Blood ravens are Balborite messengers. Blood ravens have been trained and bred by the Balborites for thousands of years.
Blood ravens are highly intelligent scavengers and can be trained to deliver messeges over long distances. Both male and female birds have have a distinctive tuft of red feathers on their heads.
Bird messengers are widely used as the preferred method of communication on Durn. The only race that does not use bird messengers is the orcs. Any trained spellcaster can use a bird messenger, with pigeons being the easiest to train and control. However, bird messengers are used and trained all over the continent by non-spellcasters as well. In exchange for their work, they will be rewarded by their handlers with food; Skera-Kina offered her blood raven the eyes of her dispatched victims, but people other than Balborites have been known to feed messenger ravens with the remains of fallen enemies as well.
A variety of dfferent birds are used by spellcasters, with ravens and falcons being the favorites for their speed and intelligence. They are also preferred because they are not a prey species, and there is always a possibility that a pigeon or smaller bird will be subject to predation.
"Overhead, a giant blackbird flew silently. Tallin froze. The bird had a red tuft of hair on its head—a blood raven. There was no mistaking it; this was a Balborite messenger." - Return of the Dragon Riders, Book 2.