Our Bird Comrades

by Leander S. Keyser

"Among birds the paradoxical law that the smaller the creature the bigger the relative supporting wings holds good. A screech owl (Scops zorca) weighing one-third of a pound had 2.35 square feet of wing surface per pound of weight. A fish hawk (Pandion haliaetus) weighing nearly three pounds had a wing area of 1.08 square feet to each pound. A turkey buzzard weighing 5.6 pounds had a little less than one square foot of wing surface to each pound. A griffon vulture (Gyps fulvus) weighing 16.52 pounds had a wing surface of only .68 square feet to the pound.

"Students of aërial navigation who are devoting much attention to observations of birds say that if the peculiar law governing extant flying creatures could be fathomed the problem of human flight might be solved."

A BIRD'S FOOT

You will agree with me, after you have studied a bird's foot, that it is one of Nature's most wonderful contrivances, so admirably adapted for the purposes to which it is devoted that one cannot help feeling that a Divine Mind must have planned it, just as a man would make a watch for the express purpose of keeping time.

But what is properly included in a bird's foot? Here we shall have to correct a popular mistake, if we wish to be accurate, in the scientific sense of the term. Most people think that the avian foot consists only of the toes and claws, or the part that comes in direct contact with the ground or the perch. That, however, is an error, for the foot really comprises, in addition to the toes and claws, the first long bone of the limb, reaching from the base of the digits to the first joint. You will see, therefore, that the bird walks on its toes, not on its foot as a whole.

The long bone referred to—called the tarsus—corresponds to the instep of the human foot, that is, the foot proper, while the joint which extends backward, forming an angle with the next large bone, is really the bird's heel. Thus you perceive that most birds walk with their heels high in the air. What most people call the bird's "leg" is in reality the bird's foot, and what they call its "foot" comprises only its toes and claws.

To obtain a correct idea of the bird's entire walking apparatus, we begin with the uppermost part of the leg. As we proceed, it would be well to keep in mind the different parts of the human leg and foot. The highest bone is called the thigh bone or femur, which is, for the most part, enclosed in the general integument of the body, and is not entirely separate from it as is the thigh bone of the human leg. Among carvers it is known as the "second joint." It reaches forward and slightly downward, and is hidden under the feathers of the body. The upper end of the femur enlarges into a globular head, which fits into the socket of the hip in the pelvis, while the lower end meets another long bone, which extends obliquely backward and downward and with which it forms the knee joint.

The knee of the bird extends forward, as the human knee does when it is bent. By means of various nodules and tendons the femur is articulated with and fastened to the next large bone at the knee joint. This second bone is the leg proper, called in scientific language the crus. When, with its thick, palatable flesh, it is cooked and placed on the table, it is known as the "drumstick"—a favorite part of the fowl with hungry boys, vying, in their minds, with the "white meat" of the breast.

This important segment of the limb is composed of two bones, the larger of which is called the tibia, the smaller the fibula. At its lower end the tibia forms what is known as the ankle joint by articulating with the next long bone, which is commonly called the tarsus, although the proper name would be really metatarsus. It is not often that this bone is covered with flesh, and therefore it seldom finds its way to the table. Properly speaking, it is the larger part of the bird's foot, reaching obliquely upward and backward from the roots of the toes to the heel. If you will lift yourself upon your toes, holding your heels in the air, you will be able to form a correct idea of what the bird is doing whenever it stands or walks or perches.