In Genesis, Noah sends out a dove that returns with a freshly plucked olive leaf. This occurs after the raven has already been released and after Noah waits through another interval. The leaf tells Noah that the floodwaters have receded enough for vegetation to be visible.
Noah sends the dove out more than once. On its first release, it finds no place to rest and returns to the ark. On the next release, it comes back with the olive leaf. When Noah sends it out again, it does not return, indicating that the land is becoming habitable.
The dove and olive leaf are often treated as a universal peace emblem, but their immediate function in Genesis is practical: they report changing conditions outside the ark. The passage also distinguishes this dove from the raven, which Noah releases first.
Later art, literature, and political symbolism made the image famous well beyond the flood narrative. The canonical answer to the bird question, however, is simply a dove.