BULLETIN OF THE COOPER ORNITHOL?)GICAL CLUB. 8 9 Some Winter Birds of the lower Colorado Valley. BY W. W. PRICE, STANFORD UNIVERSITY, CAL. [Read before the Northern Division of the Cooper Urn. Club, July x, r899.1 ROM Nov. 25 to Dec. ?5, ?898, was spen? in the Lower Colorado Valley about Yuma, Arizona, on the Lower Colorado at the head of the Gulf of California. The following notes are given not with any idea of completeness, but merely as containing some of the more interesting facts then and there noted.. The three weeks were exceptionally cold and stormy. The nights were often frosty, ice forming on rain-pools, even at the tide-water on the Gulf. Many of the small rodents and all the snakes and lizards had gone into hibernation. Coming from the Colorado desert on the line of the railroad, into the valley of the Colorado, one passes over a gravelly mesa, thinly grown with Larrea, Fran- seria, Chenopodium and an occasional Fonquiera.and Olneya. On reaching the al- luvial bottoms, here several miles wide, a few mesquite trees, (Prosopis) ar.e met with and everywhere the gray-green arrow-weed (Tessaria borealis), forms a dense, almost impenetrable undergrowth from five to eight feet high. These thickets are the favorite haunts of Abert's Towbees and countless Intermediate Sparrows. Near the river and along the sloughs are occasional cottonwood trees. Here were seen many birds mentioned in the list that follows. One general feature of the usual Arizona l?/ndscape surprised me,--the apparent absence of cacti. Only one species was observed, an opuntia, on the sandy mesa about Yuma. None were noted inthe alluvial bottoms of the Colorado or at the head of the Gulf. A word as to the topography. On the Arizona and Sonora side of the river the gently-sloping mesa stretches south and east many miles without a break in its surface, bounded only on the extreme eastern horizon by barren, desert moun- tains. On the Californian side, between the river and the lofty Cordillera,.the isolated desert ranges are ?nore numerous. Of these the Pinto, Cocopah and My- ola are the largest and from a distance of a few miles seem absolutely destitute of vegetation. In this region much of the country is lower than the banks of the Colorado, and subject to overflow during the summer floods of June and July, when the snow melts at the sources of the river. A little south of the Arizona-- Sonora line and about ten miles west of the river are some very remarkable hot springs and mud volcanoes. At the head of the gulf are wide, level mud-flats made up of silt continually brought down by the river. On the Californian side these are of much greater extent,--desolate flats, forty or fifty miles long and from ten to twenty miles wide on which absolutely nothing grows. They lie dose about the foothills of the desert mountains and are everywhere saline. Over the southern part meander shallow sloughs of crystal water so intensely salt that great masses of pure rock salt cover the bottoms and are piled up in glistening banks along the margins. In 'places the surface of the flats is soft, slimy mud into which the foot sinks an inch or more; in other places the surface is hard, cracked by the sun and covered by a frost-like salt incrustation. This whole region is overflowed by the high spring and summer tides, the height of which is determined by the direction of the. wind and the volume of water in the river. A southern gale at the time of the summer floods causes the highest rise in the tides. All along the river bank and gulf shore, a.nd sometimes scattered far inland over the mud flats, are great "windrows" of drift brought down by the floods. In these may be noticed many kinds of woods:--1ogs of willow,.cottony wood, pine and juniper with occasional railway ties and bridge timbers. From Yuma southward to the Gulf of California there seem to be three dis- tinctive floral areas, but the bird life does not appear so c!early differentiated. First.' there is the flora of the sandy, gravelly mesa, more typically "desert" than that of either of the other floral areas. It is .characterized by a rather uniform growth of Larrea lridentata through which are interspersed occasional bushes of Asclepias subulata, Dalea emoryi, ?bnquiera splendens, Olneya , Franseria ... Chenopodium and ,4rtimesia The vegetation is nowhere dense; the
