My apologies if there are past discussions on this subject - I did a short search and couldn't find any. I am trying to understand the similarities and differences between ebird and avibase. I had thought they were possibly competitors for the same user, but they do appear to have some sort of complementary relationship. I'm not really asking whether one is "better" than the other, rather, I'm trying to understand if they are the same sort of program, or cater to different nationalities, or whatever. It's possible that their relationship is generally well understood, but somehow I've missed it!