It turns out a twitcher is a bird watcher of the rare variety. They travel around the world looking for rare birds and adding the name to their list of said rare birds seen. It is a kind of rare competition I think. The article in Lonely Planet had some comments from people that I wouldn't want to meet...sort of mean and cross. Evidently LP offended them in some way! Bird watcher really need for those of us that don't (watch birds) to straighten up.
However, since I live with a Dr. Doolittle that loves birds, I have had some pretty unusual experiences with our feathered friends. See, my husband is the kind of guy that can get a bird to sit on his finger if he wants. When we sit in the back yard he calls the hummingbirds and they come to the feeder to drink as we watch them. Their clicking can be heard as soon as we open the door. They will come in our park model living room in Arizona. If our bedroom window is open they will fly to the window to look at us.
We had a mourning dove come sit on our front porch in Arizona after a Road Runner had eaten her babies. We had chased the carnivorous bird away from the nest several times. She was sure my husband could get them back I think. It broke my heart.
On the other hand, we would never travel anywhere to find a bird. I don't think either one of us actually believes that we could find the birds. Besides, why would be do that when the birds come to us? And, honestly, bird watchers that are very serious scare me a little bit. Especially if they are a twitcher.