CLARK NUTCRACKER. Nucifraga columbiana (Wilson)

Field characters.—Decidedly larger than Robin or Blue-fronted Jay, but not so big as Crow. Body plumage light gray; wing black, with large white patch at hind margin; tail white with central feathers black. Habits largely crow-like. Voice: A nasal cawing note, kayr, more or less prolonged, and repeated at irregular intervals.

Occurrence.—Common resident of Hudsonian Zone on crest and upper slopes of Sierra Nevada. Ranges down locally in certain seasons through Canadian Zone to upper portion of Transition Zone, and up above timber line into Arctic-Alpine Zone. Recorded in summer from 9000-foot ridge between basins of Cascade and Yosemite creeks, and from ridge near Ostrander Rocks, eastward to Warren Peak and vicinity of Walker Lake; also on Mono Craters. Observed in mid-August and September at Glacier Point, in October at head of Yosemite Falls, and in December near Gentrys and near Merced Grove Big Trees. Frequents tops of trees at margin of forest, around meadows, and at timber line. Non-flocking yet socially inclined.

The bleak upper altitudes of the Yosemite region with their sparse stands of trees and their broad expanses of bare granite suggest strongly the rigorous climate to which the high country is subjected during the long winter season. Despite this forbidding aspect, a rather large permanent animal population is able to maintain itself there through the year. Among the birds in this group of hardy mountaineers none is more conspicuous than the Clark Nutcracker.

Rarely does the book name of a bird fit so well as in the case of the Clark Nutcracker. The first word of the name makes record of the discoverer of the bird, the earliest United States Government explorer in the far west, Captain William Clark (in some current literature spelled Clarke), one of the principals in the famous Lewis and Clark Expedition across the Rocky Mountains in 1805-1806. And the word nutcracker applies excellently to the food-getting habits of the bird. The name Clark Crow has also been used in referring to the species; and some people in the mountains call the bird the Fremont Crow, thus connecting its name with that of another though later explorer who actually reached the mountains of California.

Although the Clark Nutcracker is a characteristic resident of the Hudsonian Zone, it strays both above and below this belt. In summer, after the broods of the year are fledged, some of the birds move down the mountains. For instance, they appear at Glacier Point in August where they are not ordinarily seen or heard earlier. And at the same season they sometimes wander up over the rock-strewn ridge crests well above timber line. Some of the nutcrackers which stray to the lower altitudes remain there at least until early winter, as the species has been observed about the top of Yosemite Falls in October, and near Gentrys and Merced Grove Big Trees in December. But most of the birds remain at the normal high altitudes through the winter months.

The bird's conspicuously pied plumage, set forth best when in flight, its far-carrying nasal call notes, and its marked preference for the tops of trees bordering on a clearing, all serve to bring the species to the attention of everyone who traverses its domain.

In coloration and habits the Clark Nutcracker cannot be confused with any other bird in the whole Yosemite avifauna. The adults and young, both sexes, are all practically alike. The body is pale gray; the wings are black, each with a large white patch on the hind margin (technically speaking, on the tips of the secondary wing feathers); and the tail is black centrally and broadly pure white on each side. The 'face,' or area around bill and eyes, is whitish in adults, but this can be seen only at close range. In the fresh plumage, which is acquired by a complete molt in July or early August, earlier than in most birds, the body coloration is clear light gray. This color, however, quickly becomes soiled by contact with pitch. The bird's daily round of foraging after seeds in cones either in the trees or on the ground beneath soon results in its plumage acquiring a brownish overtone, and this becomes deeper as the winter comes on. In early summer, before the molt, the old birds present a decidedly bedraggled appearance, the feathers on the top of the head and the back being, in some individuals, literally worn to shreds.

In bodily configuration the Clark Nutcracker shows stout build; its wings are proportionately longer than those of blue jays, and its tail is shorter. These features may be related directly to its life in more open situations. The bill is long, thick at base, tapering to a pointed tip (fig. 49). The bill of the nutcracker thus resembles in form that of the Piñon Jay rather than that of any of the true blue jays.

The nesting season of the Clark Nutcracker commences so early in the spring that few naturalists anywhere, and none in California so far as we know, have seen the eggs of the species. Such information as we have been able to assemble on this matter for the Yosemite region is rather meager and of an indirect nature. The 'evidence' is as follows. Near Williams Butte on April 30, 1916, a pair of adult nutcrackers was seen foraging in some willows, and near Walker Lake on May 9 of that year another pair was encountered. In each case the headquarters of the birds were likely on the higher east face of the Sierras close by. During a visit to the upper margin of the forest on Mono Craters on June 10, 1916, at least four family parties all containing fully fledged young were observed. The young birds were following their parents about and begging assiduously for food. Whether or not these families were reared in the immediate vicinity is problematical. Adult birds collected in Lyell Cañon in mid-July showed by dissection that the breeding season was long passed. It may be safely inferred that the pairs of adults seen by themselves in April and early May had eggs or young, more likely the latter. All of this evidence points to nest building as beginning in the Yosemite region in March or early April.

Fig. 49. Head of Clark Nutcracker, showing protecting "mask" of feathers which serves to keep snow and other foreign materials out of nostrils. Natural size.

The staple article of diet of the Clark Nutcracker seems to be pine nuts. An adult female shot on Williams Butte, September 22, 1915, held in its throat 72 ripe seeds of the piñon, comprising a volume of about one cubic inch. Another female taken September 25 of the same year on Warren Fork of Leevining Creek held in her distended throat 65 mature seeds of the white-bark pine, and some fragments, all together weighing 10 grams or close to 7 per cent of the weight of the bird, which was 146 grams. The nutcrackers on the east side of the mountains often descend to the slopes where piñons are abundant, and the nuts of that tree are known to be a favorite food in many localities elsewhere in its range. During at least a part of the year, however, this vegetarian diet is varied by the birds turning their attention to insects or other forms of animal life. Sometimes they behave as though actually fly-catching. Taking position at the top of a tree, preferably one with dead bare branches at the top, a nutcracker will dart out on the wing as if after passing insects. In Lyell Cañon on July 16, 1915, several of the birds were engaged in this manner. Occasionally one would fly out a hundred feet or more, pursuing an erratic course before finally returning to its perch.

The lusty calls of the Clark Nutcracker are to be heard early and late. The notes have a certain nasal intonation which makes them unmistakable when once the naturalist has heard them. The pleading calls of the young are distinctly different in quality from the notes of the adult birds. During the fall months, when the social tendency of the species is most manifest, a great deal of cawing is indulged in. Feeding and calling may go on without mutual interference. In one instance a bird which had been calling loudly was shot and its throat was found to be distended with a large mass of pine seeds. Nutcrackers, like crows, are apt to sound an alarm when a hawk passes near them. Thus at Vogelsang Lake on August 30, 1915, when a Red-tailed Hawk flew close by our camp a party of nutcrackers in the vicinity set up a great outcry.

Mr. Gabriel Souvelewsky told us that, a number of years ago while climbing about the rocky summits above Vogelsang Lake, he came upon a roosting place of some Clark Nutcrackers. There were about three dozen of the birds in a loose company and the droppings on the rocks indicated that the place had been resorted to for some time as a sort of meeting ground.

Although they are at times shy and hold themselves far aloof, nutcrackers usually impress one as being of a fearless nature. They are wont to visit camps, and will hop down familiarly among the articles of camp equipment to glean scraps of food. This propensity has lead to their being characterized by some mountaineers as camp-robbers. In our experience this familiarity has been of only pleasing consequence, for we have thus become better informed of the birds and their habits.

So far as known the Clark Nutcracker does not commonly stand in the same unfortunate relation to other birds which nest within its range as do the California and Blue-fronted Jays. Still, on July 13, 1915, at Tuolumne Meadows, a Western Robin was seen in excited pursuit of a Clark Crow. The robin gained on the object of its chase and was seen to strike several feathers from the nutcracker's back. Whether the nutcracker had been disturbing the robin's eggs or young was not known.