C.E. Evans wrote:
I really hate that the Enterprise writers were too stupid to remember that "warbird" referred to one specific Romulan vessel in TNG, and now we're stuck with it as a Klingon reference.
The design is also referred to as a Klingon warbird in Star Trek XI.
John M. Ford's The Final Reflection
refers to Klingon ships as "Warbirds" way back in 1984.