The 18'000 bird species thought to exist today, a number which just recently increased from 10'000, belong to the Class Aves. Birds belong to the Class Aves and have the following, among other, characteristics in common: They are vertebrates carrying a back bone, use feathers for insulation, are warm-blooded, use wings mostly for locomotion and are egg-laying.

There are an estimated 10'000 species worldwide. However, a recent study by Barrowclough based on morphological and genetic differences suggest this numbers has to be almost doubled, reaching about 18'000 species!

Landbirds (Overview)

Seabirds (Overview)

Penguins (Overview)