Albatrosses are sea birds that can be seen as both good and bad omens, depending on how the bird is treated. At one time, sailors thought that being followed by an albatross was a good omen, and typically, albatrosses are only seen as bad luck in that it is taboo to kill them.
It is the act of killing the bird rather than the bird itself that is considered to be bad. This can be seen in Samuel Taylor Coleridge's poem "The Rime of the Ancient Mariner." However, this taboo didn't keep real-life sailors from killing albatrosses and using them for their meat, feathers, feet and bones.