City Wilds: Of songbirds and passerines

On a recent walk with Jan through Ruth Arcand Park, I noticed a red-breasted nuthatch perched atop a spruce. The small talkative bird called loudly in its nasally way: Yank-yank-yank-yank, on and on. I told Jan that I thought the nuthatch might be in mating-season mode, either calling for (or to) a partner, or announcing his territory to competitors.

That prompted Jan to ask, “Do nuthatches sing?”

“Not really,” I replied. “It’s a songbird that doesn’t really sing, though it has a variety of calls.”

After a moment or two, Jan asked a follow-up question, which went something like this: “If not all songbirds sing, then what defines a songbird?”

“Good question,” I replied and I thought for a while and couldn’t come up with a good answer.

Our conversation eventually expanded to passerines, a group of birds that I inaccurately (but understandably) equated with songbirds. But again I couldn’t say what distinguishes passerines from non-passerines.

The fact that I’ve loved, studied, and learned the identities and lifestyles of songbirds for nearly three decades, but couldn’t easily share their defining characteristics surprised me—and embarrassed me just a bit. So much for my naturalist store of knowledge.

After a couple of stumbling attempts, I simply admitted my ignorance—that in itself suggests some personal growth—and shrugged, “we’ll have to find out.”

And so we did.

I’ll begin with passerines, which in scientific lingo belong to the avian order “Passeriformes,” a group that includes all songbirds but other types of birds as well. In essence passerines are perching birds.

According to an online article I found in the Proceedings of the National Academy of Science (PNAS), their numbers include more than 6,000 species, or more than 60 percent of all avian species alive today.

I found some additional—and easy to digest—information about passerines on thespruce.com, which happens to be a home-improvement-oriented website that offers “practical, real-life tips and inspiration to help you make your best home,” or put another way, “spruce up your home.”

I never would have imagined such a site might offer insightful information about passerines, but it does, once again demonstrating it helps to be broad-minded when doing research; and you never know who or what might become your teacher.

I will note that some of the passerine information I found on The Spruce appears to be either outdated or not quite right (at least if you believe PNAS and other scientific and birding sources). But I will also add that I searched several bird- and conservation-oriented websites for a straightforward discussion of passerines before I turned to The Spruce. And its basic information about passerines seems accurate, that I’ve been able to determine from other sources I’ve checked.

All that noted, here’s the gist of what I learned from the website (and backed up from bits of information from other sources): “The most prominent characteristic shared by all passerine birds is the anisodactyl arrangement of toes: three toes facing outward and one backward, which allows the bird to easily cling to both horizontal and nearly vertical perches, including branches and tree trunks. These birds also have an adaptation in their legs that allows them extra strength for perching. In fact, the relaxed position of their feet (allows them) to perch even when sleeping. It is this toe arrangement and gripping posture that makes all passerines perching birds.”

The Spruce further notes that many passerines also use their feet for other purposes: preening their plumage, holding seeds or nuts while prying apart shells, gripping nesting materials and building nests. And some birds, most notably those clever corvids, may use their feet “to grip twigs, sticks, or rocks to be used as rudimentary tools.”

To be honest, just about all the prime examples of passerines that I could find online (whether The Spruce or other websites) seem to be what I call songbirds. But I’ll accept that some other types of birds also qualify.

A partial list of birds with Alaska connections that are not passerines apparently includes these: hummingbirds; woodpeckers; kingfishers; eagles and hawks and other raptors; ducks and geese and other waterfowl and seabirds; sandpipers and other shorebirds; gulls and terns; and ptarmigan and grouse.

Next, songbirds. For this category, I’m happy to report that a familiar birding website, that of the National Audubon Society (www.audubon.org), provided just the information I needed. Though it wasn’t entirely simple to digest.

Here’s some of what I learned. First, not all songbirds sing. As already mentioned, the red-breasted nuthatch is evidence of that, and so are the corvids with which we share the Alaskan landscape: ravens, crows, magpies, and jays.

As Audubon magazine reporter Corryn Wetzel asks, “If singing ability doesn’t make a songbird a songbird, then what does? The question is actually a lot trickier to answer than it might seem.”

Which means I don’t have to feel so bad about not knowing the answer (or remembering it, if I’d been taught the answer once upon a time).

To begin, all songbirds are passerines, which as we’ve just learned, means they are perching birds. They belong to the suborder “passeri” and in scientific lingo are called oscines. That is, oscine equals songbird. According to Wetzel (and thus Audubon), more than 4,000 species of oscines inhabit the world. Which also means that some 2,000 other passerine species that aren’t songbirds exist. So why can’t I find any of their names or descriptions? Further digging will have to be done, I suppose. Or perhaps one of Alaska’s expert birders can provide some answers. I’ll add it to my City Wilds to-do list.

But back to oscines. Or songbirds, if you prefer.

Despite the enormous variety of songbirds found around the world, all apparently have one thing in common, Wetzel informs us: They have “precise control of a highly specialized vocal organ called a syrinx.”

According to the famous birding expert Kenn Kaufman (quoted by Wetzel), what sets oscines apart is not the syrinx itself, but “a whole series of really complex muscles attached to the syrinx (which) gives them much greater control” of the sounds they produce.

Got that?

“When a bird exhales,” Wetzel continues, “it can engage muscles inside the syrinx that control a series of membranes. As air flows over these membranes they vibrate to create a specific tune. Because songbirds have the most control over the their vocal organ, they can produce the most dramatic ballads.”

Here’s something else that sets songbirds apart, something that seems pretty darn cool: “While other perching birds produce their songs from instinct alone, songbirds learn theirs” from “adult tutors,” including their parents and other adults of their kind.

Exactly how ornithologists discovered this is no doubt a story in itself.

Wetzel points out that there’s no authoritative definition of what separates a bird’s song from its calls and “other noises,” but most experts agree that birdsong has two key functions: 1) attract a mate; 2) defend one’s territory.

Now that I actually knew.

There’s much more to learn about songbirds and bird song, but this seems a good place to wrap up this column. For now I’ll end with a few takeaways: first, based on what I’ve learned, it appears that all songbirds are passerines, but not all passerines are songbirds; second, passerines are essentially perching birds, with an arrangement of their toes (and some special muscles) that allows them to perch even when sleeping; and third, a specially complex arrangement of the syrinx and the muscles around it are key to what makes songbirds the special creatures that they are.

Now try explaining that in simple terms to your sweetheart or kids or curious friends. I’m going to start practicing my explanation right after finishing this column—or sometime soon, I swear. Maybe I’ll practice my explanation with Jan; she’s patient and a good sport. And she, after all, is what got me started on this whole songbird-passerine thing in the first place.

Anchorage nature writer and wildlands/wildlife advocate Bill Sherwonit is a widely published essayist and the author of more than a dozen books, including “Living with Wildness: An Alaskan Odyssey” and “Animal Stories: Encounters with Alaska’s Wildlife.” Readers wishing to send comments or questions directly to Bill may do so at akgriz@hotmail.com