Cogswell 1948 Colymbus nigricollis 1 Nov.5 - N.of E.end of Oakland Bay Bridge, Alameda Co. Calif. 14:00-15:00 - Several on open bay among and for near the large flocks of ducks flew at approach of the boat. Others dove to escape us. Dec.18 Tomales Bay, Marin Co. Calif. - See C. auritus for notes on relative nos. & differentiating characters. Jan.29 - Dumbarton Bridge, Alameda Co. Calif.- Several groups of 5 to 20 each were feeding in pheldrope fashion by swimming about rapidly & picking something up from surface of water by quick dabs of the head & neck. One group of 20+ was working in a close formation, others were more scattered. All this was on the diiked salt ponds of the Leslie Salt Co. near the K60 Transmitter. A few of the birds were also seen diving.