Mumper was a pigeon in the Lower City of Corus in 246 HE. His feathers were dirty and greased on his wings and belly. That's why Beka named him Mumper.
In April and May of 246 HE he carried the ghost of a dead digger, who had been killed by Vrinday Kayu. He repeatedly appeared briefly in Terrier, often accompanied by other pigeons carrying ghosts. However, Mumper didn't appear in Bloodhound.