Sp. Char. (No. 37,011.) Whole upper parts and sides of head uniform plumbeous; the lower part of the back with a faint wash of olivaceous. A white line from bill to and around eye; a dusky line from corner of eye to bill. Sides of breast and flanks plumbeous, paler than the back; the flanks very slightly tinged with olive-green. Rest of under parts white; the axillars ashy, edged with white. Wings above with two conspicuous white bands; the innermost quills edged externally and the longer ones internally with white, the latter edged externally with light ash. Bill and legs dark plumbeous, “Iris hazel.” Tail-feathers narrowly edged all round with white, narrowest internally, and increasing from central to lateral feathers. Upper tail-coverts clear ash.
Vireosylvia plumbea.
37010
As the specimen in finest plumage (described above) is moulting the quills, the measurements are taken from another (37,010). In this the first quill is not quite one third the second, which equals the sixth, the third and fourth longest.
(No. 37,010.) Fresh specimen: Total length, 6.10; expanse of wings, 10.80. Prepared specimen: Total length, 5.75; wing, 3.25; tail, 2.70; difference between tenth and longest quill, .95; exposed portion of first primary, .75, of second, 2.34, of longest,
third (measured from exposed base of first primary), 2.54; length of bill from forehead, .55, from nostril, .31, along gape, .70; tarsus, .75; middle toe and claw, .60, claw alone, .21; hind toe and claw, .50, claw alone, .23.
Hab. Southern Rocky Mountains; East Humboldt Mountains, Nevada (Ridgway). In winter to Colima, Mexico.
While the pattern of coloration is precisely similar to that of Lanivireo solitarius, the difference in the colors appears to be occasioned merely by removing, as it were, the yellow stain, which on the plumbeous produces the olive-green tinge, and exists in a purer tint along the sides, leaving, essentially, only clear plumbeous and pure white; there is, however, in the most typical specimens, always a faint tinge of green on the rump, and a stain of yellow along the side. Though identical with solitarius in most of its proportions, the wings and tail are considerably longer than in the average of that form.
There are many specimens from the Rocky Mountains and westward that are so decidedly intermediate between solitarius and plumbeus, that, considering also the lack of essential difference in form and coloration between the two, we do not hesitate to consider them, along with cassini and propinquus (see [page 373]), as races of a single species, of which each is the representative in a particular region. Thus, V. solitarius breeds in the Eastern Province of the United States (and possibly in the Western, following the same route far to the northward that many Eastern birds pursue in straggling westward), and migrates in winter into Middle America as far as Guatemala; those which breed in the Northwest pass directly southward, thus crossing the region where cassini and plumbeus breed, which accounts for their being obtained together. V. cassini is the representative on the opposite side of the continent; but the history of its migrations is yet obscure. V. plumbeus is the Middle Province and Rocky Mountain representative, breeding alone in that region, and in winter migrating southward through Western Mexico as far as Colima. V. propinquus is another permanent race, but a local one, being resident in the country where found, though mixed in winter with visitors of solitarius from the North.
Habits. Of this very recently discovered race, very little is at present known. It was first described by Dr. Coues, who met with it in Arizona, near Fort Whipple. He says it is especially abundant in the northern part of that Territory. It was by far the most common Vireo at Fort Whipple, where it is a summer resident, arriving there about the 15th of April and remaining until October.