BIRDS

Fabulous Feathers: Birds are distinguished from other animals by their feathers. Feathers help birds fly, of course, but they also serve many other functions. They provide insulation in cold weather and waterproofing for birds that swim (or are caught in rainstorms). They come in a seemingly infinite variety of colors, allowing birds to identify their own species, hide from predators, communicate with one another and more.
Bird Basics: All birds have modified forelimbs, or wings, which allow the majority of them to fly. Their high metabolic rate, strong, lightweight skeleton and unique digestive and respiratory systems are also adaptations for flight. In lieu of teeth, birds possess a beak, which they use for feeding, grooming, manipulating objects and more. They lay hard-shelled eggs, which protect their young, and are bipedal, meaning they walk on two legs.
Feathered Friends: These highly social animals communicate with one another not only through visual signals, but also through calls and complex songs. Birds participate in a variety of social activities such as cooperative breeding, where sometimes thousands of birds nest together in one location, and cooperative hunting, where they work together to capture their prey. They will join forces to mob predators, and many species flock and migrate together in massive numbers.
Bird-Brained?: Birds are highly intelligent. In fact, the most intelligent bird species are considered among the smartest animals on the planet. These "bird brainiacs" been observed manufacturing and using their own tools, activities attributed solely to higher mammals until recently. Some social bird species are known to pass cultural knowledge on to later generations, a phenomenon seldom seen in the animal kingdom.

http://animal.discovery.com/birds/