Warbeak was a female Sparra, the daughter of Greytail and Dunwing and niece of King Bull Sparra. Though being royal family, Bull regularly forgot his promise to look after Warbeak and her mother following Greytail's death at the fangs of Asmodeus, but they got along quite well, with Warbeak becoming a popular, intelligent and a powerful warrior as the years went by. Warbeak also developed the habit of identifying creatures from below as "worms".
During the quest for the Sword of Martin the Warrior, Jess Squirrel, after receiving intelligence on its probable location, climbed up to Redwall Abbey's roof to retrieve the sword from is place in the abbey's weathervane (unaware that sparrows had stolen it some years back). It was here Warbeak and a team of Sparra Warriors attacked Jess, and almost succeeded in throwing her off the roof, but timely assistance from Matthias and Basil Stag Hare saved her, as they shot a continuous hail of arrows that forced the Sparras to stand down. One of Matthias's arrows impaled Warbeak through the leg and she fell towards the earth but was saved by Matthias. She was imprisoned when she became hostile, though she refused to give up any information.
Needing intelligence on the sword's location, Methuselah used his knowledge of the Sparra culture to trick her into revealing Bull's theft of the sword from the weathervane, and as such, bribed her with candied chestnuts, which semi-convinced her to help Matthias reach the Sparra court. Along the climb, Warbeak unsuccessfully attacked Matthias and he retaliated by pushing her off the edge of a red sandstone ledge (Warbeak had a brick toggle around one of her legs to prevent her from flying away) and held on to the collar he had put on her, and threatened to drop her unless she promised to behave. Not having any other options except death, Warbeak agreed. They eventually became friends on the long climb.
Upon entrance to the court, Bull initially ordered Matthias to be put to death, but timely intervention of Warbeak and Dunwing (who learned Matthias had saved her beloved daughter) kept him alive and placed in Dunwing's custody. Later, when Bull continuously refused to let Matthias leave the court, Dunwing arranged for Bull and all of the Sparras to leave for the Quarry, while Warbeak helped Matthias escape, stealing the sword's scabbard in the process.
When Bull was killed by a fall from the roof (during his attempt to stop Matthias from escaping), Dunwing elected Warbeak to succeed him, to which the entire Sparra population agreed, and Warbeak became the youngest-ever Queen. Warbeak was an excellent and beloved ruler to her people, and had them keep watch over the Abbey's war with Cluny the Scourge.
When Cluny was poised to seize the Abbey, Warbeak and a team of warriors left for the Quarry to warn Matthias, who by this time had succeeded in killing Asmodeus and stealing the sword. Warbeak then gathered the entire Sparra tribe, numbering 1000 warriors, and combined with the 500 shrews of the Guosim, retook Redwall from Cluny's army (Cluny was slain by Matthias). Warbeak decided to interact more with the Redwall creatures, such as regularly being educated in new cooking methods from Friar Hugo.
Eight seasons later, while Matthias, Basil Stag Hare and Jess were away tracking down Slagar the Cruel after their young ones' kidnapping, Redwall's monks discovered crucial information, including a map, that could aid in Matthias's pursuit, and Warbeak was convinced to order her entire tribe to go off in all directions in separate groups with copies of the information, for the purpose of delivering it to Matthias (this, coupled with General Ironbeak's invasion of the court, nearly wiped out the Sparra tribe).
Warbeak's team was the one that found Matthias, who by this time was locked in combat with the Longtail Horde. Warbeak and the Sparras came to their friends' defense and fought and defeated the Longtails. Although, during the battle, Warbeak was hit by a stray arrow and died. Matthias was greatly saddened by the death of his friend, and the next day, promised at her grave that he would never forget her.