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?4 z THE CONDOR I Von. V When a considerable number of cormorants had congregated they seemed to become suddenly animated by a common purpose and followed one another in swift flight to the foot of the rapids. There most of the assembled birds alighted and formed a line across a considerable section of the river. Then with flapping wings, beating the surface of the water into foam, the black line moved up stream, the birds showing much excitement but keeping their places very well. The sur- face of the water was churned to spray by the strokes of so many powerful wings and feet, yet in the midst of the apparent confusion the birds could be seen darting to one side or the other, or spurting a few feet ahead of the line, and sometimes disappearing for a moment below the surface but nearly always securing a fish. When they reached the head of the rapids the birds flew heavily to their perching stones or swam slowly up the quiet surface of the river. After a short rest the YOUNG MEXICAN CORMORANT, LAKE OHAPALA, JAN. 51 $903 line would reform and again beat up the rapidils and this was repeated until the birds had satisfied their hunger. The cormorants evidently fully appreciated the advantages of thus working in company, so that a fish trying to escape from one bird would almost certainly be- come the prey of another. The purpose of beating the surface of the water with their wings was evidently in order to alarm and confuse the fish so that they would dart blindly about and become more easily captured. I have seen parties of gannets doing the same thing in the midst of schools of fishes off the Tres Marias Islands. When the cormorants were gorged they deserted the fishing ground for the day and streamed back down the river to the lagoons where they perched motion- less for hours in la. rge mangroves or other trees along the edge of the water.