Apparently there is a partial postjuvenal molt early in the summer, which is similar to that of other wood warblers. This produces the first winter plumages, in which the sexes are recognizable and much like the respective adults at that season. In the young male the upper parts are streaked with olive-green and black, the upper tail coverts are margined with olive-green and gray, and the white tips of the median wing coverts have narrow, black shaft streaks instead of the dusky wedges seen in the juvenal coverts. Ridgway (1902) says of the young female: “Similar to the adult female but pileum, hindneck, back, scapulars, rump, and upper tail-coverts plain olive-green, or with very indistinct narrow streaks of dusky on pileum and back; throat and chest pale grayish (the feathers dusky beneath surface), the former tinged with yellow anteriorly; sides and flanks indistinctly streaked with dusky.”
I have seen no specimens showing a prenuptial molt, which is probably finished before the birds arrive in Texas. The first and subsequent nuptial plumages may be largely produced by wear, as the fall and winter plumages are much like those of spring birds, but are concealed by the tips and margins of the feathers. However, it would be strange if there were no prenuptial molt, especially in young birds. Young birds in first nuptial plumage can be recognized by the worn and faded wings and tail.
Eggs.—Four eggs make up the regular set for the golden-cheeked warbler, although sometimes only three and very rarely five are found. They are ovate to short ovate and have only a very slight lustre. They are white or creamy white, finely speckled and spotted with “bay,” “auburn,” or “chestnut,” and occasionally “argus brown,” intermingled with spots of “vinaceous drab,” “brownish drab,” or “light mouse gray.” They are generally finely marked, but sometimes eggs will have spots which are large enough to be called blotches, or even a few small scrawls of very dark brown. The markings are concentrated at the large end, where frequently a fine wreath is formed, or the speckles may be so dense as to almost obscure the ground; occasionally the markings are scattered over the entire egg. The measurements of 50 eggs average 17.7 by 13.1 millimeters; the eggs showing the four extremes measure 18.9 by 13.0, 17.8 by 13.7, and 15.6 by 12.4 millimeters (Harris).
Young.—We have no information on incubation or on the care and feeding of the nestlings. Attwater (Chapman, 1907) has this to say:
The young birds out of the nest, which are being fed by the parents late in April and in May, are from early nests which have escaped destruction by “northers” on account of their sheltered positions and situations, and it is possible that then another nest is built and a second brood reared. * * * During June the family groups wander about together, chiefly in the cañons and along the lower hillsides, keeping together till the young are old enough to take care of themselves. While being fed by the parents the “twittering” of the young birds is continually heard, with the cautions “tick, tick” alarm notes of the female when enemies approach. Early in July they begin to scatter, as most of the young birds are then able to shift for themselves.
Food.—Very little has been mentioned regarding the food of this wood warbler beyond the fact that it seems to be mainly, if not wholly, insectivorous. Mr. Attwater (1892) says: “Upon examining the stomachs of a number of young birds which were being fed, I found they all contained (with other insects) a number of small black lice (Aphis sp.) which I watched the old birds collecting from the green cedar limbs.”
Behavior.—Mr. Attwater wrote to Dr. Chapman (1907):
Like most of the same sex of other Warblers, the female of this species is very shy, and seldom noticed except when an intruder disturbs the nest or when feeding the young after leaving it, but the male Golden-cheeked Warbler is by no means a shy bird. He keeps continually flying from tree to tree in search of insects, and on fine days uttering his song at short intervals from early dawn until after sundown, and before nest building begins shows little alarm upon being approached. I have stood under a tree a number of times within five or six feet of a wandering male Golden-cheek, which appeared as pleased and interested in watching me as I was in observing him. Seemingly he was desirous of assisting me to describe his song in my note-book, by very obligingly repeating it frequently for my special benefit.
Mr. Werner told Mr. Brewster (1879) that “their habits were similar to those of D. virens; they were very active, always on the alert for insects, examining almost every limb, and now and then darting after them while on the wing.”
Voice.—The song evidently bears a resemblance to that of the black-throated green warbler in quality. Mr. Werner wrote it tsrr weasy-weasy tweah, and referred to the notes as soft. Mr. Attwater wrote to Dr. Chapman (1907): “It would be difficult to describe the Golden-cheek’s song with any real satisfaction. It varies somewhat, being uttered much more rapidly by some individuals than by others. At a distance only the louder parts are heard, so that it sounds quite different than when heard at close quarters. The hurried song might be given as tweah, tweak, twee-sy, with some individuals introducing an extra note or two, and the slower or more deliberate style twee-ah, eseah, eachy. After the young leave the nests the males gradually stop singing, and at this period sometimes only use a part of the regular song.”