As originally described, this species differs from swainsoni in larger size, longer bill, feet, and wings especially, straighter and narrower bill. The back is of a greener olive. The breast and sides of the head are entirely destitute of the buff tinge, or at best this is very faintly indicated on the upper part of the breast. The most characteristic features are seen on the side of the head. Here there is no indication whatever of the light line from nostril to eye, and scarcely any of a light ring round the eye,—the whole region being grayish-olive, relieved slightly by whitish shaft-streaks on the ear-coverts. The sides of body, axillars, and tibiæ are olivaceous-gray, without any of the fulvous tinge seen in swainsoni. The bill measures .40 from tip to nostril, sometimes more; tarsi, 1.21;
wing, 4.20; tail, 3.10,—total, about 7.50. Some specimens slightly exceed these dimensions; few, if any, fall short of them.
In autumn the upper surface is somewhat different from that in spring, being less grayish, and with a tinge of rich sepia or snuff-brown, this becoming gradually more appreciable on the tail.
A specimen from Costa Rica is undistinguishable from typical examples from the Eastern United States.
Habits. This species, first described in the ninth volume of the Pacific Railroad Surveys, bears so strong a resemblance to the Olive-backed Thrush (T. swainsoni), that its value as a species has often been disputed. It was first met with in Illinois. Since then numerous specimens have been obtained from the District of Columbia, from Labrador, and the lower Mackenzie River. In the latter regions it was found breeding abundantly. It was also found in large numbers on the Anderson River, but was rare on the Yukon, as well as at Great Slave Lake, occurring there only as a bird of passage to or from more northern breeding-grounds.
In regard to its general habits but little is known. Dr. Coues, who found it in Labrador, breeding abundantly, speaks of meeting with a family of these birds in a deep and thickly wooded ravine. The young were just about to fly. The parents evinced the greatest anxiety for the safety of their brood, endeavoring to lead him from their vicinity by fluttering from bush to bush, constantly uttering a melancholy pheugh, in low whistling tone. He mentions that all he saw uttered precisely the same note, and were very timid, darting into the most impenetrable thickets.
This thrush is a regular visitant to Massachusetts, both in its spring and in its fall migration. It arrives from about the first to the middle of May, and apparently remains about a week. It passes south about the first of October. Occasionally it appears and is present in Massachusetts at the same time with the Turdus swainsoni. From this species I hold it to be unquestionably distinct, and in this opinion I am confirmed by the observations of two very careful and reliable ornithologists, Mr. William Brewster of Cambridge, one of our most promising young naturalists, and Mr. George O. Welch of Lynn, whose experience and observations in the field are unsurpassed. They inform me that there are observable between these two forms certain well-marked and constant differences, that never fail to indicate their distinctness with even greater precision than the constant though less marked differences in their plumage.
The Turdus aliciæ comes a few days the earlier, and is often in full song when the T. swainsoni is silent. The song of the former is not only totally different from that of the latter, but also from that of all our other Wood Thrushes. It most resembles the song of T. pallasi, but differs in being its exact inverse, for whereas the latter begins with its lowest notes and proceeds on an ascending scale, the former begins with its highest, and concludes with its lowest note. The song of the T. swainsoni,
on the other hand, exhibits much less variation in the scale, all the notes being of nearly the same altitude.
I am also informed that while the T. swainsoni is far from being a timid species, but may be easily approached, and while it seems almost invariably to prefer the edges of the pine woods, and is rarely observed in open grounds or among the bare deciduous trees, the habits of the T. aliciæ are the exact reverse in these respects. It is not to be found in similar situations, but almost always frequents copses of hard wood, searching for its food among their fallen leaves. It is extremely timid and difficult to approach. As it stands or as it moves upon the ground, it has a peculiar erectness of bearing which at once indicates its true specific character so unmistakably that any one once familiar with its appearance can never mistake it for T. swainsoni nor for any other bird.