Sp. Char. Above nearly pure dark olive-green; sides of the head ash-gray; the chin, throat, and under parts white; purest behind. Sides of throat and across the breast with arrow-shaped spots of dark plumbeous-brown. Sides of body and axillaries dull grayish-olivaceous. Tibiæ plumbeous; legs brown. Length, nearly 8 inches; wing, 4.20; tail, 3.20; tarsus, 1.15.
Hab. Eastern North America to shores of Arctic Ocean, and along northern coast from Labrador to Kodiak, breeding in immense numbers between the mouths of Mackenzie and Coppermine. West to Fort Yukon and Missouri River States. Winters south to Costa Rica. Chiriqui, Salvin; Cuba, Gundlach.
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.
The nests measure about 4 inches in diameter and 2¾ in height. The cavity is 2 inches deep, and its diameter 2½ inches. They are unusually compact for the nest of a thrush, and are composed chiefly of an elaborate interweaving of fine sedges, leaves, stems of the more delicate Equisetaceæ, dry grasses, strips of fine bark, and decayed leaves, the whole intermingled with the paniculated inflorescence of grasses. There is little or no lining other than these materials. These nests were all found, with but few exceptions, on the branches of low trees, from two to seven feet from the ground. In a few exceptional cases the nests were built on the ground.
Occasionally nests of this species are found constructed with the base and sides of solid mud, as with the common Robin (Turdus migratorius). In these, as also in some other cases, their nests are usually found on or near the ground. So far as I am aware neither its occasional position on the ground, nor its mud frames, are peculiarities ever noticeable in nests of T. swainsoni.
The eggs were usually four in number. Their color is either a deep green tint, or green slightly tinged with blue; and they are marked with spots of russet and yellowish-brown, varying both in size and frequency. Their mean length is .92 of an inch, and their mean breadth .64. The maximum length is .94 and the minimum .88 of an inch. There is apparently a constant variation from the eggs of the T. swainsoni; those of the aliciæ having a more distinctly blue ground color. The nests are also quite different in their appearance and style of structure. The Hypnum mosses, so marked a feature in the nests of T. swainsoni, as also in those of T. ustulatus, are wholly wanting in those of T. aliciæ.
This bird and the robin are the only species of our thrushes that cross the Arctic Circle to any distance, or reach the shore of the Arctic Ocean. It occurs from Labrador, all round the American coast, to the Aleutian Islands, everywhere bearing its specific character as indicated above. It is extremely abundant on and near the Arctic coast, between the mouth of the Mackenzie River and the Coppermine, more than 200 specimens (mostly with their eggs) having been sent thence to the Smithsonian Institution by Mr. MacFarlane. In all this number there was not a single bird that had any approach to the characters of T. swainsoni, as just given. From the Slave Lake region, on the other hand, T. swainsoni was received in nearly the same abundance, and unmixed during the breeding season with T. aliciæ.
Turdus swainsoni, Cab. Tschudi, Fauna Peruana, 1844-46, 188.—? Sclater & Salvin, Ibis, 1859, 6 (Guatemala).—Sclater, P. Z. S. 1858, 451 (Ecuador); 1859, 326.—Ib. Catal. 1861, 2, No. 11.—Baird, Birds N. Am. 1858, 216; Rev. Am. B., 1864, 19.—Gundlach, Cab. Jour. 1861, 324 (Cuba).—Ib. Repert. 1865, 229.—Pelzeln, Orn. Brazil. II. 1868, 92 (Marambitanas, Feb. and March).—Lawr. N. Y. Lyc. IX, 91 (Costa Rica).—Ridgway.—Maynard.—Samuels, 152.—Cooper, Birds Cal. 6.—Dall & Bannister. Turdus minor, Gmelin, Syst. Nat. I, 1788, 809 (in part). Turdus olivaceus, Giraud, Birds L. Island, 1843-44, 92 (not of Linn.). (?) Turdus minimus, Lafresnaye, Rev. Zoöl. 1848, 5.—Sclater, P. Z. S. 1854, 111.—Bryant, Pr. Bost. Soc. VII, 1860, 226 (Bogota).—Lawrence, Ann. N. Y. Lyc. 1863. (Birds Panama, IV, No. 384.)
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