From watching twitter to bird watching...
Twitcher: A type of bird watcher who seeks to add as many species as possible, willing to go to great lengths to see any bird species they haven't previously recorded.
It originated in 1950s when it was used for the nervous behavior of Howard Medhurst, a British birdwatcher.
It appears there is a bit of a divide between bird watchers and twitchers. Bird watchers tend to think of twitchers with having poor birding ethics.
Did you know "twitch" was considered as a name for Twitter before it was called Twitter?