Cogswell 1948 Aythya collaris 1 Nov. 27 - Jewell L., Tilden Regional Park, Contra Costa Co. NE of Berkeley, Calif.. 2 males (1 in some- what intermediate plumage) and 2 females. Flew away with rest of ducks when we approached shore of lake. Dec. 5 2 ♂ and 1♀ on Jewell L. This A.M. The males, I think, were likely the same 2 as above, since one was still obviously not yet in full drake plumage. They both flew away with the canoe backs upon our first approach into the open near the south east shore, but the single female swam out into the middle of the pond & remained until we came considerably closer. She was keeping company with a 4 Scamp rather than with the ♂ Ring-necks.