HERMIT THRUSHES. Hylocichla guttata (Pallas)³⁹

Field characters.—Decidedly larger than Junco, but not so large as Russet-backed Thrush; bill short and slender. Upper surface plain brown, rufous tinged on tail; ring of buff around eye; wing with a concealed band of buffy, shown forth in flight; breast buffy with numerous triangular dark spots; sides grayish, not streaked; belly white. (See pl. 11c). Manner quiet; every few seconds, when bird is perched, the ends of the wings are spasmodically twitched and the tail is elevated and then slowly depressed. Voice: Song of male clear and musical, consisting of phrases uttered at varying intervals, each phrase of three to six 'words,' with the pitch of successive phrases now high, now low, etc.; usual call note a rather low soft sup.

Occurrence.—Common summer visitant on west slope of Sierra Nevada, chiefly in Canadian Zone; also spring transient near Mono Lake (subspecies sequoiensis). Fall visitant at all altitudes on west slope, and winter visitant there below level of heavy snow (subspecies guttata and nanus).³⁹ Keeps chiefly to wooded glades and ravine bottoms in summer; in winter affects sheltered situations generally, even chaparral. Solitary.

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³⁹Three closely similar subspecies of the Hermit Thrush have been found in the Yosemite region. These are so much alike that they probably cannot be distinguished in life; the Sierran race is the only one present in summer.

SIERRA HERMIT THRUSH, Hylocichla guttata sequoiensis (Belding), a relatively large sized, pale-colored subspecies (pl. 11c) which summers from the Cascade Mountains to southern California, was found by us from Hazel Green and Chinquapin eastward through Yosemite Valley to Washburn Lake and Tuolumne Meadows. It was already present at Hazel Green on May 13, 1919, and was recorded at Washburn Lake August 28, 1915; a single individual was collected at Ten Lakes, October 8, 1915. One was noted at Mono Lake Post Office on May 23, 1916.

ALASKA HERMIT THRUSH, Hylocichla guttata guttata (Pallas), a smaller race of medium-brown tone of color found in summer in southwestern and interior Alaska, is a common winter visitant on the west slope of the Yosemite region from Yosemite Valley westward to Pleasant Valley and Lagrange. The earliest definite record of arrival is for October 6, 1915, on Yosemite Creek at 7500 feet altitude.

DWARF HERMIT THRUSH, Hylocichla guttata nanus (Audubon), a smaller, dark-colored form whose summer range embraces the coast strip of southeastern Alaska, comes to the Yosemite region as a winter visitant in fair numbers. It has been recorded from Glen Aulin (October 4, 1915) westward to Sweetwater Creek at 3800 feet altitude.

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The Hermit Thrush, as a species, exhibits in extreme degree the unobtrusiveness of manner which characterizes many other members of the thrush family. It is garbed in plain colors of subdued tone, it has a sedate bearing, and save when singing its regular song is notably silent. The bird does not restrict itself to thick foliage as does the Varied Thrush and yet it does not forage out far beyond the cover of the vegetation in the way of the robin, choosing, rather, territory of intermediate nature. In summer the birds live in shaded glades amid coniferous trees or in sheltered cañon bottoms; in winter, when the species is more abundantly represented, the Hermits are found in similar places and also under the cover of chaparral on the hillsides.

Visitors in Yosemite Valley in some years have been fortunate in finding Hermit Thrushes settled fearlessly within the limits of one or more of the tent cities. Here the birds are seen most often at dusk, or, if at mid-day, where the shade is deepest, running along the narrow streets between the tents, just as they do, elsewhere, along the forest aisles.

In size the Hermit Thrush is about one-third the bulk of a robin. It is slightly smaller than the Russet-backed Thrush, but size alone will not serve readily to distinguish these two. (See pl. 11.) The Hermit has the upper side of the tail from its base strongly tinged with rufous, whereas the Russet-back is of the same brown color over the entire upper surface. Furthermore, the hermit thrush has a notable mannerism of twitching its wings spasmodically every few seconds, a movement often accompanied by a slow downward motion of the tail. These movements serve to identify the bird when it is in the shade where color features are of no avail.

The hermit thrush population of the Yosemite section is changed entirely each spring and fall. The birds which are present and nest in the region belong to a pale-toned subspecies designated as the Sierra Hermit Thrush. These arrive from the south and are already established by mid-May. Nesting begins soon afterward and the birds depart by the end of August. Then a short period ensues when there are few or no hermit thrushes in the region. By the latter part of September, birds which have nested in various parts of southern Alaska begin to arrive, to spend the winter here. In the fall the Dwarf and Alaska hermit thrushes, as the two races from the north are called, occur in considerable numbers at all altitudes below 9000 feet. The arrival of heavy snow forces most of those in the higher zones to below the 4000 or 3500 foot contour. Our records show the following examples of late tarrying at the higher altitudes. On the snowy morning of December 10, 1914, a hermit thrush was found in a dogwood thicket in Tenaya Cañon one-fourth of a mile above Mirror Lake; and on December 28 of the same year, 2 were seen at 5250 feet on the Big Oak Flat road near Gentrys. The latter were in thickets of the sticky-berried manzanita (Arctostaphylos mariposa).

The demeanor of the hermit thrush is quiet and deliberate. When foraging on the ground it acts in much the same manner as a robin, hopping several times in quick succession and then halting upright and immobile for a few seconds to scan the immediate vicinity before going forward again. There is this important difference, however: the hermit thrush seldom forages out in the open, and if it does it never goes far away from cover, to which it can flee in case of need. When foraging on shaded ground strewn with dead leaves its characteristic performance is to seize a leaf in its bill and throw it to one side with a very quick movement of the head, following this with an intent gaze at the spot uncovered. A thrush will flick over leaf after leaf in this manner, every now and then finding some insect which is swallowed, as is a berry, at one gulp. Hermit thrushes thus make use of a source of food not sought after by other birds; fox sparrows may forage over the same ground, but they are after seeds, which they get at by scratching. The thrushes do not use their feet at all for uncovering food. The thrushes' legs are relatively long, so that the birds stand high, and have consequently an increased scope of vision.

If a hermit thrush is come upon while not busy foraging, the bird will often stand quietly on its perch and watch the passer-by seemingly with wide-eyed curiosity. Close approach is often permitted, especially on dull days, though there is no reason to suppose that the thrush is less able to see well then than in bright sunlight. In fact the reverse may be true, for hermit thrushes are most conspicuously active at dusk. In this connection attention may be called to the fact that thrushes in general are big-eyed as compared with finches of equal bulk. (See fig. 59.)

Fig. 59. Heads of (a) Sierra Hermit Thrush and (b) Cassin Purple Finch, natural size, showing the relatively large eye of a shade-inhabiting bird (Thrush) as contrasted with that of a species which lives chiefly in the open (Purple Finch). Also the difference in bill is shown between an insect- and berry-feeding bird as contrasted with bud- and seed-eater.

Every kind of bird has some feature of exceptional interest to the bird student. With some species it is brilliancy of plumage, with others peculiarity of nesting habits. With the plainly-garbed and retiringly-disposed hermit thrush it is the bird's song which attracts and holds our interest. Few if any among the birds of the region excel the hermit thrush in impressiveness of song. The utterance is clear, highly musical and agreeable to our ears, not especially joyful but inducing in the human listener a pleasant reverie. Structurally, the song is varied, not at all monotonous as is that of the robin. It consists of phrases separated by rests of one to two seconds duration, each phrase consisting of three to six syllables. Successive phrases are pitched on different keys, one low, another high, a third midway of the bird's scale. Each begins with a clear full-toned whistled or flute-like syllable and ends with a tinkle, in quality suggesting an overtone. The notes of one bird listened to at Chinquapin were written: sur-wheel-yer-eel-yer; poor, aurelia-elia; seer, eetle-eetle; sir, wortle-ortle; per, wheetly-eetly, etc. When singing a thrush will sit motionless near the top of a small tree and may maintain its perch there for a long period of time, though not continually in voice. The song season lasts from some time in spring until early July, our latest record being of a bird's singing at Tuolumne Meadows on July 8 (1915).

The common call note is a soft chuck or sup, often doubled. It is not likely to be confused with the call note of the Russet-back. On rarer occasions, the hermit thrush gives a quite different, hoarse, not loud squall, tshee or kschee, somewhat like one call note of the Spurred Towhee but more metallic.

The hermit thrush usually places its nest not far above the ground in a small coniferous tree standing in some shaded spot. At Tuolumne Meadows on July 4, 1915, we found and visited repeatedly a nest which was 4-1/2 feet above the ground in one of a clump of young alpine hemlocks. There were three plain blue eggs. The bird which was doing the work of incubation was fairly tame, not quitting the nest until the observer was close at hand. She would fly a short distance away and then hop about on the ground. On July 13 the eggs were still unhatched, and as the nest was tilted and one egg had rolled out on the ground it was assumed that the parents had been frightened into deserting their home.

As already intimated, the hermit thrush does much of its foraging on the ground where during the summer it gets a variety of food including many insects. But in the winter season, like most members of the thrush family, it partakes to a large extent of berries. At El Portal in December one of these birds was seen feeding upon toyon berries as was another at Pleasant Valley. Other individuals were seen to take the sticky sweet berries of the manzanita (A. mariposa), and remains of several of these small fruits were found in the crop of a bird collected on Sweetwater Creek November 1, 1915.