Page:Bird-lore Vol 08.djvu/75

 Legs and Feet of Birds By C. WILLIAM BEEBE Curator of Birds, New York Zoological Park c ,ARRIED far and wide by the power of flight, no two species of birds have exactly similar en- vironments. Thus we realize the need for many varied adaptations in the way of feet and legs. When the wings cease their labor and are folded close to the side, the bird must depend upon its feet to carry it to its food and to keep it out of danger, — whether its footing be in a tree-top or on a cliff; in shallow water or on the deep; in mud, sand or snow. Although birds are descended from five-toed ancestors, yet no living bird, and none of those which we know only as fossils, has more than four toes on each foot. The disposition of these toes, — four, three or two, as the case may be, — is always in accordance with the habits of the bird. The most common type of avian foot is that in which the arrangement is of three toes in front, with the fourth, corresponding to our great toe, pointing backward. This was the arrangement in the fossil Archaeopteryx, and for perching birds, as well as for many others with very different habits, it has stood the test of the six millions of years, or thereabouts, since the days of its venerable prototype. A classification of birds, generally accepted for many years, was based on the uses of the feet, or mode of locomotion. In this scheme birds were divided into the Runners, Scratchers, Climbers, Swimmers, Perchers, etc. Although these exact divisions have long since been abandoned, yet it is worthy of note that even in the most modern classifications many of these groups hold good, although based on other and more fundamental characteristics. Examples of these are the Ostrich -like birds, or Runners; the Fowl-like birds, or Scratchers, and the Passeres, or Perching birds. From the tiny limbs of a Hummingbird to the gigantic shanks of an Ostrich, the legs of birds, with very few exceptions, are covered with scales, — most emphatic reminders of the reptilian ancestry of both these extreme (50 RED-CRESTED COCKATOO Showing two uses of the feet