Beavers are muscular, brown animals with bristly fur and beady, dark brown eyes. This species first appeared in The Fourth Apprentice. They love water and have webbed, clawed feet and a flat tail to swim. They are equipped with powerful teeth used to cut down trees for dams, and for self-defense. One beaver killed a RiverClan warrior, Rippletail, by severing an artery located in the shoulder with it's teeth, causing the young cat to bleed to death. Despite their rivalry with Clan cats, they eat only plant matter. According to Erin Hunter, they were introduced into the lake territory so that wildlife observers could document their progress with deforestation for the purpose of building the dams. This is similar to how deforestation occured in The New Prophecy. They will return in the other books of Omen of the Stars and will likely play a major role closer to the lake, because Erin Hunter has revealed that a warrior will be injured by a fallen tree in Fading Echoes.