Bird fossils are rare because bird bones are hollow and fragile. Most birds can fly , some swim , and some do both. Many species of birds migrate seasonally . Many Songbirds are becoming rare. There are about 9,000 different species of birds, divided into about 25 orders .
Ornithology is the study of birds.
BIRD FOOD Birds spend most of their time looking for food. They use their beaks to catch bugs , worms , small mammals , fish , fruit , or nectar . Birds play an important part in the control of insects, the dispersal of seeds and the pollination of flowering plants .