How Do They Find the Old Home?
The return of the birds to their old homes and how they find their way back to the same spot every year, to do which they must sometimes travel thousands of miles, is one of the most marvelous things in nature and has not as yet been satisfactorily determined. The nearest approach we have to a satisfactory answer to this is that birds do have a memory, that they can and do recognize familiar objects, and that their love for the old home causes them to fly to the north until they recognize the landmarks of their former habitation. In this it is said that the older birds—those who have gone that way before—lead the flocks and show the way.
There is no doubt that birds have a more perfect instinct of direction than man. They can follow a line of longitude almost perfectly, i.e., they can pick out the shorter route by instinct, and this is, of course, a straight line. They just keep on going until they come to the familiar place they call home and then they stop and build their nests. That it is not memory and sight of places alone that guides the birds is shown by the fact that some birds when migrating fly all night when there is no light by which to recognize familiar objects.