What We Know-And How We Know It


It’s an annual tradition. Each year on August 12, we wake up early, crazy early, and watch the Perseids. This year there are ten of us: my two kids and I; a preteen and her parents; a woman from Belgium, about my age; two “little old ladies,” as formidable as they come; and, in the name of diversity, a token “old white guy,” witty and worldly. We assemble quietly, yea, silently, under a linden tree at a residential street corner, then walk rapidly a short distance into the park.


I’ve entered that park close to ten thousand times, but there’s always a moment of wonder, that instant when the sterility of the suburbs yields to the awesomeness of nature. Especially at night. In the blink of an eye, the parked cars, cookie cutter homes, and obnoxious streetlamps are gone. Up ahead: trees and a lake, a meadow and a marsh, and the big sky, full of stars. There is no transition zone, no “ecotone” from the artificial to the natural. You simply turn the corner and, boom, you’re in the forest primeval. It’s the first night of Creation, and you’re the first human on Earth.




We go down the trail a bit farther, and get underway. Our eyes haven’t yet adjusted to the dark, but the meteors dazzle. Each year, the Perseids peak on the night of Aug. 11–12, with the best viewing between midnight and dawn on Aug. 12. It’s 3:30 am on Aug. 12-check. Needless to say, you don’t want clouds and haze. The night is clear and cool-check. And of course you don’t want any moonlight. Moonset was two hours ago-check. We haven’t even gone around the circle introducing ourselves, and we’ve already seen a half dozen meteors. My kids know this song, “Tonight’s gonna be a good night.” Indeed.


We see the galaxy in Andromeda and the planet Uranus; we see bats and a heron and even two hawks roosting in a tree. We smell a skunk. We hear an owl, and some geese, and a symphony of crickets. And when the temperature drops below the dew point, we suddenly feel cold and wet.


It’s funny: All this happened just a couple nights ago, but it might as well have been a scene from my childhood in the late 1970s. I knew about the Perseids back then; I knew bats and crickets and the pleasing scent of a skunk; and I knew that dew forms overnight. The one thing I didn’t know was birds.




We settle down, and listen for nocturnal migrants. Almost immediately, a Chipping Sparrow flies over. Then another. Then a Lark Sparrow. Then more Chipping Sparrows. During the course of about 25 minutes, we hear some 20 sparrows. The flight call of the Chipping Sparrow is fine and piercing; the Lark Sparrow’s is flat and muffled.


How do we know those differences, Chipping vs. Lark?


This is a spectrogram of the flight call of a Chipping Sparrow. Recording by Terry Davis–xeno-canto.org.


I learned the differences by studying Flight Calls of Migratory Birds, a CD-ROM put out more than a decade ago by Bill Evans and Michael O’Brien. A CD-ROM, eh? The preteens in our little group would tell you that that technology is as antiquated as an eight-track player. As to the rest of the folks in our group, they learned the flight calls by way of some audio files I emailed them prior to the outing. Email, eh? Email, the kids assure me, is about to go the way of CD-ROMs, eight-track players, and the dinosaurs.


Now think back to ca. 1980, when I was the same age as the three preteens in our gathering of somnambulant natural historians. We didn’t have email back then, we didn’t have CD-ROMs, we didn’t even have nocturnal flight calls. What I mean about flight calls is: We had no information, no knowledge, no awareness. A little chip note in the night sky could have been anything-a sparrow, a warbler, a cricket, or a bat. Most likely, it was none of the above. It was just a sound without a name, as easily overlooked and quickly forgotten as a rustling in the leaves.




A fight breaks out! One of the “little old ladies” (LOLs, LOL-get it?) has whipped out an app for naming the stars, but the other LOL tells her to turn it off. The latter LOL wants a screen-free experience. Okay, I’m embellishing. We’re all friends out there. It’s a totally good-natured tussle. But it gets me to thinking about something.


I can rattle off the names of the stars. I can find various Messier (“deep sky”) objects. I know where to find Uranus, a dim blue dot even through good binoculars. I don’t need no stinkin’ app.

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Go online and navigate the night sky-from any location on earth, day and night, past, present, and future. Image from neave.com/planetarium.


True, I don’t have an app with me. But it would be dishonest to say I haven’t been aided by technology. Before we headed out, I went online and confirmed the location of Uranus: Find Hamal and Sheratan in the constellation Ares, then trace a line over to dim Kullat Nunu in Pisces, then drop down to even dimmer Torcularis Septentrionalis, right next to Uranus.


I said I knew Uranus as a kid. I should say that I knew of its existence. I’d never actually laid eyes on the planet. I didn’t have online sky charts with minute-by-minute animations for any location on Earth. I didn’t have binoculars, necessary for seeing Uranus anywhere with light pollution. And I didn’t have a 50 milliwatt laser, essential for showing folks where to look for the planet.


Both LOLs were right. I completely get the need, the very real need, for app-free and otherwise screen-free apprehension of the natural world-especially that purest expression of nature, the sky at night. But I also get the need, the very real need, to understand how it all works: with apps and animated sky charts, with binoculars and laser pointers, and more.




The night wears on. The Canada Geese have quieted down. The pulse of migrating sparrows has passed. I close my eyes and hear nothing but crickets. “Nothing but crickets.” What a ridiculous thing to say. You might as well say, “I went to McGee Marsh and saw nothing but warblers.” Crickets are musical, challenging, and fantastically diverse. They have the allure for me now that warblers did when I was a kid. Tonight we learn the easy ones: snowy tree cricket, Allard’s ground cricket, fall field cricket. Other tree crickets and ground crickets aren’t as straightforward, and a katydid is unfamiliar to me. I’ll have to make a recording and look it up online.


Check out what I just said: I’ll record that katydid and go online. With inexpensive recording gear and a visit to Singing Insects of North America, you can put a name on pretty much any cricket in America. Again, go back to 1980. If you were a natural historian at that time, chances are, crickets were just, well, crickets, as nameless as the flight calls of sparrows migrating in the dark.

The song of the snowy tree cricket is loud, low, and distinctive. Recording by Wil Hershberger–songsofinsects.com.

The song of the snowy tree cricket is loud, low, and distinctive. Recording by Wil Hershberger–songsofinsects.com.


Perhaps the easiest cricket of all is the snowy tree cricket, the “thermometer cricket” studied by Amos Dolbear in the late 19th century. This cricket’s song is gratifyingly low-pitched (I’ll be able to hear it long after Allard’s ground crickets and even Chipping Sparrow flight calls are inaudible to my aging ears), musical, and evocative. Anyhow, Dolbear noticed the precise relationship between air temperature and chirp rate, a mathematical formula known as Dolbear’s Law.


That’s all well and good, but there’s just one thing. Dolbear didn’t know what species he was listening to. I’m not dissing Dolbear. I’m just saying, He lived before the Digital Age.



We humans can't hear big brown bats, but we know what they sound like. Recording by Scott Altenbach–Bat Conservation International.

We humans can’t hear big brown bats, but we know what they sound like. Recording by Scott Altenbach–Bat Conservation International.


We’re well into the period known as “nautical dawn.” According to an online resource, nautical dawn stretches from 5:04–5:40 am. The big brown bats are putting on a marvelous show, with many of them flying right in front of us. One actually bisects the group. I can’t hear them of course. Neither can the kids. But I know they’re calling. I understand what they’re doing, and I know how echolocation works. Yet we didn’t always know about echolocation. The discovery of echolocation wasn’t all that long ago. Donald Griffin discovered it in the 1930s. I’m old enough that I studied with Griffin in the late 1980s.


Griffin was well into his 70s at the time, and I confess that I wondered whether he was frankly off his rocker for speculating that avian cognition is far more sophisticated than we ever knew. What can I say?-Griffin’s instincts were subsequently proven to be spectacularly correct. Every week, it seems, some scientific study reveals some amazing new ability of the avian mind.




At 5:39 am, during the final seconds of nautical dawn, the temperature hits the dew point. I should have known it was coming: The snowy tree crickets are singing so slowly. The crickets don’t lie, but I can’t help myself: I confirm it online. An instant later, “civil dawn” (5:40 am–6:09 am) is upon us, and a Mourning Dove sings. We can see it, actually, a silhouette in a gnarled willow.

A fuzzy patch in the night sky, the galaxy in Andromeda is home to about 1,000,000,000,000 stars. Image from nasa.gov.

A fuzzy patch in the night sky, the galaxy in Andromeda is home to about 1,000,000,000,000 stars. Image from nasa.gov.


Only the brightest stars are visible now. A final Perseid blazes across the zenith, near the position of the galaxy in Andromeda. The galaxy is invisible now, but we know it’s there. Way out there. The galaxy in Andromeda is more than 2.5 million light years away. I’ve known that all my life, in the same way that I’ve always known about bat echolocation. But our knowledge of the galaxy’s whereabouts, like the discovery of echolocation, is relatively recent. It wasn’t until well into the 20th century-around the time Donald Griffin was doing bat research-that it was firmly established that the galaxy in Andromeda lies somewhere far beyond the local galaxy.




A cranky Spotted Towhee calls, and a Song Sparrow sings weakly. The crickets are silent; the bats are gone; and the brightest stars are extinguished. It’s still 10–15 minutes till sunrise, but we’re done. We’re back in the realm of daylight, the realm of the familiar. A migrating Chipping Sparrow is coming in for a landing; we hear it first, and then we actually see it land in a cottonwood.


The midsummer nocturnal migration of Chipping Sparrows is a recently discovered phenomenon. We didn’t know until a decade ago that the interior subspecies, arizonae, undertakes sustained night flights from breeding grounds in the mountains to molting grounds in the central and southern Great Plains. These flights are chiefly nocturnal, and they take place in July and August.


Although our understanding of the phenomenon is recent, our awareness of it is older. Edwin Way Teale, in his mesmerizing Journey Into Summer (1960), seems to have known about it. He writes of hearing the flight calls of sparrows in Colorado in late summer. Teale conjectures that he’s hearing White-crowned Sparrows, flying from their montane breeding territories to their lowland wintering grounds. The second part of his formula is unquestionably wrong: White-crowned Sparrows in Colorado aren’t altitudinal migrants. The first part seems off too: White-crowned Sparrows in Colorado, unlike Chipping Sparrows, probably aren’t on the move until autumn. I think Teale was hearing Chipping Sparrows. He just didn’t know. Teale, like Amos Dolbear, lived before the Digital Age.




My kids often ask what it was like back in the day. To them, the late 20th century might as well have been the late 19th century-and, as to whether CE or BCE, what’s the difference, It was a long time ago. Those were the olden days, with CD-ROMs and fax machines, eight-track players and disco, latrines and horse-drawn carriages, print field guides and cave art. What’s changed the most for me, though, isn’t the technology per se. Rather, it’s what we’ve done to ourselves with technology.


We’re supposed to be beating ourselves up about how technology has undermined-more than undermined, totally ruined-our capacity to engage and appreciate the natural world. You’ve heard all the jeremiads against this modern age of ours: We’re too wired, we spend too much times on our screens, we’re too dependent on our devices, we just Google stuff instead of actually learning it.


But where would we be without our gadgets? I’ll tell you where I’d be, or, rather where I’d not be: I’d not be in nature, not nearly as much. Our delightful foray in the dark was organized online; our understanding of flight calls came from a CD-ROM; our knowledge of cricket songs is based in large part on an internet resource; our viewing of Uranus was made possible by an animated sky map; and so forth. Without technology, the galaxy in Andromeda would just be a nebula in the local galaxy, and the planet Uranus would just be another star; without technology, bats are blind, birds are dumb, and meteors are “falling stars.”


So go online. Download that app. Get wired. Do those things, and immerse yourself as never before in the wonders and glories of the natural world.


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