At Glacier, nest-building averaged to commence about the 25th of May, and the first eggs were found on the 1st of June. The last set was found July 15th. All nests examined in the earlier part of the season contained four eggs; those found later, presumably second efforts, never had more than three.
As a curious example of the use of the imagination on the part of early writers, take this from our venerated Cooper[36]: “The eggs, unlike those of most thrushes, are white, spotted thickly with brown, and four or five in number.” The brown spotting is all right and an unpigmented shell is not an impossibility, but deviations from the characteristic greenish blue of the ground-color have not since been reported.
No. 94.
OLIVE-BACKED THRUSH.
A. O. U. No. 758 a. Hylocichla ustulata swainsonii (Cab.).
Synonyms.—Swainson’s Thrush. Eastern Olive-back. Alma’s Thrush (H. u. almæ Oberh., disallowed by A. O. U. Com.).
Description.—Adults: Similar to H. ustulata but grayer and more olivaceous; “color of upperparts varying from olive to grayish hair brown in summer, from deep olive to slightly brownish olive in winter”; ground color of underparts lighter buffy (yellowish buff or creamy buff); sides and flanks grayish—instead of brownish-olive. Size of last.
Recognition Marks.—As in preceding; grayer above, lighter buffy below.
Nesting.—Nest and Eggs indistinguishable from those of typical form, H. ustulata.
General Range.—North America in general except Pacific coast district south of Cross Sound and Lynn Canal; breeding from the mountainous districts of the United States (especially northerly) north to limit of trees; south in winter thruout Mexico and Central America to Peru, Bolivia, etc.
Range in Washington.—Imperfectly made out as regards that of H. ustulata. Found breeding in the valley of the Stehekin hence presumably summer resident in timbered districts of eastern Washington.
Authorities.—Bowles and Dawson, Auk, Vol. XXV. Oct. 1908, p. 483.
Specimens.—Prov. B.
The more open woods and more abundant suns of eastern Washington effect that reduction of color in the “burnt” Thrush, which henceforth characterizes the species clear thru to the Atlantic. It would be idle to trace in detail all accompanying changes of manner and habit, but we can hardly fail to note the improved quality of the Olive-back’s song. This is most nearly comparable to that of the Willow Thrush and has something of the same rolling vibrant quality. It is, however, less prolonged and less vehement. It may or may not retain the liquid l’s, but it discards outright the rich r’s, which the Veery rolls under his tongue like sweet morsels; and the pitch of the whole rises slightly, perhaps a musical third, as the volume of sound diminishes toward the end: We-e-o, we-e-o, we-o we-o weee. A song heard some years ago at the head of Lake Chelan, weeloo weeloo weelooee looee, seemed to have all the music of perfected swainsonii in it, yet it was not till the season of 1908 that Mr. Bowles established the fact of the Olive-back’s presence and the Russet-back’s absence from the Stehekin Valley. On the other hand, Ridgway finds that both forms sometimes occur together, even during the breeding season; so we are not yet prepared to make generalizations as to the relative distribution of these birds in Washington.
No. 95.
ALASKA HERMIT THRUSH.
A. O. U. No. 759. Hylocichla guttata (Pallas).
Synonym.—Kadiak Dwarf Thrush (Ridgw.).
Description.—Adult: Upperparts plain grayish brown (hair brown to near broccoli brown) changing on rumps to dull cinnamon-brown of upper tail-coverts and tail; a prominent whitish orbital ring; sides of head mingled grayish brown and dull whitish; underparts dull white, clear only on belly,—throat and breast tinged with pale creamy buff; sides and flanks washed with pale grayish brown; throat in confluent chain on side and lower throat, chest and upper breast—spotted with dusky or sooty, the spots narrow and wedge-shaped on lower throat, broadening and deepening on chest, fading and becoming rounded on breast. Bill drab brown paling on mandible basally; feet and legs brown; iris dark brown. Winter specimens are brighter and more strongly colored thruout. Young birds are streaked with buffy above and the spotting of underparts inclines to bars on breast and sides. Length 6.30-7.40 (160-188); wing 3.46 (88); tail 2.52 (64); bill .50 (12.7); tarsus 1.14 (29).
Recognition Marks.—Sparrow size; cinnamon of tail (and upper-coverts) contrasting more or less with duller brown of remaining upperparts.
Nesting.—Does not breed in Washington. Nest and Eggs as in H. g. sequoiensis.
General Range.—Coast district of Alaska breeding northward and westward from Cross Sound; southward in winter as far as Texas and western Mexico, migrating chiefly coastwise.
Range in Washington.—Spring and fall migrant west of the Cascades.
Migrations.—Spring: Tacoma, April 15, 1905 (J. H. Bowles). Fall: Seattle Sept. 21, 1907 (Jennie V. Getty).
Authorities.—Bowles and Dawson, Auk, XXV. Oct. 1908, p. 483.
Specimens.—P(Alaskan). Prov. B.
About all we can certify to, so far, is that there are two varieties of the Hermit Thrush which may be seen on Puget Sound during the migrations: a lighter and grayer form, presumably from northwestern Alaska; and a darker, more warmly-tinted bird, H. g. nana, which may or may not summer to some extent in western Washington. Specimens so far encountered in eastern Washington are probably H. g. sequoiensis, en route to or from their breeding haunts in the high Cascades; while if any are ever captured in the mountains of Stevens County, they will probably prove to be of the H. g. auduboni type, which prevails in the eastern portion of British Columbia.
No. 96.
SIERRA HERMIT THRUSH.
A. O. U. No. 759 part. Hylocichla guttata sequoiensis (Belding).
Synonyms.—Western Hermit Thrush. Cascade Hermit Thrush. Mountain Hermit.
Description.—Similar in coloration to H. guttata but larger, paler and grayer. Adult male: wing 3.65 (92.8); tail 2.83 (71.8); bill .53 (13.5); tarsus 1.12 (28.4).
Recognition Marks.—As in H. guttata.
Nesting.—Nest: of bark-strips, grasses, leaves and moss, lined with fine rootlets, placed on ground in thickets or at moderate heights in fir trees. Eggs: 3 or 4, greenish blue unmarked—not certainly distinguishable from those of the Willow Thrush. Av. size, .85 × .65 (21.6 × 16.5). Season: June, July; one brood.
General Range.—Mountains of the Cascade-Sierra system and from Mt. Whitney north thru central British Columbia, etc., to the Yukon River; south in winter to Lower California, Sonora, etc.
Range in Washington.—Common summer resident in the Cascade Mountains—further distinction undetermined.
Authorities.—Dawson, Auk, Vol. XXV. Oct. 1908, p. 483.
Specimens.—D.