What ARE birds?

As a general statement, yeah, "Are birds ______" is definitely a snowclone.

In regards to this, apparently far too specific topic; however,

Snowclones are not animals or species therefore

• Snowclones are not birds!
  

Hint:

• Australian ghost sharks are birds.

I really hope someone will defeat this (possibly too-biology themed) topic. I recommend using the google as I did when figuring out what the heck a "snowclone" was. I figured it was a good idea but I do get paid money to teach people biology so I may have a bit of a bias.