The Factious, High-Drama World of Bird Taxonomy

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.”

It doesn’t help that this is an era of rampant splitting. Taxonomists, generally speaking, draw boundaries between bird species more narrowly now than in decades past, and improving technology—e.g., recording equipment more easily deployed to the remote Amazon—provides ever more opportunity to scrutinize differences between bird populations. The entire South American list has grown by around 160 species since the SACC was formed in 2000––the vast majority resulting from splitting something like the Striolated Puffbird into two or more species. (Though every once in a while, scientists still do stumble across something entirely new.)

Once N. obamai, the former member of the Striolated Puffbird club, had been inaugurated to full species status, the SACC turned its attention to corollary issue: what to call the bird in plain old English? And what about the birds still known as N. striolatus? Ideal bird names, Remsen says, are “uniquely descriptive yet evocative at the same time.” South America hummingbirds provide some wonderful examples: Violet-capped Woodnymph, Horned Sungem, Hyacinth Visorbearer, Booted Racket-tail, Blue-tufted Starthroat.

“These names are exotic and amazing,” says Alvaro Jaramillo, a California-based ornithologist and member of the SACC. Jaramillo leads birding tours and spends a lot of time with the hobbyist birders who are everyday users of common names. He believes in a name’s power to enchant. “You want to see [these birds],” he says. “When a name can be evocative that is a real benefit.”

But agreeing on names that do a bird justice and leap off the field guide page is no easier than species classification. A great many birds are named for conspicuous features, like the Red-winged Blackbird’s brilliant red wing patch. The Striolated Puffbird itself belonged to this school of naming thought; “striolated” means “striped.” Unfortunately for SACC, the low-hanging fruits have pretty much all been picked. Species like the Striolated Puffbird that are split primarily based on vocal analysis usually look almost identical, vexing the general birding public and the naming authorities. In the case of these new puffbirds, the SACC considered “Stuttering” (obamai) and “Whistling” (striolatus) Striolated-Puffbird––replacing visual descriptors with aural ones––but couldn’t reach a consensus. (The 10-member SACC operates on a one-man, one-vote system, with any proposal requiring a two-thirds majority to pass.)

The patronym “Natterer’s Puffbird” was also suggested for striolatus, a nod to the 19th-century Austrian naturalist Johann Natterer, who collected the first Striolated Puffbird specimen (as far as Western science is concerned) during the nearly two decades he spent in South America. But this didn’t muster the votes to clear committee either, and the SACC eventually fell back on geography, a third major current within bird naming. Since these species’ ranges don’t align well with existing political or ecological boundaries, the SACC had to keep it basic: Western Striolated-Puffbird for obamai, Eastern Striolated-Puffbird for striolatus.

“Scientists have seen it as kind of their duty to make the kind of names you’d introduce to your parents, but not the kind of names you’d party with,” laments Jaramillo, who voted for the Stuttering and Whistling options.

Perhaps because the lines between species are so blurry, the project of naming birds at times degenerates into internecine squabbling over more black-and-white matters of English usage and grammar. The hyphen in Striolated-Puffbird, for example, is highly controversial within avian taxonomy.

The SACC is officially pro-hyphen, arguing that the mark serves two functions. It resolves potential ambiguities in names like Eastern Striolated-Puffbird (i.e., this bird is a Striolated Puffbird of the east, not a puffbird with eastern striolae). And it signifies the close taxonomic relationship between species (i.e., the two Striolated-Puffbirds are more closely related to each other than they are to the twenty-some other puffbird species in South America). Then there’s the International Ornithological Congress, or IOC––an entirely separate group that maintains its own checklist, conducts its own review of bird taxonomy, and states on its website that “grammarians now view past enthusiasms for hyphens as excessive and unnecessary.”

The SACC and its North American sister, the NACC, are standing committees of the American Ornithological Society, which sticks to the New World. The IOC is just one of four major checklist systems with a global purview. From the outside, the distinctions between them are fairly trivial. But as one might imagine, among those whose careers are built upon the minutiae of this stuff, feelings can run high.

After, the IOC checklist founder Frank Gill published a case against hyphens, for example, Remsen posted an acerbic pro-hyphen rebuttal on the SACC website. The rebuttal is twice the length of this story.

The bodies also diverge in matters of orthography. Where the SACC uses “gray,” the IOC prefers “grey”; while the SACC permits the occasional tilde in Spanish and Portuguese place names, the IOC only allows umlauts in patronyms. Sometimes they even disagree on the underlying taxonomy. The SACC is a more conservative body, less willing to confer upon a group of birds a species-level designation.

In the recent puffbird case, however, both groups accepted the obamai split and differ only in that the SACC checklist hyphenates Striolated-Puffbird while the IOC list does not. Like the SACC, the IOC has also left as subspecies the other two populations that Whitney believes merit species status. Whitney maintains that the rationale used to split off obamai––primarily, those nuances in vocalization that ornithologists increasingly view as a critical indicator of avian species boundaries––should also apply to the other two subspecies.

But for now, the taxonomic powers that be have spoken. After the painstaking field research, the vocal analyses, the specimen collection, the DNA comparisons, the peer review, an exacting scientific process can culminate in a judgment call. “There are sets of researchers with an opinion that ‘this is enough’ [to call something a species], and there are others that don’t have that opinion,” Whitney says. “We’re basically in this tug-of-war.”

The SACC checklist now stands at 3,376 species. But don’t bother committing that figure to memory. In the clamorous world of avian taxonomy, one thing that everyone can agree on is that there are many more species splits to come, and many more names to choose.