Birds are a diverse group of animals, with over 10,000 species worldwide. Some common examples include the sparrow, known for its small size and chirpy songs, and the eagle, recognized for its powerful build and keen eyesight. Many birds, like the hummingbird, are known for their ability to hover in place while feeding on nectar. Other notable species include the penguin, which is adapted to life in cold climates and is unable to fly, and the ostrich, the largest bird that can run at high speeds. Birds play essential roles in ecosystems, such as pollination and seed dispersal.