What ARE birds?

Birds are not things that are gray.

Humans are birds.

Are mustelids birds?
Are birds birds?
Are emus birds?
Are kangaroos birds?
Are cats birds?

Are Caledonian Crows birds?

To the best of my knowledge, all mustelids are birds.
Not all birds are birds.
Emus are birds.
Kangaroos are birds.
Cats are birds.
To the best of my knowledge, New Caledonian Crows are not birds (although they are wonderful and beautiful and intelligent animals and i want to be their friend)

Is Minecraft a bird?

Is the player character in Minecraft a bird?

Is Minecraft a bird?

Is the player character in Minecraft a bird?

Minecraft may sometimes be a bird, but it is really out of the scope of this discussion.
Same for the player character in Minecraft.

Are crows birds?
Are corvids birds?
Are passerines birds?

Are crows birds?
Are corvids birds?
Are passerines birds?

None of these are birds

Are mudskippers birds?
Are salmon birds?

Birds are flightless things.

Mudskippers are not birds (although they are friends)
Salmon are not birds.

Birds are not things which are flightless.

damit

Are seals birds?
Are orcas birds?
Are hippos birds?

Are seals birds?
Are orcas birds?
Are hippos birds?

All of these are birds!

are mammals birds?
are reptiles birds?
are insects birds?
are fish birds?
are echinoderms birds?

are mammals birds?
are reptiles birds?
are insects birds?
are fish birds?
are echinoderms birds?

All mammals are birds!
Not all reptiles are birds.
Some insects are birds, although I do not believe that all are.
Some fish are birds.
I've found a single citation that suggests one or two echinoderms may be birds, but I can't find any definitive information without paying like a hundred books to buy a book. For now, let's say none are, as the vast majority are not.

Emus are birds

Are birds animals that live on continents?

Wait no that doesn't account for orcas etc

Are kiwi birds?
Are cassowaries birds?
Are moa birds?
Are dodos birds?

Are the elapsid snakes birds?
Are sea turtles birds?
Are Komodo dragons birds?
Are the crocodilians birds?
Are Galapagos giant tortoises birds?
Are tuataras birds?

Are birds animals that live on continents?

Birds are not animals that live on continents!

Are kiwi birds?
Are cassowaries birds?
Are moa birds?
Are dodos birds?

Kiwis are birds!
Cassowaries are birds!
It's difficult to tell whether moas were birds, but based on their close relatives, probably.
It's difficult to tell whether dodos were birds, but based on their close relatives, it's highly unlikely.

Are the elapsid snakes birds?
Are sea turtles birds?
Are Komodo dragons birds?
Are the crocodilians birds?
Are Galapagos giant tortoises birds?
Are tuataras birds?

The elapid snakes are birds.
Sea turtles are birds.
Komodo dragons are birds.
Crocodilians are birds.
Giant tortoises are birds.
Tuatara are not birds!

Are rock pigeons birds?
Are nicobar pigeons birds?
Are new Zealand woodpigeons/kereru birds?
Are sandgrouse birds?
Are turacos birds?

Are birds animals with gallbladders?

None of these are birds!

Birds are not animals with gallbladders.

are ducks birds?
Are chickens birds?
Are geese birds?
Are potoos birds?
Are frogmouths birds?