These are cockatiels. Cockatiels are a kind of cockatoo and parrot that live in Australia. They are a very popular pet bird. We saw these birds at Petco.
You can tell how a cockatiel is feeling by looking at the crest of feathers on top of its head. If the feathers are up, the cockatiel is surprised or excited. If the feathers are down flat on its head, the bird is mad or defensive. If the feathers are in between, then they are relaxed. The ones in these pictures are a little upset because we were staring at them and taking their picture.
Cockatiels with red cheeks are grownups. The gray ones in this picture are juveniles.
Some day I hope we get a pet bird at my house. Maybe a cockatiel.