Some would call it quirks of evolution, but when you believe that God created all things, you have to think that perhaps God smiled as He made some of the little creatures and birds of the air whose designs are so specialized that they do certain things that no other creature can do, yet can't do what other birds or animals do quite easily. Like what? Consider the following:
A buzzard can be placed in a pen two to three meters square, entirely open at the top, and in spite of his ability to spread his powerful wings and soar--perhaps not with eagles but certainly above the treetops--he can't get off the ground. Why? A buzzard has to have a running start, he needs three to five meters of runway to get airborne, and without it, the buzzard is imprisoned by only a fence.