Birds can fly, walk, run, swim and dive. They occupy the air, oceans, fresh water, seashores, rainforests, deserts and polar regions. They have extraordinary colours and cryptic patterns that enable them to be well camouflaged. Worldwide there are around 10,000 species of birds of which over 700 occur in Australia.
Birds are warm-blooded vertebrates with feathers. This easily distinguishes them from all other living animals. Other easily observed features include:
- forelimbs modified as wings
- jaws lacking teeth and with a horny cover
- they walk on their two hindlimbs
Although birds cannot be mistaken for any other living group of animals, the line between birds and non-birds is much less distinct if fossil animals are examined. Many characteristics that distinguish birds from other living vertebrates first arose in certain groups of dinosaurs. For this reason, many scientists believe that birds evolved directly from these dinosaurs.