The first nuptial plumage is acquired by a partial prenuptial molt, “which involves chiefly the anterior part of the head and the chin. A richer, half concealed, orange crown patch is acquired; the lores and adjacent parts become grayer, the anteorbital spot darker. Wear makes birds greener above and slightly yellower below. Young and old become practically indistinguishable.”
Subsequent molts consist of a complete postnuptial molt in summer and a partial prenuptial molt in early spring, as described above. The adult winter plumage “differs chiefly from first winter dress in possessing a larger, more distinct crown patch,” in the male, and more or less of it in the female. “The color below is uniform and paler.”
Food.—Nothing seems to be known about the summer food of the orange-crowned warbler, but it probably does not differ greatly from that of the lutescent warbler, whose food has been more thoroughly studied. In winter, it probably eats a fair proportion of berries and other fruits, especially when it spends the winter somewhat farther north than insects are to be found in abundance. It has also been known to come to a feeding station and eat suet, peanut butter, and doughnuts. In summer, it is probably almost wholly insectivorous. I can find no evidence that it does any damage to grapes or other cultivated fruits on its fall migration.
Voice.—Ernest Thompson Seton (1891) says of an orange-crowned warbler that he shot in Manitoba on May 12, 1883: “It was flitting about with great activity among the poplar catkins, and, from time to time, uttering a loud song like 'chip-e chip-e chip-e chip-e chip-e.' On May 141 shot another Orange-crowned Warbler. Its song is much like that of the Chipping Sparrow, but more musical and in a higher key. The bird is extremely restless and lively, moving about continually among the topmost twigs of the trees and uttering its little ditty about once in every half minute.”
Dr. Lynds Jones wrote to Dr. Chapman (1907): “The song is full and strong, not very high pitched, and ends abruptly on a rising scale. My note book renders it chee chee chee chw’ chw'. The first three syllables rapidly uttered, the last two more slowly. One heard late in the season sang more nearly like Mr. Thompson’s description: chip-e, chip-e, chip-e, chip-e, chip-e, but with the first vowel changed to e, thus eliminating what would appear to be a marked similarity to the song of Chippy. Even in this song the ending is retained.”
Francis H. Allen tells me that this warbler “has a chip note suggesting that of the tree sparrow but sharper.”
Field marks.—The orange-crowned warbler is a plain bird, with practically no white markings in wings or tail, clad in dusky olive-green, paler below, the underparts sometimes obscurely streaked with olive-gray. The brownish orange crown patch is usually not conspicuous, except in worn summer plumage, and lacking in young birds and some females.
Fall.—Orange-crowned warblers begin to leave northern Alaska in August. Dr. Nelson (1887) says that it is rare about St. Michael after the middle of the month, his latest date being August 24. The birds obtained at that season were mainly young of the year. “In fall this species frequents the vicinity of dwellings and native villages, where it searches the crevices of the fences and log houses for insects.”
The southeastward migration through central Canada and the United States seems to be leisurely and quite prolonged, mainly in September and early October, but often continuing into November. In Massachusetts, there are numerous late fall records and some winter records. Horace W. Wright (1917) has published an extensive paper on this subject and has collected the following Massachusetts records: “Mr. Brewster’s eleven records lie within the period of autumn from September 23 to November 28. There are three for September, namely, the 23rd and the 30th twice; none for October; and eight for November, namely, 7th, 9th, 10th, 17th, 20th-21st, 23rd-24th, 25th, and 28th. On two occasions two birds were present, November 9 and 28. My own records run later. The earliest is November 5, and the latest is January 23. They are November 5, 18, 20, 22, 28, 29, January 10, 19, 23.” As Mr. Wright’s records cover a period of 8 years ending with January 1916, they indicate that the orange-crowned warbler is not such a rare straggler in Massachusetts as is generally supposed, and may be looked for almost any year in late fall, or even winter. Mr. Forbush (1929) says of its occurrence there:
This warbler may be found almost anywhere in New England during the fall migration wherever there are trees and shrubbery. In my experience the bird has been either in the trees or in the tops of rather tall shrubs and never very high, but like other members of the genus, though it nests on the ground it is said to spend considerable time in the upper parts of trees. It seems fond of the edges of woodlands near water, but it also frequents open woods, orchards, fruit gardens and shade trees, where amid the foliage it is very seldom noticed by the ordinary observer. When approached it divides its attention between the observer and its insect prey, which it hunts assiduously in the manner of others of the genus. This warbler may be seen rarely in small companies, but more often singly or in company with a small group of warblers of other species.