The Archaeopteryx is a very early bird, now extinct. 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.