(covers information from several alternate timelines)
In 2258, in the alternate reality, Cadet Uhura heard a transmission which reported that forty-seven Klingon Warbirds had been destroyed by a single Romulan ship, which was later identified as the Narada, when it had attacked a Klingon prison planet.
During the same year, Klingon Warbirds were also part of the Kobayashi Maru scenario. These simulated Warbirds were capable of cloaking, had shields, and were armed with photon torpedoes. During James T. Kirk's third attempt at the scenario, two of five of these vessels entered the neutral zone before locking weapons on the USS Trainer, captained by Kirk. Moments later, the three other Warbirds decloaked while targeting the Starfleet craft, and then began firing torpedoes as they simultaneously maintained shields. After the simulation was affected by a subroutine that Kirk had secretly inserted, the shields of the Warbirds were suddenly eliminated, and the Klingon vessels were all vulnerable to a single photon torpedo strike each. (Star Trek)
The term was also included in the first draft script of DS9: "When It Rains...". In that teleplay, Gowron notified Admiral Ross and Captain Sisko that he planned to send "a swarm of Klingon warbirds" to bombard Cardassia, thereby ending the Dominion War.
The use of the term "Warbird" in relation to the Klingons, as used in ENT: "Broken Bow", was a writer's error. Soon after the episode's production, Brannon Braga stated, "We made one mistake where in the pilot we called the Klingons' ships Warbirds, when in fact the Romulans use Warbirds and Klingons use the Bird-of-Prey. There was nothing we could do about it, and I'm sure we're going to get a lot of angry fans. But it was an honest mistake." (Star Trek: The Magazine Volume 2, Issue 9, p. 20) In the second draft script of "Broken Bow", these ships were actually referred to as "war ships" rather than "Warbirds".
The Warbirds in Star Trek were designed by John Eaves. In a scene deleted from the film, after the Narada is disabled by the USS Kelvin's attack, a fleet of ten Klingon Warbirds decloak and surround Nero's ship.
The 1993 adventure video game Star Trek: Judgement Rites mentions the existence of a Klingon Warbird as part of a museum exhibit at the Smithsonian Institution Annex on Nova Atar III. This is the earliest mention of the Klingons employing the term warbird, 8 years prior to Broken Bow and 16 years prior to the Kelvin Timeline's first Star Trek movie.
In 2009 Burger King released Star Trek toys as part of their kids meals, including a Klingon Warbird as one of the toys.
An Eaglemoss special edition issue feature a extra large model of a Klingon Warbird.