PINE SISKIN. Spinus pinus pinus (Wilson)

Field characters—About half size of Junco; size and general habits of a goldfinch. Sexes practically alike. Tail deeply notched at end (fig. 53d). Whole body plumage both above and below, streaked brown and dull white; middle of wing and whole base of tail canary yellow, these areas of bright color showing best as birds take flight. Flight undulating to marked degree. Voice: A plaintive call note, swe-ah', with rising inflection; also a throaty 'watch-winding' note, zwe-e-e-e-et or zree-e-e-e-eet, the inflection rising and the intensity increasing until the call is ended abruptly; in summer there is also a goldfinch-like song.

Occurrence.—Common in spring, summer, and fall in Transition, Canadian, and Hudsonian zones west of Sierran crest; recorded from Hazel Green eastward to Tioga Pass. In winter small numbers are found in the Sonoran zones, as at Snelling. Present in Yosemite Valley at least from April to December. Frequents both coniferous and deciduous trees, and also often forages about meadows on flower heads close to or on ground. Usually in flocks.

In general characteristics the Pine Siskin is very much like the goldfinches, but it does not wear so bright a pattern of plumage, at least as regards the male sex. Indeed, its dully streaked pattern recalls more the coloration of some kind of ground-dwelling sparrow. Only by a yellow bar on the wing and by yellow at the base of the tail (fig. 53d), which markings are partially concealed, does its coloration suggest kinship with the more brilliantly marked birds.

In the forested region on the west slope of the Sierra Nevada from Hazel Green, Chinquapin, and Yosemite Valley east to the crest line of the mountains, Pine Siskins are relatively common from early spring to late fall. Our earliest seasonal record for the species in Yosemite Valley is for April 30 (1916) and the latest, made on the margin of the Valley, at Fort Monroe, is for November 26 (1914). In January a few were noted at Snelling. We saw none east of the Sierran crest at any time nor were any observed in the Yosemite Valley or its environs during the season of heavy snow. It remains to be determined whether any of the siskin population stays in the higher altitudes throughout the winter. The numbers which occur at the lower levels to the west in that season are relatively small, and some of the birds may go entirely out of the mountains, wintering still farther west or to the southward.

The general behavior of Pine Siskins is much like that of the goldfinches. The siskin is, perhaps, more persistently flocking in habit. The flocks vary in size from a half-dozen to a half-hundred or even more individuals. In flight each member of the band rises and falls independently of its companions yet the flock formation in this species is usually more compact than is that of the goldfinches. The flight course of a flock is apt to be roundabout or circling, both when the birds are leaving and arriving at a perch. Sometimes when stirred up they will fly around in a wide circle several times and then settle down again practically in the place whence they arose; and this same repeated circling is apt to occur when they arrive from a distance and are settling down preparatory to foraging in some particular spot.

At times a flock of siskins will act as if greatly perturbed, and fly about seemingly without definite purpose. The flock will alight in one tree only to leave precipitately a few seconds later and make off in a circling course to some other temporary resting place. Such a performance is usually accompanied by frequent utterances of the gasping 'watch-winding' note. When actively foraging, the individuals perch every which way, some upside down like chickadees. Often a large feeding flock will be perfectly quiet save for the patter of falling bud scales or seed hulls.

The Pine Siskin subsists upon a somewhat different class of food than its goldfinch relatives. Its usual diet comprises tree buds of various kinds, material from seed cones and catkins of alders and willows, and tender young needle tips from coniferous trees. Some of the siskins seen at Fort Monroe on November 26, 1914, were feeding on buds in the black oaks, while others were searching for seeds in the little cones of the Douglas spruces. At Tuolumne Meadows on July 5, 1915, the birds were feeding in the terminal foliage of lodgepole pines and an adult bird taken had its crop filled with needle buds of that tree. A certain amount of the foraging of siskins is done on the ground in openings between forest trees, or in meadows, where ripening seeds of plants of the sunflower tribe are diligently sought after.

We obtained only one suggestion as to the nesting activities of the Pine Siskin. At Tuolumne Meadows on July 6, 1915, a young bird, not able to fly, was picked up from the ground. It had evidently fallen from a nest somewhere in the lodgepole pines near by.