What ARE birds?

Are manta rays birds?
Are electric eels birds?
Are flying squirrels birds?
Are komodo dragons birds?
Are salamanders birds?

Manta rays are not birds.
Electric eels are not birds.
Flying squirrels are not birds.
Komodo dragons are not birds.
Salamanders are not birds.

Are cougars birds?
Are mountain lions birds?
Are reptiles birds?
Are marsupials birds?
Are extinct vertebrates birds?

Cougars are not birds.
Mountain lions are birds.
Reptiles are not birds.
Marsupials are not bids.
Extinct vertebrates are not birds.

Are geese birds?
Are white-headed woodpeckers birds?
Are tabby cats birds?
Are axolotls birds?

Geese are not birds.
Woodpeckers are not birds.
Tabby cats are in that same problem as the fish.
Axolotls are not birds but it would be fun.

Killer Whales are birds.