Birdhemoths were gigantic, intelligent birds capable of travelling between universes.
Coloth, after joining the Plume Coteries, (PROSE: Cobweb and Ivory) travelled with a birdhemoth steed called Rich, who was large enough to carry an entire city block's worth of people on his back. While they were travelling outside their native universe and passing through the 10,000 Dawns, Rich's wingbeat caused a "rogue wave of dimensional pressure" which led to a Galaxy Accident befalling the Sun of the beings of light's Dawn. Realising the subsequent plague of Invisible Infernos was somehow their fault, the two stayed in the Dawns, helping Dawn to deal with this crisis as well as others, including the destruction of Dawn 10000. (PROSE: Sonnenblumen)
Roger had heard from her family that before they changed their name to Bookkeepers, (PROSE: A Farewell to R.M.S.) the Plume Coteries (PROSE: A Farewell to Arms, et al.) traveled on the backs of majestic multicoloured birds. However, the only Bookkeeper she encountered in her lifetime instead travelled in "a boring metal sphere". (PROSE: A Farewell to R.M.S.)