[CT Birds] More AOU taxonomy talk

paul cianfaglione pgcianfaglione at gmail.com
Wed Jul 25 15:08:38 EDT 2012

This information was gleaned (letter and response) from the latest edition
of Birding Magazine. Some of you may find this interesting.

Paul Cianfaglione

The AOU Check-list: Humbleness? Hubris? Hypocrisy?

For now, most birders and the ABA are content to be sheep and follow the
proclamations of the American Ornithologists Union (AOU) about what is, and
what isn’t, a species – and thus can be counted on a list. It’s just easier
that way, even if some of the AOU’s decisions are ill-founded or
inconsistent. But if the AOU were your dentist or hairdresser, would you go
back to them?

One of the more puzzling things in recent AOU proclamations and checklists
has been the introduction of the category “incertae sedis” in their
checklists meaning “of uncertain placement.” Yes, the AOU is actually
saying, and often despite genetic analysis, that they don’t know where a
few groups of birds fit in the overall classification. At first this
gesture might seem like humility, but the obverse is that the AOU is
implying they really do know where all the other birds do belong.

Of course, a quick perusal of the regularly published AOU taxonomic updates
over the last 20 years shows that major changes happen all the time. Those
changes extend well beyond the occasional genus of “uncertain placement.”
Often, they involve major changes to avian relationships that were “known”
to be “true.” Why not be honest and just write “incertae sedis” at the
start of every checklist and be done with it?

Steve Howell



Other than finding another outlet for hurling his predictably volcanic
invective at the AOU, Howell’s major point is evidently that no one,
including the AOU, knows “where birds belong.” That point was arguably
valid a couple of decades ago, before DNA-sequencing technology and
analyses, but all classifications explicitly contained varying degrees of
uncertainty and were best treated as hypotheses. However, unless Howell has
an alternative explanation-of which the world is yet unaware-for the
mechanisms of inheritance and the interpretation of DNA sequence data, then
“we” actually do “know” where most groups of birds belong with an
unprecedented degree of certainty, and Howell’s statements contain an
exceptionally unfavorably arrogance-to-ignorance ratio. The monophyly
(namely, that all members share a common ancestor) of the overwhelming
majority of orders and families of North American birds has been
corroborated by multiple independent genetic data-sets. Those taxonomic
changes to which Howell refers are in response to those data.

There remain, however, a few groups of uncertain familial placement-also
known as incertae sedis. This placement is not “despite” genetic analysis,
as Howell states, but rather because of them, and we are likely only a few
analyses away from certain placement of the few taxa currently listed as
incertae sedis- for example, the saltators and the Bananaquit. We are also
in the process of transferring blocks of genera among the Emberizidae,
Thraupidae, and Parulidae. A few others, such as the not-a-real-warbler
Yellow-breasted Chat, will likely spend time in incertae sedis until new
data reveal where their branches join in the avian tree. Incertae sedis
acts as a holding pen for those taxa for which new data indicate that they
do not belong where previously placed but are still ambiguous as to where
they really do belong.

It’s only fair to extend Howell’s smug choose-your-dentist-wisely analogy
to some of his own taxonomy. For example, Howell’s own (A Guide to the
Birds of Mexico and Northern Central America) data-free treatment of
Worm-eating and Swainson’s warblers as members of the same genus-despite
their radical differences in song structure, nest architecture and
placement, and foraging behavior-would now require of all warblers except
the Ovenbird into that genus to make it monophyletic. Would you go back to
that dentist?

Van Remsen

Member, AOU Committee on Classification and Nomenclature of North and
Middle American Birds

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