Cogswell 1948 Aythya affinis 1 Nov. 5 - N. & E. end of Oakland Bay Bridge, Alameda Co., Calif. 14:00-15:00 - A conservative estimate of at least 10,000 scamp in 2 large, well spread out flocks in area between the bridge, Berkeley Isld., and Treasure Id., — which area we covered fairly well from the boat operated by bridge employees. They were pretty wild, flying en masse as the boat approached within easy field binocular range. None were seen diving although they may have before we bothered them. The vast majority of all waterfowl present were of this species. Females outnumbered full-plumaged males. Dec. 5 - Jewell L. Tilden Park, Contra Costa Co., NE of Berkeley, Calif. one ? in mid-pond flew away with Canvasbacks & Ring- necks, while another ? which had been in close to E shore, merely scam out to the middle of the pond when we came into the open on road E of pond. This latter bird was accompanying a ? A. collaris. They flew away together after we approached it more closely.