder the wrath of both old birds, who fly close to his face, snapping their beaks and chipping loudly; then down upon the ground they fall and feign the broken wing act as long as one of the young continues to chirp.”
Voice.—The song of the golden-winged warbler is an inconspicuous little buzzing sound which one might pass by unnoticed, or hearing it for the first time, might ascribe it to a mechanical sound made by some insect, not suspecting it to be the song of a bird. Only after we have become thoroughly familiar with the song do we grasp its definite character, so that we can pick it out even when we hear it in the distance among a medley of other voices. In this particular it resembles the songs of Henslow’s and the grasshopper sparrows, which are scarcely audible, and pass unregarded until well known.