There are an estimated 9000 species of birds, also called Aves, worldwide. They are known mostly for flight, although not all birds can fly.
Some birds are also recognized for their singing or their bright coloring.
Birds come in many sizes and colors. They have different habits and behaviors. Still, there are some characteristics that all birds have in common.
Birds are characterized by feathers, toothless beaked jaws, a high metabolism, a four-chambered heart, the laying of hard-shelled eggs, and a strong, lightweight skeleton.
They are adapted to fly, but some birds, like penguins, have lost their flying ability. Despite losing the ability to fly, these birds still have characteristic wings and feathers.
Where do birds live?
Birds can be found all over the world in all types of habitats. Some birds prefer land, while others like to live in or near water.
Some birds build their nests on the ground, while others nest in the highest treetops. Birds even build nests from different materials: mud, sticks, moss, and sometimes even human hair or animal fur.
Many birds migrate, taking seasonal flights to areas where more food and resources can be found.
What do birds eat?
Birds eat a variety of foods. These may include berries, nuts, fish, insects, and carrion (dead animals). They also eat seeds, grains, and grasses.
Raptors like owls, eagles, and hawks can eat small mammals. Some species have specialized diets. Hummingbirds, for example, have beaks that are designed to eat nectar.
The habitats, behaviors, diets, and appearance of birds can vary, but they do share some common features.
Birds can be identified by their feathers, eggs, beaks, and strong, lightweight skeletons adapted for flight. They also have four-chambered hearts and especially high metabolisms.
Browse our Bird Facts: