Classifications are dynamic sets of hypotheses about population dynamics and evolutionary histories. They are subject to regular revision based on new published research, not static lists for implementation. The current revolutions in avian taxonomy challenge us to maintain an up-to-date classification of world birds. We are in a period of major transitions in the application of evolving species concepts and DNA-based phylogenies. Changes of classification and dramatic increases in the number of species recognized on major world lists are underway. We also are in an era of unprecedented participation, published productivity, and real time provisions of new information.

We  now have the ability to to distinguish taxa of similar rank that are reciprocally  monophyletic. This lets us redefine some groups of species that in hindsight were paraphyletic. Changes in taxonomy follow, especially realigning of orders,  families, and genera to define monophyletic taxa that can be reconnected to  their closest relatives in the classification. Genera also change with corrections of nomenclature and the rules of priority. As a result, we can expect ongoing changes of working classifications for a decade or so.  Continually improving sets of DNA sequences and analytical approaches  will override previous conclusions, so cautious revisions of higher category taxonomy and new sequences of taxa will be prudent.

Excellent  resources on the higher classification of birds include Joel Cracraft’s (2013) Avian higher level relationships and classification in Howard & Moore 4, Jon Fjeldsa’s (2013) Avian Classification in Flux in HBW Special Volume and  John Boyd’s website Taxonomy in Flux. For comprehensive views of the relationships among Orders, see Rick Prum et al’s (2015) A comprehensive phylogeny of birds (Aves) using targeted next generation DNA sequencing, and Erich Jarvis et al’s (2014) Whole genome analyses resolve early branches in the tree of life of modern birds.