How to Know the Birds: No. 62, The Peterson Revolution v. 2021

  • What: Acadian Flycatcher, Empidonax virescens
  • When: Saturday, July 10, 2021
  • Where: Frick Park, Pittsburgh, Allegheny County, Pennsylvania

My maternal grandfather died well before I was born, so all I got is stories. But stories can be powerful. Like this one: the story that my grandfather’s life would have been vastly different had he grown up with a Peterson field guide. Call it an anti-story: the story of the person my grandfather might have been.

In any event, my grandfather came on the scene too late. He was a full-on adult by 1934, the year Roger Tory Peterson’s Field Guide to the Birds was published. Now wait a minute, Gramps. What about the field guides of Ralph Hoffmann and Frank M. Chapman from the decade before Peterson? Or the one that got the whole thing going?—Florence A. Merriam’s Birds Through an Opera Glass, published in 1889 when its author was all of 25 years old; and still a year before the birth of my grandfather.

I’m increasingly persuaded that we’re quite wrong in our assessment of Peterson. In a sense, we’ve got it precisely backwards. Merriam started the revolution; Chapman and Hoffmann and others pushed it forward; and Peterson completed it. That’s no diss on Peterson! Consider this analogy from classical physics: Newton started the revolution; Faraday and Maxwell and others pushed it forward; Einstein completed it.

Peterson, in a notorious self-reflection, put it this way: “I consider myself to have been the bridge between the shotgun and the binoculars in bird watching. Before I came along, the primary way to observe birds was to shoot them and stuff them.” There’re three problems with that. First, I’m not convinced Peterson really said those words, although as Kenn Kaufman has wryly let on, it sounds like something Peterson would have said. Does anyone know? Second, What about Merriam? I mean, the very title of her magnum opus is a shotgun blast straight in the heart of, well, the “shotgun school.” Third, as is so often the case in these matters, Peterson comprehended more deeply than any of his predecessors. The revolution wasn’t really about knowledge of birds, Peterson realized. It was about knowledge itself.

Hold that thought.

From A Field Guide to the Birds, 3rd ed. (1947).

When you compare Peterson with, let’s say, Sibley, it gets silly real fast. Consider their respective treatments of the Acadian flycatcher, Empidonax virescens. The only morphological character for the species, in Peterson’s initial formulation, is that it is greener than other flycatchers in the genus. Sibley has primary projection, malar contrast, the width of the eye ring, the shape of the lower mandible, seasonal variation in plumage aspect, and a lot more. Why, you can actually identify an Acadian flycatcher with the information in Sibley.

Recall that I compared Peterson to Einstein. (And recall that you’re holding on to that thought about Petersonian epistemology.) I might also say that the first edition of Peterson was the Wright Flyer, and that today’s field guides are the Airbus A350. There’s simply no comparing them. Except for one overarching equivalence: They’re both airplanes. They’re fundamentally the same technology. If you want to get from New York to Sydney, you’re going to do it by air travel—not by teleportation or a tunnel through the Earth’s core or something like that.

But what if we did have the equivalent of teleportation or a worm hole for the field identification of birds?

Earlier this month, I was in Frick Park, in the East End of Pittsburgh, where I grew up. Frick Park was my “patch” when I was a teen birder in the 1980s, even though nobody spoke of patches in that era. A great deal has changed in the 40 years since I first set foot on Frick Park: new signage, new trails, and a brand spanking new environmental center; there’s an entirely new wetland, replete with boardwalks, flood control contraptions, and more; there are mountain bikers everywhere and just generally more humans in the park than in the 1980s; and, perhaps most intriguingly, the bird community itself is rather different. The nesting hooded and Kentucky warblers are long gone, but there are red-bellied and even pileated woodpeckers there now.

One thing that hasn’t changed much, though, is the prospect for finding Acadian flycatchers in a part of the park called Falls Ravine. You can walk down Falls Ravine in the summer of 2021 and experience birding much as it was in the summer of 1981. Especially if you close your eyes. So that you don’t see the deer-denuded forest floor, the slick new guard rail, and the endless procession of mountain bikes. Anyhow, close your eyes. Sooner or later, you will hear it. Just as you would have 40 years ago. This sound:

Falls Ravine–Frick Park, Pittsburgh, Pennsylvania; July 10, 2021. Audio by © Ted Floyd.

It’s an Acadian flycatcher, but how do you know that? I learned that odd little song from regional birding experts Dave Freeland and Joyce Hoffman. Dave transmitted to me the key knowledge that virescens is the only deep woods “empid” to be heard in the Pittsburgh area, and Joyce taught me a memorable mnemonic for that explosive utterance: pizza! In due course, I learned how to interpret spectrograms of the song of the species, and even how to make my own recordings and spectrograms. Here’s the spectrogram of the bird in Falls Ravine:

Falls Ravine–Frick Park, Pittsburgh, Pennsylvania; July 10, 2021. Sound spectrogram by © Ted Floyd.

If you think about it, we’re in a catch-22. Dave and Joyce taught me the song of the Acadian, and I learned yet more from personal study and even spectrograms. But how on Earth did I realize it was a flycatcher of any sort, let alone an empid, in the first place? The truth is, a great many birders never attain that level of awareness. There are the birds you get to know if you spend enough time in Frick Park: the wild turkeys who patrol the wide trails, the wood thrushes whose flute-like utterances fill the woods, and more.

But the Acadian flycatcher is a birder’s bird, the sort of species you could go a lifetime without ever knowing. Dave is long dead, I’ve lost track of Joyce, and, honestly, who among us makes spectrograms on the fly? So we reach for our field guides. Peterson says spit-chee! for E. virescens, Sibley renders it spit-a-KEET. Again, the catch-22. You can’t even see the bird, way up the hillside, hidden in the hickory–beech canopy. And if you could, why isn’t it a vireo or kinglet or any other mostly olive, generally obscure, forest-dwelling bird?

I ran my recording past Merlin, the bird ID app. Just to be nasty, I withheld the date and location. Alls Merlin had to go on was the audio—of a fairly distant bird, by the way, and over the din of creek noise. Merlin doesn’t exactly “listen,” the way our human brains do; instead, it analyzes the spectrogram, those squiggles and scratches and such. Merlin pondered the matter for a few milliseconds, and returned this result:

Output from Merlin® Bird ID.

Wow. No other output. Just Acadian flycatcher. I tried it with other recordings of other species I made in the park, with similarly impressive results. My ABA colleague Nate Swick tested Merlin earlier this month on the Gulf Coast of Florida, and he reports the same thing. Merlin even identified a white ibis for Nate.

If the young Roger Tory Peterson were a programmer for Merlin, he would eventually go on to say: “I consider myself to have been the bridge between the field guide and the bird ID app in bird watching. Before I came along, the primary way to observe birds was to match them to words and pictures in books.” By the way, I love how Peterson and Merriam were precisely the same age—both were 25—when their revolutionary media first launched.

I’ve been birding for so long, meanwhile, that I have relatively little need for field guides or bird ID apps—especially in places as familiar as Frick Park. But I wasn’t the only birder at the park that day. My daughter, age 16, was with me. She’s a Coloradan, not a Pennsylvanian, and that Acadian flycatcher was her lifer. True, I was there. And I handed down to my daughter the wisdom imparted to me long ago by Dave Freeland and Joyce Hoffman. Next step: I would have flipped through my Peterson for backup, back in the day; my daughter tapped a few commands into the eBird/Merlin app.

In another part of the park, we came upon this sign:

Smartphone photo by © Ted Floyd.

“First, register for an account on” I think most readers know it, but eBird and Merlin are essentially the same deal, the two sides of a coin: Merlin tells you how to ID what you’re putting on eBird. Consider what the sign doesn’t say: “First, buy a field guide” or “First, take an ornithology course” or even “First, look through your binocs.”

We saw more than birds at Frick Park. Duh. But check this out. We were able to identify those non-avian entities. All of them. Not just the “classic” taxa like trees and chipmunks. For example, slime molds:

Some slime molds in Frick Park–Photos by © Hannah Floyd. Clockwise from upper left: dog vomit slime mold, Fuligo septica; honeycomb coral slime mold, Ceratiomyxa fruticulosa; red raspberry slime mold, Tubifera ferruginosa; wolf’s milk slime mold, Lycogala epidendrum.

Strangely, I was quite knowledgeable about slime molds by my late teens. The guy who taught me freshman biology in college, John Tyler Bonner, was the Sultan of Slime, at the time the world’s expert on these amazing aggregates of amoebae. I soaked it all up. Eusocial amoebae—who knew!

At the same time, my knowledge of slime molds was abstract. Perhaps I would study them in the lab one day. Or maybe, just maybe, encounter one in the field. But the idea of identifying them in the woods, the same way one might ID an Acadian flycatcher? That would have been absurd.

My daughter identified all those slime molds, along with other species, with the Seek app by iNaturalist (“iNat,” for short). She simply pointed her phone at the slime mold. That’s all. I suspect she and I probably did the first slime mold Big Day ever.

Folks, this is a revolution. When I was 16, the age my daughter is now, I must have passed by slime molds every time I walked through Fern Hollow or anywhere else in the park. But I wouldn’t have known it. And even if had I recognized those orange and red and black and dog-vomit yellow masses as slime molds, I wouldn’t have had any clue how to identify them. They might as well have been an unseen little bird in the woods saying spit-chee! or spit-a-KEET.

Like my grandfather, I came of age well after the revolution. When iNat launched in late 2011, I was the same age as my grandfather when Peterson’s Field Guide was published. And just as with the Field Guide, iNat had important antecedents: eBird in 2002, the Nikon COOLPIX in 1998, and, oh yes, BirdChat way back in 1991. All of those, even BirdChat, postdate my childhood.

But there’s a difference between the two revolutions. Peterson would go on to observe, problematically but I think accurately, that birding in the mid-20th century was something you got into if you were a teenager, and, in particular, an adolescent male. Of course there were—there always have been—the exceptions to the rule, the great birders who got into it via alternative demographic trajectories. But you had a leg up—you had privilege—if you were a young man.

No more. The propellor heads at iNat and eBird—yes, I know some of them personally—have no use for gatekeeping and passing torches. They just want people, lots of people, all sorts of people, to get fired up about identifying dog vomit slime molds, Acadian flycatchers, and, as my old friend Jack Solomon puts it, “everything else containing protoplasm.”

On that note, here’s a pic of Hannah, 16, and Jack, at the time a couple weeks shy of 80, iNatting Tubifera ferruginosa, the red raspberry slime mold, in Frick Park:

Smartphone photo by © Ted Floyd.

Vive la révolution!



Ted Floyd is the longtime Editor of Birding magazine, and he is broadly involved in other programs and initiatives with the ABA. Ted has written 200+ magazine articles and 5 books, including How to Know the Birds (National Geographic, 2019). He is a frequent speaker at birding festivals and has served on several nonprofit boards. Join Ted here for his semimonthly spot, “How to Know the Birds,” celebrating common birds and the uncommonly interesting things they do.