Although BIRD supports all the commonly used routing protocols, there are still some features which would surely deserve to be implemented in future versions of BIRD:
If you use BIRD, you're welcome to join the bird-users mailing list (bird-users@network.cz) where you can share your experiences with the other users and consult your problems with the authors. To subscribe to the list, visit http://bird.network.cz/?m_list. The home page of BIRD can be found at http://bird.network.cz/.
BIRD is a relatively young system and it probably contains some bugs. You can report any problems to the bird-users list and the authors will be glad to solve them, but before you do so, please make sure you have read the available documentation and that you are running the latest version (available at bird.network.cz:/pub/bird). (Of course, a patch which fixes the bug is always welcome as an attachment.)
If you want to understand what is going inside, Internet standards are a good and interesting reading. You can get them from ftp.rfc-editor.org (or a nicely sorted version from atrey.karlin.mff.cuni.cz:/pub/rfc).
Good luck!