........... The new 'Birds of Australia' has a similarly useless index listing birds by their first name rather than by group. I do hope its not part of an international trend!
I suspect it's the easiest way to compile an index. No manpower needed, just a small program. And many of those who do the printer's job are no birders anyway. Nevertheless, there are obviously birders at the beginning of such a book. They definitely need to follow through till the end, or else the blame will rest on them.