HERMIT WARBLER. Dendroica occidentalis (Townsend)

Field characters.—Half size of Junco. Cheeks always yellow; under parts whitish, unstreaked; back bluish or greenish gray; two light bars on each wing; tail white margined. Adult male: Whole head clear yellow except for black throat. (See pl. 9d). Female and immatures: Head dull yellow, crown mottled with blackish; little or no black on throat. Voice: Song of male three or four two-syllabled notes followed by two shorter ones, often with drawling intonation, zeekle, zeekle, zeekle, zeek, sup-sup; again, more clearly, ter'-ley, ter'-ley, ter'-ley, sic' sic'; call note a moderate tchip.

Occurrence.—Summer visitant in varying numbers to Transition and Canadian zones on west slope of Sierra Nevada. Recorded from Smith Creek (six miles east of Coulterville), Hazel Green, and near Chinquapin eastward to Merced Lake; common in Yosemite Valley. Transient in spring through western foothills (Legrange and Coulterville). Forages chiefly in coniferous trees 20 feet or more above ground, and nests in same locations. Solitary.

The name Hermit, applied to a warbler, might lead the novice to expect a bird of dull coloration and retiring habits. The first of these expectations will be dispelled by one glance at the bright yellow head, black throat, white under surface and dark back of the Hermit Warbler, while further acquaintance shows the bird to be a recluse only in the hiding of its nest.

The markings just alluded to will be sufficient to identify this warbler with certainty. (See pl. 9d). In the adult male the head is clear yellow, with a black throat patch; even female and young birds always show more or less yellow on the cheeks which stands out in contrast to the otherwise dark upper surface. The back, wings, and tail in the Hermit Warbler are dark like the same areas in the Black-throated Gray and Townsend warblers, and there are conspicuous white margins to the tail.

Hermit Warblers arrive in the Yosemite region before the end of April; singing males were already present in Yosemite Valley on April 28, 1916. Two individuals, in migration, were noted near Lagrange on May 7, 1919, and one near Coulterville, May 10, the same year. The species continues in the mountains until the latter part of August, two pairs being seen near Glacier Point on August 17, 1915, and one individual at 9000 feet altitude, a little east of Merced Lake, on August 26, 1915. None was noted east of the mountains at any time.

The population of this species varies somewhat from year to year; ordinarily the birds are not very common. We saw but limited numbers in 1915 and 1916. Yet in 1919, in Yosemite Valley and its immediate environs, the species was more abundant than either the Audubon or the Calaveras Warbler. In Yosemite Valley a 4-hour census on May 31, 1915, revealed about 6 singing males. The same number was recorded in a 5-hour census at Chinquapin, June 10, 1915, all the birds being below an altitude of 7000 feet. The population in 1919 at both these points was obviously larger.

The Hermit Warbler is a bird of the coniferous forests at middle altitudes. Pines and firs afford it suitable forage range and safe nesting sites. The birds keep fairly well up in the trees, most often at 20 to 50 feet from the ground. The Hermit may thus be found in close association with the Audubon Warbler, although the latter ranges to a much greater altitude in the mountains.

The song of the male Hermit Warbler, while varying somewhat with different individuals, is sufficiently distinct from that of the other warblers of the region to make possible identification by voice alone. This song is most nearly like that of the Audubon Warbler but usually not so clear or mellow. A male bird observed at Chinquapin seemed to say seezle, seezle, seezle, seezle, zeek, zeek; just that number of syllables, over and over again. The quality was slightly droning, but not so much so as that of the Black-throated Gray Warbler. Another song, clearer in quality, heard in Yosemite Valley, was written ter'-ley, ter'-ley, ter'-ley, sic', sic', thus much more nearly like the song of the Audubon Warbler. Other transcriptions ranged between these two as to timbre. A rendering set down at Glacier Point June 16, 1915, was as follows: ser-weez', ser-weez', ser-weez', ser', ser'. The marked rhythm throughout, and the stressed terminal syllables, are distinctive features of the Hermit's song. The call note is a moderate tchip, used by both sexes.

A Hermit Warbler watched in Yosemite Valley on June 22, 1915, by Miss Margaret W. Wythe (MS) was foraging in the upper parts of the trees and never came to the lower branches. Starting from near the trunk of a pine it would work out to the tip of one branch before going to another. Its demeanor while foraging was much more deliberate than that of any of the other warblers.

The only nest of the Hermit Warbler which came to our notice was discovered by Miss Wythe (MS) on June 28, 1915, in Yosemite Valley. She was following up some rather insistent chirping notes which came from a pine tree beside a road, when a young bird of this species, already fledged enough to be out of the nest, was seen. The yellow on its head was clearly in evidence, but the black chin spot was only beginning to show. The tail was only half an inch in length. The young bird, when first seen, had an insect in its bill, which it soon swallowed. Other similar notes were heard close by and soon the two parents were seen, one of which flew to the tree and evidently fed another member of the brood. Most of the time the birds remained in the outer portions of the trees, where the thick needle tufts screened them from view. Later the nest was located, 15 or 18 feet above the ground in what then proved to be plain view for an observer stationed below. The materials of which it was composed appeared gray in comparison with the green foliage of the pine.