In this way pelicans carry back food for their hungry little ones. But on their way they are sometimes robbed, for there is a kind of large hawk which is very fond of eating fishes, but is not at all fond of the trouble of catching them. So he waits till he sees a pelican returning home from a fishing expedition, and then dashes at it, and begins to beat it about the head with his wings. The poor frightened pelican, thinking that it is about to be killed, opens its beak to scream. This, of course, is just what the hawk wants, and snatching a fish out of the pelican's pouch, he flies off with it in triumph. Pelicans are very plentiful in many parts of the world, and are often seen in vast flocks. We have two kinds in the United States and Canada--the white and the brown. Both are more numerous on the marshes and around the shallow lakes of the northwestern plains than anywhere else, because they have been driven from their former coast-resorts. All the birds in a flock will sometimes go out fishing together. Arranging themselves in a great semicircle, about a yard apart, they all paddle slowly forward, and in this way will drive a great shoal of fish into shallow water, where they may be snapped up without difficulty. SEA-GULLS These you know very well by sight, for they are common on all parts of our coasts, and on many of our lakes, while numbers of them may be seen even on the ornamental waters in the parks of New York and other seaboard cities. In stormy weather, too, they often fly inland, and sometimes great numbers of them may be seen in newly plowed fields, hunting for worms and insects. Most of them go north for the breeding-season, some visiting certain islands and rocky cliffs in immense numbers, and making their nests of seaweed; while others, like the black-headed gull, and the ringbill nest in marshes, merely trampling down the broken tops of sedges and reeds, and so forming a slight hollow in which to lay the eggs. At least fifty different kinds of gulls are known. But many of them are very difficult to distinguish, for their summer plumage may be quite unlike that with which they are clothed during the winter, while the young birds are not marked like their parents till they are two or even three years old. Those which are most common on the Atlantic coast are two or three kinds of herring-gulls, which formerly bred in great numbers on all our sandy shores and islets, but now have been driven to quieter regions in the far north. On the western plains, around certain shallow lakes, live great colonies of ring-billed and other small gulls, breeding in the extensive marshes.