American Birding Podcast



Heard Only

Arnold Small (1926–2000) is on anybody’s short list of birding greats from the latter half of the twentieth century in North America. I never met Small, but I’m certain I would have enjoyed his company. He was witty, opinionated, and fun. I’ve particularly enjoyed his many contributions to Birding magazine.


Arnold Small hated heard-only birds. They are incorporeal, according to Small, and not really there. They are disembodied voices, a far cry from the real deal of the real bird, right there, in the flesh, in Technicolor glory, in plain view, right in front of your eyes. Head-only birds don’t count for your life list, in Small’s view.


I love heard-only birds, and I’ve got a bunch of them on my life list.


My love of heard-only birds was affirmed during a trip last week to Portugal. For me, the highlight of the visit was a nocturnal birding outing, one of many fine offerings of the Sagres-based Festival Observação de Aves. Our destination for the evening was the Cabranosa hawkwatch, a mile or so north of Sagres.


The weather was beautiful—cool, crystal clear, and a bit breezy. And turnout was good. I counted 26 participants, and I suspect I missed a few. As twilight fell, we caught glimpses of several owls and nightjars. It got darker, and we watched the sky come alive—first Venus and Jupiter, then Arcturus and Vega, then all the rest.



Night birders
Nocturnal birders near Sagres, Algarve, Portugal; 1 October 2010. Photo by Jaap Schelvis–


We were enjoying the magical experience of nautical sunset, when it’s still light enough to see silhouette but too dark to make out color. Then I heard it. A rich, wavering whistle, drawn out, melancholy but powerful. “Stone-Curlew!” several of my companions proclaimed.


Click here to listen to a recording of the Stone-Curlew’s flight call.


I’d gotten my lifer Stone-Curlew (or Eurasian Thick-Knee, in ABA parlance) just a few days earlier. It was, if you will, a “seen-only” lifer, flying silently across a wetland. The next day I saw another, also seen-only, a dopey bird standing out in a plowed field. But this one was better, so much better. This one was the real deal; I’ll never forget that haunting cry in the semidarkness, the very essence of the gorse-and-oak shrublands of the coastal headlands of extreme southwestern Europe.

Twilight gave way to full-on darkness. The sky was magnificent. I’d never seen so many stars at sea level. The Milky Way was glorious, and Uranus was just barely visible to the naked eye.

Our leader, Ricardo Tomé, led us down a sandy path to a rather improbable structure about the size of a horse trailer. It was a mobile radar unit, and what we saw there was astonishing. We were watching individual birds migrating in real time across the monitor. I’m not talking about those Doppler radar images that give you a coarse reading on the overall magnitude of nocturnal migration. No, these were individual birds—perhaps Northern Wheatears and Willow Warblers—parading across the radar screen.



Radar out 

Ricardo Tomé shows us birds migrating by night over Sagres, Algarve, Portugal; 1 October 2010. Photo by Jaap Schelvis–

We couldn’t hear the birds, even though they were fairly close to the ground. Wheatears and Willow Warblers—if that’s what they were—are silent on nocturnal migration. So are most other nocturnal migrants in Europe. It didn’t matter. The experience was spellbinding. For me, it was just as dramatic—and every bit as “real”—to watch those blue dots on the radar screen as to see the birds through binoculars during the day.



Radar close 

Close-up of birds migrating by night over Sagres, Algarve, Portugal; 1 October 2010. The dotted blue lines show the real-time trajectories of migrants, perhaps Willow Warblers and Northern Wheatears. Photo by Jaap Schelvis–



When you think about it, everything we experience is just that: an experience, an impression, reality through the filter of our senses, brains, and hearts. A tiny amount of electromagnetic radiation excites the photoreceptors in our eyes, and our brains turn that signal into the experience of seeing a bird. Equivalently, a few air molecules jostle about in the vicinity of the cochleae of our ears, and our brains convert that small pressure differential into the experience of hearing a bird. With apologies to Arnold Small, the two experiences are on perfectly equal footing. Energy—in the form of a “signal”—is transmitted from a source (the bird) to a receiver (the birder), and we declare it to be real. Whether the signal is visual or auditory seems irrelevant to me. And it doesn’t bother me if we get a bit of a boost from technology—binoculars for Arnold Small, radar for yours truly.

Our last destination for the evening was a well-lit old fort just a stone’s throw from the Atlantic Ocean. Ricardo was hoping we might glimpse or hear a few migrants. We didn’t, but the night sky was overwhelming. As breathtaking as it is to see the night sky, the visual spectacle of the heavens is only the tip of the cosmic iceberg. The stars are seething cauldrons of gravity and invisible radiation, of gamma rays and relativistic jets, of incomprehensible heat and pressure.


 Imagine if there were nothing more to astronomy than the seen-only experience of the silent stars.