Identifying Migratory Birds by Sound in Britain and Europe, by Stanislas Wroza
Bloomsbury Publishing, 2024
256 pages, paperback
It may be apocryphal, but birds and birding are purportedly popular for three reasons: their omnipresence in a world where nature is increasingly absent from the quotidian, their otherworldly dinosaurian plumage, and the envy and awe inspired by their flight. There are of course more reasons; 10,000 or so is a possible number of species to count in a lifetime: fewer in number than beetles and easier to identify than moths. But it’s also fair to say that a lot of birds look alike: little brown jobs, as we fondly call them. Some of them are possibly recognizable only to each other. Which is where song and sound make their entrance, and over the decades, have garnered more and more appreciation and interest among the birding and ornithological community. The dawn chorus was once the ambit of renaissance poets—now it is something analyzed by artificial intelligence.
Moreover, the recent and rapid democratization of audio recorders, coupled with backyard lockdowns of the COVID pandemic, piqued an explosion of interest in the auditory element of what has traditionally been a visual-centric hobby performed by a visual-centric bipedal mammal. And this book is very much a product of that zeitgeist.
So what about that title, Identifying Migratory Birds by Sound in Britain and Europe? While the U.K. is part of Europe, birders from the continent may find this book less helpful, as it concentrates heavily on species vagrancy and migratory patterns across the U.K. Still, it illuminates the visual representation of bird vocalizations that birders the world over are increasingly fluent in, and it includes visual ID notes about jizz for difficult-to-separate (or presumably hard-to-hear) species.
Having used Nathan Pieplow’s more dedicated ear-birding books in the U.S., I initially thought Wroza had tried to do too much by marrying the aural with the visual, sonograms with flight shots. Is it information overload? No. In practice, it works well, providing both a tool for “nocmiggers” (those who record nocturnal bird migration) to peruse after a night’s recording, and for field-birders eking out the essential details of silhouetted flyovers in the mist of dawn, where the book’s combination of “seeing the sound” and insights into the flight style and morphology is an invaluable and unique dual-approach. And while the notes on flight style and morphologic impression are brief, they are well considered and accurate, especially at a family or generic level.
As an avid audio recorder myself, I remember moving from the Western to Eastern Hemisphere seven years ago and learning the songs and calls of an entirely new avifauna. In particular, an avifauna where the plumage was drab, but the songs were brilliant, complex, and typically unstereotyped. How many European warbler genera would you like on your new patch? All of them, please—in every shade of brown, but singing with the force of a symphony orchestra. I had two advantages: living in the middle of a national park with no anthropogenic sound pollution and free time—which had me doing nothing more for several years than standing in the woods with a pair of headphones, a lot of tangled microphone cables, and electrical tape to attach them to trees as I listened with my eyes closed. It was therapeutic and educational in equal measure, despite my physical therapist worrying I was going to fall over a log. The world had shrunk to a few hectares of ever-changing dawn soundscapes. The Japanese have 72 “seasons” (called kō) in the year, and listening to birds instead of just watching them exploded my birding year from four to 72 seasons, too.
But I digress; back to the book. Wroza works in the French Office for Biodiversity, and this book is an extension and improvement on his first one, La Migration Nocturne Par Le Son [Nocturnal Migration by Sound], apparently inspired by a trip to the U.S. where he no doubt saw that the U.S. was ahead of Europe in the adoption of sound recording, and particularly NFC (night flight call) monitoring. The original book wasn’t widely used outside France, presumably due to the language barrier and the fact it sampled hundreds fewer species than this new book.
The new book is an innovative mix. Most of the Xeno Canto QR codes printed next to each species’ sonogram and vocal description link to Wroza's own vast library of recordings, which provides consistency in the recording style, playback volume, and more. Many birders can surely empathize with the experience of scrolling through different recordings on headphones and suddenly being blessed by unexpectedly high volume (and the post-rock-concert-deafness that ensues). Most of Wroza's recordings are well chosen, although some are lacking in representing the true diversity of a species’s repertoire of vocalizations, which is slightly strange, given this is one area where the author wasn't restricted by an editorial word-count, book weight, or size.
This lack of variety, especially as it sometimes applies to unexpected species, is my primary criticism. One very commonly heard diurnal and nocturnal flyover in the U.K. is Redwing. It’s a winter visitor and awaited with impatience after the departure of breeding birds. Most people think of its call as stereotyped with little variation in pitch, modulation, and length. However, living in a place where Redwings overwinter by the hundreds, I spend a lot of time listening to and recording them. Some of their “aberrant” flight calls approach those of other Turdus species. After a while, I noticed the calls can change depending on the conditions, such as flying through heavy montane fog at dawn or dropping en masse to look for roost sites in the evening—among other behavioral and phenological factors. The behavior underlying these phenotypic sonic shifts is likely unresearched, so not doing it justice seems like a strange omission. Corvids can also cause confusion. Wroza has sampled five different but typical Common Raven croaks with slight variations in pitch and tonal clarity, but none of the links include less common flight calls, such as the hollow yet strangely musical “pop” or the descending semi-tones of fluty piping notes, which catch even experienced birders off-guard.
The greatest strength of the book is the precision of the illustrations and annotations of the sonograms. A little like the quirky artwork annotations of Lars Svensson, Dan Zetterström, and Killian Mullarney’s Collins Bird Guide: The Most Complete Guide to the Birds of Britain and Europe, Wroza's actual sonograms contain their own annotations, pointing out subtle differences in their visual jizz; these are sonic brushstrokes on canvas.
Sonogram of Pied Flycatcher, p. 139
These sonograms, or spectrograms if you prefer, are of course a wonderfully universal language. Who remembers the difference between pianissimo and mezzo piano, or interprets “vaihd vaihd vaihd, chaihr, chaihr” the same way? (That was a description of a Greater Whitethroat, vocalization, if you were wondering.) Or how about “it sounds sometimes thrush-like, sometimes harsher, not forming a melody, but shuttling up and down, sounding like a rippling brook”? It’s not the most objective or intuitive way of describing the notoriously complex warbling of Garden Warbler, an uncommon bird in many places and one that confuses many birders. It sounds fast and frantic yet also similar to other Sylvia warblers, even down to its alarm and flight calls.
So, Wroza’s dedicated attention to this non-arbitrary alphabet of sounds is instantly helpful, and, if you have a functional internet connection, the QR code link to Xeno Canto lets the reader instantly see differences in tone, pitch, modulation, and sonic quality. Suddenly, a “fluting” note and a “buzzy” note sound and look different. The black-and-white graphs are well printed and easy to read, and the prologue gives a useful primer (or reminder) on how to read them and translate them into an expected sound. For those learning to ear-bird, visiting unfamiliar biomes, or straining to recall migrant chips they might not have heard for nine months, this instant feedback loop creates a big neurological leap for the 95 percent of humans who are visually dominant creatures.
The neurology behind auditory learning, memory, and recognition is still spearheading many parts of the birding experience—partially helped by technology such as Merlin and partially by natural human curiosity. Audiomoth recorders are sold out as fast as they're produced, and home-made parabolas have become fairly commonplace and recognizable, as if we've all become avian astronomers listening to the biophony of breeding and migration. Scoping the local reservoir, or the daily walk on the local patch, has now been joined by a ritual eavesdropping on the skies. I for one find it very hard to switch my ears off, whether I'm cycling to work or sitting at a family barbecue.
Wroza's field guide is an invaluable resource for U.K. birders. It is accessible, yet expert. It should help when scanning through Audacity (sound editing software) the morning after a night of migration or out in the field at dawn trying to read the silhouetted shapes of thrushes and finches passing over in the gloaming dawn. The more this book helps people to balance their visual skills with the retention, recognition, and appreciation of the world of avian sound, the better their birding experience will be. Well, at least in the U.K. Hopefully, Wroza will now harness this success and create a wider biogeographical franchise.
Dominic García-Hall owned and operated a birding tour company in Argentina back in the day when there were very few. He sold it to go sit in an office all day in New York City but has since course corrected and now devotes most of his time to field recording, birding war zones, and forever editing a dawn chorus sound installation.
