What is "bird"?

Bird refers to a diverse group of warm-blooded vertebrates characterized by feathers, beaks, wings, and the ability to lay eggs. They are found in almost every ecosystem on Earth, from the Arctic tundra to tropical rainforests. There are over 10,000 known species of birds, ranging in size from tiny hummingbirds to large ostriches. They are adapted to a wide range of feeding habits, including carnivorous, herbivorous, and omnivorous diets. Birds are also known for their unique songs, which they use for communication and mate attraction. They play important ecological roles, such as pollination, seed dispersal, and pest control. Many species of birds are also kept as pets or hunted for food or sport.