He gives the measurements of 17 nests as follows: “Outside 3.6 to 5.0 inches in diameter, and 3.0 to 5.0 inches in depth; and on the inside, from 1.7 to 2.5 inches in diameter by 1.3 to 2.5 inches deep.” These measurements agree very closely with the records of several other observers. Jacobs continues: “Seemingly before the birds have had time to complete their nest, the female begins the deposition of the eggs. Generally, where I had opportunity to watch the nests daily, or at intervals between the beginning and completion of the set, the eggs were laid on consecutive days, but in two or three instances it was noticed that the laying missed a day.”
Eggs.—The set for the golden-winged warbler may consist of anywhere from 4 to 7 eggs; 5 is perhaps the commonest number, but 4 is a common number, and the larger numbers are increasingly rare. The eggs are ovate or short ovate, and have only a slight luster. They are white or creamy white, with a wide variety of markings in “auburn,” “argus brown,” “Mars brown,” “hazel,” “Hay’s brown,” “liver brown,” and “burnt umber,” with underlying speckles or spots of “light brownish drab” and “light vinaceous drab.” There is, also, much variation in the amount of markings, some being very sparingly speckled and others are quite heavily marked, with some of the spots assuming the proportions of blotches. Occasionally small hairline scrawls, or scattered spots, of brown so dark as to appear almost black, are found. The markings are usually denser toward the large end. The measurements of 50 eggs average 16.7 by 13.0 millimeters; the eggs showing the four extremes measure 18.6 by 13.0, 16.8 by 13.7, 15.5 by 12.5, and 15.9 by 12.3 millimeters (Harris).
Young.—Jacobs (1904) states that the incubation period is 10 days and that the young birds are able to leave the nest 10 days after hatching. In a nest which Maunsell S. Crosby (1912) watched closely, the eggs hatched on June 1 and the young flew on June 10.
The fledglings are delicate little birds, brownish olive on the back, washed with yellow below, and have two widely separated yellow wing bars. They have astonishingly long legs and soon become very active, fluttering about in the shrubbery and clinging to the branches. Walter Faxon (1911) in speaking of them gives this lively picture which could well be applied to them soon after leaving the nest: “In appearance and habit they were grotesque little fellows, clinging with their disproportionately long legs to the low herbage, like peeping Hylas in the springtime clinging to the grasses and weeds above the surface of the water. The little thread-like natal plumes still waving from the tips of their crown feathers enhanced the oddity of their appearance.” Mr. Faxon, to be exact, is speaking here of some young birds of mixed parentage, but his words apply equally well to the behavior and appearance 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.