SIERRA GROUSE. Dendragapus obscurus sierrae Chapman

Field characters.—Fowl-like in appearance; size large (fully five times bulk of Mountain Quail); general effect of coloration dark bluish gray; tail almost square-ended, with a light band across tip (often appearing almost white by contrast). Close view shows the plumage to have a complex pattern of lighter markings. Flight direct, heavy, with loudly whirring wings; when descending, often sails with wings set. Voice: Of male in breeding season a deep, wooden, far-carrying ventriloquial unt, wunt, wunt', wunt', tu-wunt', wunt, wunt; of female with young, clucking notes; of both sexes, an alarm note, kuk, kuk.

Occurrence.—Fairly common resident, chiefly in Canadian Zone and locally in upper Transition; ranges upward into Hudsonian Zone during late summer. Westernmost station of occurrence, Merced Grove; easternmost, Williams Butte. Noted frequently around rim of Yosemite Valley, as at Glacier Point, Artist Point, and in vicinity of Yosemite Point. Lives in or near the heavier coniferous trees.

Acquaintance with the Sierra Grouse may begin in several ways, but rarely does it come in the conventional manner through which we learn to know most birds. Upon entering the Jeffrey pine and red fir forests of the Canadian Zone in spring and early summer, one may often hear a very un-bird-like, dull sodden series of booming notes that have a ventriloquial quality. These are the courting notes of the male grouse. Less often, whatever the time of year, the introduction may come suddenly and much more impressively when, close at hand, a heavy-bodied 'blue grouse' rises quickly from the ground and makes off through the forest on loudly whirring wings, and showing an expanse of square-ended gray-banded tail. When a small flock of the birds get up, as they often do, in rapid succession, or even simultaneously, the aggregate effect is bewildering, to say the least.

The Sierra Grouse lives in the high country throughout the year, never migrating to lower levels as does the Mountain Quail. The thick heavy plumage and legs feathered clear down to the toes enable the grouse to withstand the cold of the midwinter months; while their ability to subsist on pine and fir needles assures them at any season an abundance of food to be easily obtained without seeking the ground.

During the spring and early summer, the males are in the habit of taking solitary positions near the tops of pines or firs, sixty or more feet above the ground, where they stand on horizontal limbs close to the trunk. They hold such positions continuously for hours, one day after another, and send forth at intervals their reverberant booming. With different birds the series of notes comprising this booming consists of from five to seven syllables, six on an average. The quality of the sound can be likened to that produced by beating on a water-logged tub, boont, boont, boont', boont', boont, boont, crescendo at the first, diminuendo toward the end of the series. As each note is uttered the tail of the bird is depressed an inch or two—perhaps an index to the effort involved. The separate series of notes in two instances were uttered at intervals of 40, 20, 25, 45, 12, 21, and 29 seconds, and again 10, 10, 20, 26, 14, 15, 17, 12, 11, 15, 13, 28, 17, and 11 seconds respectively. These two birds had been heard booming for a long time before we began to pay special attention to them; and they continued long after we finished this record. The ventriloquial quality is discovered when one attempts to locate the producer, a difficult feat as a rule. The observer may succeed in locating the proper tree, but is likely to circle it many times, peering upward with painfully aching neck, and still utterly failing to locate the avian performer amid the foliage high overhead. The notes are commonly supposed to be produced by the bird's inflating and exhausting the glandular air sacs on the sides of the neck. These sacs are covered by unfeathered yellow, skin, and we think it more likely that they serve only as resonators, being kept continually inflated, while the air actually producing the sound passes to and from the lungs along the regular air passage. It rests with someone gifted with patience for long continued observation to determine exactly how the notes are produced.

By early July the new broods of grouse are to be looked for in the brush-bordered glades of the forests. Two downy young were noted on the trail to Nevada Falls so early as June 21, 1893 (W. O. Emerson, 1893, p. 179). When the chicks have been partly reared the males desert their mates, and, forming in flocks of 6 or 8, work higher in the mountains. The females remain with, and continue to care for, their offspring, these family units remaining separate for the time being. Finally, as the summer wanes, they, too, work up into the Hudsonian Zone. Thus, while the Mountail Quail go down-hill in the fall, the grouse go up-hill.

A 'stag' flock of 8 Sierra Grouse was encountered by the senior author on Warren Fork of Leevining Creek, September 26, 1915, after a light fall of snow. The birds were in lodgepole pines on a level bench at 10,500 feet altitude. They flushed one after another with a startling succession of loud whirs, all taking off in the same general direction and alighting about four hundred yards away. When followed up 5 were flushed again, 3 from the ground and 2 from the trees.

One of the above mentioned male birds was shot and its crop was found to contain 1520 needle tips of the lodgepole pine. The bitten-off ends of needles varied from one-fourth to one inch in length. The crop also contained a few fragments of very young pistillate cones. The bill of this bird was smeared with pitch. The crop of an adult female grouse obtained at Walker Lake held eleven ripe rose hips, and the gizzard was filled with the hard seeds of the rose, together with grains of quartz which of course had served to grind the resistant portions of the bird's food.

We have only one incident to record concerning the enemies of the Sierra Grouse. While camped at Walker Lake on September 10, 1915, our packer noted a large hawk eating something in a pine tree. At his approach the hawk flew away, leaving its meal unfinished, and the packer found the remains of a Sierra Grouse. The victim was an old female in worn plumage and had just begun to molt. The hawk had eaten the flesh on one half of the grouse's breast. The identity of this particular hawk must remain unknown; but we have reason to believe the Western Goshawk to be an important enemy of the Sierra Grouse. Tree-climbing carnivores such as the Sierra Pine Marten and Pacific Fisher probably destroy some grouse each year.