The Factious, High-Drama World of Bird Taxonomy

(Andrew Jenner, Feb 28 2017)

In July 2008, an American ornithologist named Bret Whitney was researching antbirds in the Brazilian Amazon when he heard a curious bird song. The sound, to his expert ear, clearly belonged a Striolated Puffbird––a big, streaky creature that looks like an owl crossed with a kingfisher. But it also had a smoother quality that struck him as “off-the-charts different” from the slightly warblier songs he knew from elsewhere in the region.

Whitney recorded the bird and collected a specimen of this strange-talking bird. Before long, he was conducting an in-depth review of the species across its entire pan-Amazonian range. He and some colleagues published the results in a 2013 paper that proposed dividing the Striolated Puffbird into three distinct species, based on subtle vocal, morphological, and genetic differences between populations.

In due course, the matter came before the American Ornithological Society’s South American Classification Committee, or SACC, which exists to standardize bird taxonomy on the continent and sanction changes based on new science. Here, Whitney’s puffbird proposal met with mixed results. After debating the nuances of his research, the SACC endorsed his recommendations only in part: They split the westernmost group off into a new species called Nystalus obamai, but left two other populations as subspecies of the original N. striolatus.

Failing to see the logic behind this decision, Whitney regards it as “just nuts.” But it’s not unusual for things to get messy in the world of avian taxonomy, which addresses a fundamentally impossible task: the scientific imperative to label and sort amid the ever-evolving reality of life on Earth. An ostrich is definitely not a bald eagle, nor is a Canada goose a mallard. But the closer you zoom, the fuzzier things get. Are the Striolated Puffbirds of the western Amazon who stutter at the start of their songs different enough from other Striolated Puffbirds to merit full species status? What is a species, exactly, and where do the lines between one and another lie?

“We’re just trying to make the best of a bad situation. That’s all taxonomy is,” says James “Van” Remsen, the SACC’s chairman. Of the various “species concepts” in taxonomy that attempt to answer these questions, the SACC relies most heavily on the “biological species concept,” which basically defines a species as a group of things that only breed with each other. “We’re trying to apply artificial barriers on a continuum,” Remsen acknowledges. “It’s all kind of silly. … The emotions that are involved in some of these decisions are really kind of out of proportion.”

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