
1) Birdwatcher
Found on
https://www.crosswordclues.com/clue/twitcher

A birdwatcher who is obsessed with list-keeping. Generally, a twitcher is obsessive of their life-list, going to great expense and effort to add new species to the list. They also tend to have several “important’ lists going at any one time, such as a year list and a country list. Twitchers invariably have huge lists that only impress other twi...
Found on
http://birding-world.com/glossary-birdwatching-slang/

one who regularly goes chasing after rarities
Found on
http://birding-world.com/glossary-birdwatching-slang/

Obsessive list-keeping birder who goes after rare birds found by other people. Twitchers might cross half the country overnight to see one little nondescript bird sitting a kilometre out on a windswept beach. Twitchers all have huge lists that only impress other twitchers. Surprisingly, they are not always good at identifying birds, because they le...
Found on
http://birding101.co.za/newbirder/birding-terms/

An obsessive birder who goes to great lengths to observe rare birds.
Found on
http://earthdesign.ca/dict.html

• (n.) One who, or that which, twitches.
Found on
http://thinkexist.com/dictionary/meaning/twitcher/

Twitcher is British slang for a bird watcher, especially an over-enthusiastic one.
Found on
http://www.probertencyclopaedia.com/browse/ZT.HTM

British slang for a bird watcher, especially an over-enthusiastic one.
Found on
https://www.easypacelearning.com/english-books/slang-words-a-to-z/375-slang

A person who will apply unusual effort or expense to see a rare bird they have not seen before, their hobby.
Found on
https://www.sciencebase.com/science-blog/birding-glossary.html
No exact match found.