WHITE-CROWNED SPARROWS. Zonotrichia leucophrys (Forster)²⁷

Field characters.—Slightly larger than Junco (length about 7 inches). Sexes alike. Top and back of head with three white and four black stripes alternating, the middle stripe over the crown being white (pl. 8a, c); upper surface of body streaked with brown on a gray ground; tail plain brown; some small white spots forming two rows on wing; under surface of body grayish white, unstreaked. Immature birds have black and white on head replaced by reddish brown and dull buff, respectively. (See pl. 8b). Voice: Males have a clear set song; both sexes utter a sharp call or alarm note, peenk.

Occurrence.—Common summer visitant to Hudsonian Zone (subspecies leucophrys); common fall visitant to Transition Zone and winter visitant to Sonoran Zones on west side of Sierras, and fall and spring migrant east of the mountains in vicinity of Mono Lake (subspecies gambeli).²⁷

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²⁷Two subspecies of the White-crowned Sparrow occur in the Yosemite region, namely: (1) The HUDSONIAN WHITE-CROWNED SPARROW, Zonotrichia leucophrys leucophrys (Forster), which summers in the northeastern and mountainous parts of North America east of the Pacific humid coast strip, and which is distinguished principally by the small area between bill and eye (technically, the lores) being black (pl. 8a), is a summer visitant to the Hudsonian Zone of the Yosemite section of the Sierra Nevada. It was found established for the summer from near Mono Meadow and Porcupine Flat eastward to the vicinity of Williams Butte; it passes through the lower levels on both sides of the mountains during the spring migration. One case of nesting in Yosemite Valley has been reported (Dawson, 1916, p. 28). It arrives in Yosemite region by early May at least and departs about the end of September. It frequents willow thickets, in pairs or family parties.

(2) The INTERMEDIATE WHITE-CROWNED SPARROW, Zonotrichia leucophrys gambeli (Nuttall), which is found in summer in the interior of northwestern North America from British Columbia northward, and which is distinguished by having grayish white (instead of black) between bill and eye (pl. 8c) is a winter visitant in the lower zones (Sonoran) from Snelling and Lagrange eastward to El Portal; it also passes as a migrant, in fall and spring, along the east side of the Sierras in vicinity of Mono Lake, west to Walker Lake and Warren Fork of Leevining Creek, and is common in Yosemite Valley in the fall. It arrives in mid-September (September 17, 1915, near Williams Butte) and departs in late spring, remaining as late as May 6 (1919, at Lagrange). Frequents brush and small trees. Loosely flocking.

White-crowned sparrows may often be approached closely enough in the field for the observer to see whether the small area between bill and eye is black (leucophrys) or gray (gambeli). The two subspecies will not often be found on common ground, and any particular bird not closely seen may usually be guessed as to name by giving consideration to date and place of occurrence.

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White-crowned Sparrows occur somewhere in the Yosemite region at all times of the year, but the same individuals are not continuously in residence at any one place nor is the species to be found in any one locality at all seasons. As explained in footnote 27 there are two subspecies represented in the region. One of these, the Hudsonian White-crowned Sparrow, is the summer representative at the higher altitudes, while the other, the Intermediate White-crowned Sparrow, or Gambel Sparrow, is to be found in winter at the lower elevations to the west, and elsewhere in migration. The change, while involving considerable time during the spring and fall seasons of migration, is eventually complete, for none of the former race has been found in the region in winter nor do any of the latter remain there to nest in summer.

The earliest definite records of the arrival of the Hudsonian White-crown in the Yosemite region are for May 10 (1916) near Williams Butte and for May 8 (1917) at Smith Creek, east of Coulterville. Migration was still in progress on May 22 (1919), as a male bird in Yosemite Valley on that date tarried only a short time before moving on. The birds often establish themselves in the leafless willow thickets which border the streams in the boreal meadows before human invasion of those heights is easy. Hence, the first travelers of the season are apt to find the White-crowns already busy with nesting duties. Some individuals continue in their summer haunts until the end of September, several having been noted by us at Tuolumne Meadows on September 29, 1915, but none anywhere later than that date.

Our highest record for the Hudsonian White-crowned Sparrow was close to 11,000 feet altitude, in a patch of stunted willows in a draw between Mount Gibbs and Mount Dana, July 29, 1915.

The occurrence of the Intermediate Sparrow in the lower zones is practically complementary to that of its congener at the higher altitudes. Our earliest fall record for gambeli was made near Williams Butte on September 17, 1915. In Yosemite Valley the earliest date of its occurrence is September 18, 1917 (Mailliard, 1918, p. 18). Numbers were seen in the Valley on September 24, 1915. After mid-September the birds are to be met with commonly in the brush lands below 4500 feet. We think it likely that the Intermediate Sparrow does not winter in the vicinity of Mono Lake, although it is common there during the last half of September; probably it moves still farther south when the snow comes. On the west slope of the mountains some of the birds which arrive first appear in the Transition Zone, as in Yosemite Valley. Then, with or before the coming of the snow, they drop down to the foothill country where they remain throughout the winter and spring. They evidently do not move up the mountains again after the snow has gone but tarry at the lower levels until ready to depart directly to their nesting grounds in the north. On May 6, 1919, near Lagrange, about a dozen Intermediate Sparrows were seen and one was collected. The fact that some of the birds linger late in spring should not lead anyone into believing that this subspecies nests in California.

The two white-crowned sparrows may be readily distinguished in adult plumage from all other sparrows in the Yosemite region by the striping on their heads. Of the only two species which approach these birds in coloration the Golden-crowned Sparrow has a broad, golden-yellow patch on the middle of its crown and entirely lacks any pure white about its head, and the Lark Sparrow has at all ages, a brown-striped head. The latter has a conspicuously white-marked tail, as well.

White-crowned sparrows are thicket-dwelling birds at all seasons. (See pl. 18a and text fig. 21.) Often they may be seen on open level ground or grassland but never far from some hedge or bush to which they can resort if frightened. Their preference is for isolated or scattered shrubs rather than for broad areas of solid chaparral. When frightened they always seek shelter in brush instead of making off in the open, and when resting between periods of foraging they perch in the tops of thickets.

If a flock of White-crowns is come upon while it is foraging on the ground, the birds get up quickly and dart into the shelter of some nearby thicket, each pursuing a separate course. There they remain for a short time, silent and motionless, but peering furtively at the intruder. After a short period of quiet, if there be no further cause for fright, they become active again, giving voice to faint seeps and, individually, they begin to hop up in the brush where they can see about before venturing into the open again.

The general demeanor of the White-crown is almost sedate, just opposite to that of the Song Sparrow; every movement is made with seeming deliberation. As the White-crowns hop about on the ground they present a trim appearance, due in part to their long legs and manner of standing more nearly in an upright posture than most ground-feeding birds. Practically all of their foraging is done on the ground, but they do not habitually scratch like the heavier bodied and stouter clawed Fox Sparrows and towhees.

During the nesting season the White-crowns are in pairs, each pair occupying a separate and well-defined small area in the willows; but at other seasons they associate in loose flocks. This is true of the Hudsonian White-crowns in early fall before they migrate southward and of the Intermediate Sparrows throughout their stay in our latitude.

The song of the Hudsonian White-crowned Sparrow is a fairly loud clear lay, which carries well over the open meadows at the higher altitudes. The traveler may often hear a song long before getting close enough to see the performer. One transcription of the song, written in the field, is as follows: we chee äh weeeee äh; the last syllable is sometimes omitted. The theme is brief and unvaried. The White-crown, like several of its close relatives, occasionally sings at night. Both male and female utter a sharp call note, peenk, and this is repeated frequently when the birds are disturbed. At late dusk they are especially active in their favorite willow thickets and the call notes are given many times ere the birds settle down for the night. Seasonally the song is heard from the time the first migrants arrive up until early July. During the molting season they are quiet. By the end of August some have completed the renewal of their feathers, and songs of a more or less fragmentary character are given from then on until they depart southward for the winter.

The song of the Intermediate Sparrow may be heard in the foothills from time to time during the winter months, but it is then often incomplete. While to the trained ear distinct, it resembles that of the Hudsonian White-crown so much that a person having heard either one readily recognizes the song of the other as that of a closely related bird.

Nests of the Hudsonian White-crown are not difficult to locate, for the birds are quick to set up a disturbance whenever their home sites are approached. On June 25, 1916, at the Farrington Ranch near Mono Lake a nest with 4 eggs was discovered, sunk even with the surface of the ground beneath a willow bush in a meadow. It was made of rootlets and grass, with a lining of black horsehair. Outside, the diameter was about 4 inches and the height (after removal of the nest), 2-1/4 inches; while inside the diameter was 2-1/4 inches and the depth at the center about 1-3/4 inches. The 4 eggs were well advanced in incubation. At Tuolumne Meadows on July 5, 1915, a nest was found 12 inches above the ground in a willow shrub close to the river bank. It contained three young birds about half grown, and the parents evinced great solicitude during our examination of the nest. A week later these young had left the nest but were evidently still in the vicinity, for whenever we approached the place the old birds exhibited marked concern.

The juvenal Hudsonian White-crowned Sparrows wear a much more streaked pattern of coloration than their parents, the breast as well as the whole upper surface bearing a pattern of narrow streaks. This plumage is worn but a short time. In August all of it (except the wing and tail feathers) is molted, and the bird then acquires the immature or first winter plumage, which resembles that of the adult save for the coloration of the crown, which is brown and buff instead of black and white. In this plumage the immature birds go south to spend the winter, but before they return, another partial molt in early spring gives them the crown coloration of the adults.

When the Intermediate Sparrows come south in the fall the immature birds have dull colored heads, but at the end of winter, in March or April, the prenuptial molt gives them black-and-white striped heads like their parents. This spring molt is participated in by both adults and immatures, but, obviously, the change in color is conspicuous only in the latter.

The stomach of an adult male Hudsonian White-crowned Sparrow taken at Lake Tenaya on July 3, 1915, contained, in so far as its contents were recognizable, nothing but beetles. General observation leads to the belief that a considerable part of this sparrow's food during the summer consists of insects. The birds which winter in the foothills (gambeli) subsist largely if not entirely on vegetable material (the cotyledons of newly sprouting plants, and seeds) most of which is gleaned from the open ground near thickets. At Lagrange they take advantage of easy forage obtained in the gardens, and in so doing conflict with the interests of the truck gardeners there.