Great suggestion!!! I actually changed it so that I took out four uncommonly known birds and added some more commonly known ones. There are still some great obscure ones in there for those Birders out there!
All the ones you mention are all excellent suggestions but mostly obscure and when you only have 99 birds as answers, you have to narrow them down. To keep the quiz enjoyable for the general public I tried to go with more commonly known birds with only a few obscure ones. Swallow IS one of the answers though!!
Nightingale not nightengale. And what about the tits? There are so many species and they are so common that it seems strange to have kakapos but not them.
"Bluebirds" are indeed a species. Scientific names of Sialia sialis, Sialia mexicana, and Sialia currucoides refer to the Eastern Bluebird, Western Bluebird and Mountain Bluebird consecutively