Flying to and fro over the sea, or over a large inland lake, you may sometimes see a number of birds which look like gulls, but are much smaller, and have long, forked tails like swallows. These are terns, or sea-swallows, as they are often called, and are most elegant and graceful in their movements, gliding and sweeping through the air, and twisting and turning with the most wonderful swiftness and ease. They are summer visitors only, coming to us in May and flying south again in September, and they breed on flat shores, generally laying their two or three eggs in a small hollow in the shingle. They feed on small fishes and shrimps, and also on the sandhoppers and the various insects which are so plentiful upon the beach. [Illustration: AMERICAN WADING BIRDS. 1. Great White Egret. 2. Sandhill Crane. 3. Great Blue Heron. 4. Whooping Crane. 5. White Pelican (Male). 6. Snow Goose.] GUILLEMOTS Very common are guillemots on some coasts where there are sea-fronting cliffs, and freedom from disturbance. Thus they abound along the shores of Labrador and Greenland, and many varieties are to be found along the northern coasts of Alaska, and about the borders of the Arctic sea, often thronging in great numbers together with puffins, kittiwakes, petrels, and gannets, each kind occupying separate parts of the cliffs and living on friendly terms with their neighbors. Guillemots feed entirely upon fishes, which they chase under water, using both their wings and feet, just as dabchicks do. They do not make any nest, but lay a single egg on a bare ledge of rock which is often only a very few inches wide. One would think that this egg would be in great danger of being knocked over the edge. But it is very large at one end and very much pointed at the other, so that if it is struck it only rolls round and round. In color it is green or blue, blotched and streaked with black. THE ALBATROSS One of the largest of all the sea-birds is the albatross, which is found chiefly in the tropical seas. When the wings are fully spread, they sometimes measure nearly twelve feet from tip to tip. Yet the entire weight of the bird is not more than sixteen or seventeen pounds. It often remains at sea for weeks or months together, sometimes remaining in the air all through the night as well as all through the day, and following ships for hundreds of miles in order to feed upon the refuse which is thrown overboard. Its appetite is enormous, for it has been known to gulp down a great piece of whale's blubber, weighing between three and four pounds, and then to return almost immediately for more! Great numbers of albatrosses nest together on uninhabited islands, each pair scooping together a quantity of clay, grass, and sedge, which they arrange in a conical heap about ten or twelve inches high, with a little hollow at the top. Only a single egg is laid, which is quite white, and is rather larger than that of a goose.