The male in this plumage may usually be distinguished from the female
by possessing a trace, or a distinct stripe, of chestnut on the flanks, the young female at least lacking it.
Habits. The geographical distribution of this common species during its season of reproduction is inferred rather than positively known. So far as I am aware, it is not known to breed farther south than Massachusetts. Yet it is probable that, when we know its history more exactly, it will be found during the breeding-season in different suitable localities from Pennsylvania to Canada. Mr. H. W. Parker, of Grinnell, Iowa, mentions this bird as common in that neighborhood.
Until recently it was regarded as a rather rare species, and to a large extent it had escaped the notice of our older ornithological writers. Wilson could give but little account of its habits. It passed rapidly by him in its spring migrations. He did not regard it as common, presumed that it has no song, and nearly all that he says in regard to it is conjectural. Mr. Audubon met with this species but once, and knew nothing as to its habits or distribution. Mr. Nuttall, who observed it in Massachusetts, where it is now known to be not uncommon in certain localities, also regarded it as very rare. His account of it is somewhat hypothetical and inexact. Its song he very accurately describes as similar to that of the D. æstiva, only less of a whistle and somewhat louder. He represents it as expressed by tsh-tsh-tsh-tshyia, given at intervals of half a minute, and often answered by its mate from her nest. Its lay is characterized as simple and lively. Late in June, 1831, he observed a pair collecting food for their young on the margin of the Fresh Pond swamps in Cambridge.
Mr. Allen has found this species quite common in Western Massachusetts, arriving there about the 9th of May, and remaining through the summer to breed. He states—and his observations in this respect correspond with my own—that during the breeding-season they frequent low woods and swampy thickets, nesting in bushes, and adds that they are rarely found among high trees. They leave there early in September.
Professor Verrill found this Warbler a common summer visitant in Western Maine, arriving about the second week in May, and remaining there to breed. Mr. Boardman thinks it reaches Eastern Maine about the middle of May, and is a common summer resident. I did not meet this species either in New Brunswick or Nova Scotia, nor was Dr. Bryant more fortunate, but Lieutenant Bland gives it in his manuscript list of the birds found in the neighborhood of Halifax.
Mr. Ridgway informs me that this species breeds in the oak openings and among the prairie thickets of Southern Illinois.
During the eight months that are not included in their season of reproduction, this species is scattered over a wide extent of territory. Their earliest appearance in the Northern States (at Plattesmouth) is April 26, and they all disappear early in September. At other times they have been met with in the Bahamas, in Mexico, Guatemala, Costa Rica, and Panama. It has
not yet been detected in the West Indies. M. Boucard obtained specimens at Playa Vicente, in the hot country of Oaxaca, Mexico.
In the neighborhood of Calais, Mr. Boardman informs me that this Warbler is common, and that its habits resemble those of the Black-poll Warbler more than those of any other of the genus. It always nests in bushes or in low trees, and in the vicinity of swamps.