how conservative is the AOU checklist?
It seems to me that the NACC is really quite conservative, and sometimes I appreciate that. I happen to agree that such species level splits as the Herring Gulls are not sufficiently supported to accept at this time. However, their higher level taxonomy seems to be lagging behind current knowledge so much that it could be seen as quite misleading as regards what we know about the evolutionary history of birds.
Case in point is the decision to separate the falcons and the 'other raptors' into distinct orders, but then leave them side-by-side in checklist sequence. The proposal for this relies heavily on genetic studies by Ericson et al. (2006) and Hackett et al. (2008) that are in agreement that the falcons belong in a larger group with the Passeriformes, Psittaciformes & Cariamidae (which should be in the Cariamiformes, of course). So why, if they accept these studies as evidence to split the orders, have they not placed these groups (including the parrots) in the appropriate sequence in the checklist? Are they really not convinced, or are they just trying to avoid upsetting people who are comfortable with the old (albeit incorrect) sequence?