"Twitcher" is a term most commonly associated with bird watchers; however there are several synonyms that one can substitute for the word. For instance, "birder" or "ornithologist" are commonly used words in the bird watching community. Other less common synonyms include "bird fancier" and "aviphile". "Twitch" has also been used to describe bird watchers who are often searching for rare or noteworthy sightings. The term "killer" has been used in a more competitive context, often associating bird watching with a race to tick off as many species as possible. Nonetheless, all of these words are used to describe individuals who share a passion for and enjoyment of birds, their behaviours and their habitats.