Remsen, J.V. 1975 Bonaparte's Gull Larus philadelphia May 6 Sloans Lake, Jefferson Co., Colo.: 5 May 10 Jumbo Res, Logan Co., Colo: 4 Nov.27 Oceanside; San Diego Co. Calif.: 150, 25 on Buena Vista Lagoon apparently were using Double-crested Cormorants to heard fish. A flock of about 13 cormorants were fishing together in a line, swimming across the lagoon with the line somewhat diagonal to direction of movement. The gulls were hovering above the cormorants, diving down in front of the line of cormorants to pick objects, presumably fish, from the surface of the water. In the flock of gulls were 9 2nd-yr. Western Gull and a 1st-yr. Ring-billed Gull, doing the same thing. The cormorants were constantly diving and often no more than 3 were up at any one time. They moved from the center of the lagoon to the northern shore and then all the way back across the lagoon to near the southern shore, all the time accompanied by the same group of gulls, constantly hovering just above and in front of the cormorants. All of this took about 15 minutes.