"Actually, he says he prefers to be called Hawk." - Beck translating for Cousin Dove
Cousin Dove is a dove that filled in for Brother Dove in Four Clues for Rani. He likes to be called Hawk even though oddly enough he is afraid of hawks. His feathers have a more pink hue to them and he appears to be younger than Brother Dove.
In the books
In Four Clues for Rani, after Brother hurt his wing Cousin Dove was called in to help Rani. He flew Rani and Ronan where ever they had to go for the Fairy Treasure Hunt. But when Rani was attacked by a hawk, he flew away. At the end he comes back and feels bad for leaving them.