A million years, perhaps, passed by, and then another million, and maybe another million still; and the birds without wings and with teeth were no more. In their places were other birds, much smaller--birds with wings and no teeth; but something like them, for all that: for their feet also were fitted for swimming and not walking, and they, too, visited the shore little, if at all, except at nesting-time, and they lived upon fish in the water. And what their voices were like, all men may know who will go to the wilderness lakes and listen; for, wonderful as it may seem, these second birds have come down to us through perhaps a million years, and live to-day, giving a strange clear cry before a storm, and at other times calling weirdly in lone places, so that men who are within hearing always say, "The loons are laughing." Gavia was a loon who had spent the winter of 1919-1920 on the Atlantic Ocean. There had hardly been, perhaps, in a million years a handsomer loon afloat on any sea. Even in her winter coat she was beautiful; and when she put on her spring suit, she was lovelier still. She and her mate had enjoyed the sea-fishing and had joined a company of forty for swimming parties and other loon festivities; for life on the ocean waves has many interests, and there is never a lack of entertainment. The salt-water bathing, diving, and such other activities as the sea affords, were pleasant for them all. Then, too, the winter months made a chance for rest, a change from home-duties, and a freedom from looking out for the children, that gave the loons a care-free manner as they rode the waves far out at sea. [Illustration: Immer Lake.] Considering all this, it seems strange, does it not, that when the spring of 1920 had gone no further than to melt the ice in the northern lakes, Gavia and her mate left the sea and took strong flight inland. What made them go, I cannot explain. I do not understand it well enough. I do not really know what urges the salmon to leave the Atlantic Ocean in the spring and travel up the Penobscot or the St. John River. I never felt quite sure why Peter Piper left Brazil for the shore where the blue-bells nod. All I can tell you about it is that a feeling came over the loons that is called a migration instinct; and, almost before Gavia and her mate knew what was happening to them, they had flown far and far from the Ocean, and were laughing weirdly over the cold waters of Immer Lake.