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Nov., 1922 DISTRIBUTION OF JIIOLO7HRUS .4TER IN CALIFORNIA 207 following localities: Imperial County: Calexico, Bard, Lan0, Potholes, Pilot Knob; Riverside County: Mecca, Neighbors, Riverside; San Bernardino County: Lavic, Yermo, Victorville, Colton; Inyo County: Death Valley, Panamint Moun- tains, Independence, Shoshone; San Diego County: San Diego, National City, Borego Springs, Vallecito; Orange County: Anaheim Landing; Los Angeles County: Baker, Los Angeles, E1 Monte, Pasadena; Ventura Cottory: Oxnard; Santa Barbara County: Goleta. REdA}ms: Broadly speaking, the life zone occupied by obscurus is Sonoran, with centers of abundance in the Lower Sonoran Zone along the Colorado l?iver, at desert oases, such as Mecca, and in the irrigated sections of the Imperial Val- ley. The race is probably resident over its entire California range; certainly so in the southern part of the State. Specimens from the northern part of the San Diegan District are intermediate toward californicus. Molothrus ater artemisiae Grinnell Nevada Cowbird Range in California: In summer, the east-central section of the State, from Death Valley, the Panan3int Mountains, and Independence, north to Mono Lake; also the northeastern section, in the Modoc region. In migration, and in winter, widely distributed over most of the State. Record stations outside the normal breeding range are: Los Coronados Islands (Lower California), September 5; Farallon Islands, June 2; Borego Springs, April 30; Neighbors, October 14; Yermo, June 7; and Mount Bullion, December 27. The record from the Sacra- mento Valley cited by Baird(?) may pertain to this form or to californicus. Of the 49 specimens examined, 26 are from the following California localities: Los Coronados Islands (Lower California); San Diego County: Borego Springs; Riverside County: Neighbors; San Bernardino County: Yermo; Inyo County: Furnace Creek Ranch, Death Valley, Panamint Mountains, Independence, Laws; Mono County: White Mountains, Mono Lake, Oasis; Modoc County: Alturas; Mariposa County: Mount Bullion. RE?A}?KS: As a breeding bird, the Nevada Cowbird is much more widely distributed zonally than either of the other forms occurring in California, since it ranges from Transition (Alturas), through Upper Sonoran (Mono Lake and Owens Valley), to extreme Lower Sonoran in Death Valley. Moreover, this race is distinctly migratory, whereas obscurus and cali[ornicus appear to be nearly or entirely resident. The sporadic occurrences du?'ing the summer at Yermo and on the Farallones can be most logically accounted for by considering these individuals as late or strayed migrants. A certain amount of intergradation takes place between artemisiae and o?scu?'us in Death Valley, the Panamint Mountains, and Owens Valley, par- ticularly in the southern part. In addition, certain rather small examples of artemisiae from Mono Lake are undoubtedly accounted for by an infusion of obscurus blood. /?owever, the blending of the two races is by no means the gradual one which is generally found in the intermediate area between two sub- species. This very imperfect fusion of the two forms probably indicates either a recent invasion of the range of one form by the other, or else a recent simul- taneous occupation by both forms of an area formerly uninhabited by the spe- (D l?eports of Explorations and Surveys from the l?ississippi l?iver to the Pacific Ocean, 1853-56, Vol. 9, pt. 2, pp. 524-52?.