Cogswell 1950 2 Retrochelidon pyrrhonota July 24 Boca Res, 5360 ft., Nevada Co., Calif. - an estimated 150 seen over flats E of reservoir and in the gorge below the spillway. Stopped to look at the nests, which are placed in about 5 rows in the angles between the overhead & its supporting beams. Some nests had open fronts (= 1949 nests?), but many had the full gourd shape. Birds were going to several of these frequently, & adls. were seen peering out of some. No count made, but no. nests somewhere above. 30 July 26 along highway US-395, S of Reno, Washoe Co., Nev. - about 10 seen Little Washoe Lake, 5020 ft., Washoe Co., Nev. - about 20 est. in a very open flock foraging high above lake. This sp. was present here regu. early in 1948 also, probably nesting in nearby village of Washoe. July 27 - Brosser Cr., 5650 ft., 1½ mi. E, 3½ mi. N Truckee Nevada Co., Calif. - 50± flying about over grassy valley & nearby sagebrush slopes. They nest here on the old (now abandoned) "Brosser House" (stage station?). - Little Truckee R., 5800 ft. Sierra Co. 3 mi. E, 5 mi. N Hobart Mills, Calif. - about 20 seen near the iron bridge, under which they are nesting. This valley is much like the Boca & Brosser Cr. areas in general physiognomy, & is directly upstream from former. Aug. 1 L. Van Norden, 6800 ft., Placer + Nevada Cos, Calif. - about 20 present, in flight over meadow a lake or perched on wires by mouth of Castle Cr. one of these was a juvenile.