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32 ? THE CONDOR Vol. XIV thickets in the valleys and along the mountain streams and singing exactly like eastern birds of this species. The other is the breeding bird of the region. It inhabits the fir forests in the mountains and has a totally different song, as described in the Auk, xxvIII, 1911, p. 48. I secured adult males of both forms but could find no difference in plumage or measurements. l?yadestes townsendi. Townsend Solitaire. A common summer resident in the mountains throughout most of the region, particularly in the very rocky country in parts of Jefferson and Silver Bow counties. Migration dates March 15, 1910, October 2, 1909, and October 14, 1910. Hylocichla fuscescens salicicoh. Willow Thrush. Common summer resident in willow thickets of the valleys and lower mountain streams. Migration dates June 5, 1910, June 5, 1911, and August 27, 1910. Hylocichla ustulata swainsoni. Olive-backed Thrush. Common summer resi- dent of the mountains. Migration dates May 16, 1910, May 14, 1911, and August' 25, 1910. A large flight of thrushes of this and the next species was noted in late August on Gold Creek. On one unusually cold day during the flight I found an Olive-back, so numb with cold that I caught it in my h?nds. Hylocichla guttata auduboni. Audubon Hermit Thrush. Common summer resident of the mountains. Noticeably much commoner than farther east in Mon- tana. Migration dates are May 25, 1910, May 17, 1911, September 28, 1909, and September 10, 1910. Plane?ticus migratoritm propinqutm. Western Robin. Common summer resi- dent in both valleys and mountains. Also a rare winter resident. Migration dates are March 16, 1910, October 23, 1909, and October 13, 1910. Sialia currucoides. Mountain Bluebird. Common summer resident. Migra- tion dates, March 10, 1910, and October 7, 1909. BIRDS OF A MOHAVE DESERT OASIS By CHESTER LAMB HE locality of which I am about to write, is known as the Dagget? region, formerly famous on account of its Borax mines. It is situated in the Mohave River Valley about forty miles northward from the south-central edge of the Mohave Desert, and one hundred and sixty miles northeast of Los Angeles. The valley here is about ten miles wide; on the north are the Calico Mountains, and on the south the Ord Mountains. These are low ranges entirely bare of vegetation except the ever present creosote bush. The floor of the valley is about two thousand feet above sea level. In about the center of the valley flows the Mohave River, that is, it flows about three months of the year, from February to May, and the rest of the year it is a burning streak of sand except in a few places where the water comes to the surface and where cottonwoods, willows and mesquites grow, forming veritable oases. It is at one of these oases that, with a few exceptions, all my observations w?ere made. In fact, of the one hundred and thirty-three species and subspecies noted, only forty-three were seen at all at other points. The oasis in which my observations were made is nine miles east of the town of