who fails to see a rare bird has dipped out; if other twitchers do see the bird, they may feel gripped off. Suppression is the act of concealing news of a rare bird from other twitchers.

Many birders maintain a life list, that is, a list of all of the species they have seen in their life, usually with details about the sighting such as date and location. The American Birding Association has specific rules about how a bird species may be documented