Birds may seem like mysterious creatures, but even if their size and appearance bear no resemblance to ours, we share some of the same physiological traits. This is especially true of their eyes, which function similarly to a camera's zoom lens -- just like ours. Even if their ears are hidden away, behind and just below their eyes, they function like ours and can pick up a wide range of frequencies. Like us, birds breathe through their nostrils, and we share a sense of smell that's adequate but not equal to animals who rely on it to escape dangerous situations.
Even their feather-covered wings share some of the same physical principles. Their wing tips feature primary flight feathers -- essential to birds -- which serve as their version of hands. Their secondary flight feathers correspond to the human forearm, while their covert feathers are analogous to the upper arm. There is, of course, a limit to the similarities: Each year, all birds lose their feathers and regrow them through a process called molting. Remember, if you own a bird, you'll need to monitor its diet closely during the molting period, which saps a good deal of the bird's natural nutrient reserves.