Exercise 2 solution

(a) Birding: the term some people prefer because it includes listening to birds. Kind of activity, not a person.
(b) Twitching: the British term for pursuing a previously located rare bird. The North American equivalent is often "chasing".
(c) Birder: the dedicated enthusiast (the usual North American word).
(d) Twitcher: a person who travels long distances to see a rare bird and count it on a list.
(e) Ornithologist: someone who studies birds by formal scientific methods; most birdwatchers do it for recreation or social reasons instead.

Sample sentence: "I drove four hours to twitch a rare bird that a local birder had found that morning."