SPURRED TOWHEES. Pipilo maculatus Swanson³²

Field characters.—Size large for a sparrow, bulk between that of Junco and Robin; tail about as long as body, and usually carried up at an angle with back. Whole upper surface and forepart of body, black; small spots ('tear drops') in rows on wings, larger spots ('thumb marks') at end of tail, and belly, white; sides of body orange brown. (See pl. 48c). Male with black more intense than in female; young quite different, streaked. Voice: A cat-like mewing call or alarm note, and a trilled song sounding like to-whee-e-e-e, the first syllable inaudible beyond a short radius.

Occurrence.—Fairly common at lower altitudes both east and west of Sierra Nevada. On west slope common in Upper Sonoran Zone but ranges up into Transition and downward locally into Lower Sonoran (subspecies falcinellus). Also east of the mountains in vicinity of Mono Lake (subspecies curtatus). In late summer and until severe winter weather, individuals wander upward through the Canadian Zone.³² Lives in brush thickets and forages on ground beneath such cover, seldom venturing into the open. Solitary.

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³²Two subspecies of the Spurred Towhee inhabit the Yosemite region, occupying separate territory, on the western and eastern flanks of the Sierra Nevada respectively.

SACRAMENTO SPURRED TOWHEE, Pipilo maculatus falcinellus Swarth. This is the race of the western slope of the Sierras, ranging in the breeding season from the vicinity of Snelling up as high as the floor of Yosemite Valley. In autumn, wanders still higher, as to Aspen Valley at 7000 feet and on Illilouette Creek at 6200 feet.

NEVADA SPURRED TOWHEE, Pipilo maculatus curtatus Grinnell, the race of the Great Basin area, enters the Yosemite region from the east and breeds in the vicinity of Mono Lake, where found by us at Mono Lake Post Office, near the mouth of Leevining Creek, and about the base of Williams Butte. One individual was obtained in Glen Aulin, 7700 feet altitude, October 4, 1915, which would seem to indicate a westward movement of this interior race in autumn over the Sierran crest.

The differences between the two races, falcinellus and curtatus, are so slight that only specimens in hand can be distinguished. Curtatus, as compared with falcinellus, shows a shorter hind claw, a smaller bill, a shorter tail, a greater amount of white on shoulders, wing coverts, and tail, and paler tone of coloration on sides and lower tail coverts.

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In the group of big ground-dwelling sparrows which includes the towhees and fox sparrows, the Spurred Towhee exhibits an extreme type in both structure and coloration. Its stout body, long tail, short rounded wings, large legs and feet, and heavy curved claws (pl. 48c) proclaim it to be a brush dweller and ground forager. The short wings and long tail may serve to enable it to move about rapidly within obstructing growths where locomotion must be accompanied by many short turns and twists, while the heavy armament of claws makes scratching a productive method of unearthing food.

The preferred haunt of the Spurred Towhee is a ravine-side thicket within ready reach of water. The birds venture into the open somewhat more than do fox sparrows but not so much as do the brown towhees. During the warmer months the leaf-covered brush and tall growths of grass and other annual plants form protecting shelters under which the Spurred Towhees can forage unseen; but in midwinter and early spring when rain and wind have battered down the grasses and shaken off most of the leaves the birds are much more exposed. Even then their broken pattern of coloration would be protective in effect were it not for their almost incessant activity. But when a towhee takes flight from one thicket to another its brilliant coloration flashes forth vividly; a predominance of black is seen, but the white dots on the shoulders and wings, and the white 'thumb marks' at the end of the fan-shaped spread tail, introduce a decided element of contrast.

The spotted towhees closely resemble the fox sparrows in manner of foraging. They habitually scratch in the earth and leaf mold under thickets and berry tangles, repeatedly springing up and kicking backwards with both feet at the same time. Often an observer's attention is first attracted to the presence of the birds by the sight or sound of the small showers of debris resulting from this vigorous mode of foraging.

During the breeding season the males are accustomed, particularly toward evening, to ascend by series of short hops and flights to the tops of large bushes or small trees, and there to repeat their monotonous but not unpleasant song, tu-wheeze. At other seasons of the year they are content to remain within the shelter of the brush. In the breeding season the birds are very excitable and readily respond to squeaking noises. This trait is undoubtedly correlated with a feeling of concern for mates or young; for in midwinter when the reproductive instincts are at a low ebb the Spurred Towhees are not easily to be 'squeaked' out into full view.

The nest of the Spurred Towhee is a deep cup-shaped affair placed on or sunk in the surface of the ground. One found by Mrs. Joseph Grinnell in Yosemite Valley was a deep cup of pine needles, bark, and grass stems, lined with fine round grass stems and a little black horsehair. It was situated among strawberry plants and under a small chokecherry bush. The four eggs were finely marked with reddish brown on a creamy ground color. Two days after discovery this nest was raided, seemingly by some animal which had burrowed up into it from the ground beneath. Whenever the nest was visited, even after the contents had disappeared, the parents were always in attendance and scolded violently. A second nest, of similar construction, was located under a canopy of dried ferns at the base of a small stump. When first found, on June 12, 1915, it contained 4 eggs. On the morning of June 24 it held one young bird, and two more hatched out that same afternoon. The fourth chick died while attempting to crack open its shell. Up to the time the eggs were hatched the owners of this second nest, upon being disturbed, slipped away quietly, but after their brood had emerged they changed their behavior, and were then accustomed to stay about and insistently voice their solicitude. The young in juvenile plumage have streaked breasts, but by fall they have assumed the plumage of their parents.

In the fall after the breeding season and before the arrival of winter snows, the Spurred Towhees wander higher in the mountains, ranging throughout the greater portion of the Canadian Zone. In late September and in October they have been seen on Illilouette Creek above the falls, on the Snow Creek trail at 6000 feet, and at 7000 feet, near Aspen Valley. This spilling upward is thought to be due to overpopulation of the lower zones as a consequence of the appearance of the fully grown young of the year. It has been further suggested that the young of the year, among animals generally, exhibit instinctively a sort of wanderlust, of benefit to the species in that new territory is thereby sought out and sustenance made available for an increased number of individuals. Of course, when winter comes on, burying the food at the higher levels, this wave of vagrant individuals is pressed back again; but beneficial readjustments doubtless occur in the population even within the regularly occupied area.