Sounds Wild and Broken, page 19
Animal thunder is one fruit of this productivity. To ears used to less fecund lands, the vigor of insects, frogs, and birds here is astonishing. In wetlands and temporary puddles, fed by the generous sky, thirty-one different species of frogs and toads sing in Georgia.
Each frog species has its preferred season and habitat, creating distinctive ensembles for every month of the year and location. At the edge of a forest of live oak, in a shrubby swale, I hear the signature of July in a coastal wetland, a diverse assemblage of tempo and tone: irregular, growly grunts from pig frogs, whining bleats from eastern narrowmouth toads, pulses of tinkling from cricket frogs, and enk enk honking from green tree frogs. The tree frogs crescendo until they obliterate all other sound, then snap into silence when they see me move. I wait, hunched against a barrage of probing mosquitoes, and the tree frogs ramp up again. As with the crickets on Mount Scopus, these frogs are usually nocturnal, but the warm day has drawn their chorus into the morning hours.
Last night, katydids throbbed as loud as a waterfall, their sounds dominated by the unified cha-cha-cha of the common katydid, spiced by the lisping rasps of the angle-winged katydids, and the swirling high clicks and trills of the aptly named virtuoso katydid. Now, as the sun reaches the tree canopy, cicadas erect a wall of a hissing, crackling sound. Unlike the katydids, cicadas are patchily distributed in the forest. As I walk, I find quieter pools of grassy forests where the high trills and chirps of crickets replace the cicadas, a sound more soothing to human ears. The insects here have similar timbres and rhythms to those of Mount Scopus, although species diversity and abundance of individuals are higher in this lush American forest.
At the sulfurous, muddy junction of land and marsh water, boat-tailed grackles, birds whose plumage shimmers with purple-black iridescence, clamor from palms and oaks. Their sounds, which keep the flock united and convey news of predators and new food sources, are like electric buzzes overlain on a jangle of metal flywheels. Red-winged blackbirds, resting in the reedy water edges, puff out their crimson epaulets as they blast their territorial signal, conk-a-ree, a fist of a song accented by a sweet trill at the end. The elaborate combination of high jingles and guttural chatters of grackles and blackbirds is characteristic of the icterids, a family that comprises the American blackbirds, caciques, grackles, and cowbirds. The more than one hundred other species in this family make songs of great complexity, usually ornate juxtapositions of slides, whistles, and harsh cries.
From the low spreading branch of a live oak tree, its nest perhaps hidden in drooping veils of Spanish moss, a northern parula works its buzzy song up the frequency scale, then ends with a quick downslur. The bird belongs to a sibling family of the icterids, the parulids, or American warblers. This is perhaps the least fitting of all bird family names. The more than one hundred species of parulids give tight, energetic lisps and buzzes, often arranged in short, repeated phrases, but do not warble. More than thirty parulid species nest, winter, or pass through this island on migration. Their changing sounds are one of the primary acoustic markers here of the passing seasons: territorial songs in spring, followed by the gentle chip notes as they feed in migration.
A brown thrasher perched atop a young pine delivers a boisterous stream of inventions and mimicked snippets of the local soundscape, showing off to rivals and potential mates alike. Like its close kin, the mockingbird, the thrasher is a listener and an innovator, assembling a rapidly delivered collage. The taxonomic name for these birds, mimids, belies the sophistication of their craft—they do not mimic but instead sample, remix, and add novelties, a process more creative than simple repetition. A boisterous wheep from near an old woodpecker hole in a longleaf pine tree comes from a great-crested flycatcher, joined by the sneezy pit-ZA! of an Acadian flycatcher sitting in the low branches of the pine, both members of the tyrannid flycatcher family. Their simple, emphatic songs are characteristic of this diverse American bird family.
From a neighboring oak tree, an American robin warbles his singsong phrases, groups of four or five whistled notes. Two fish crows wing overhead, cawing at each other. Barn swallows chitter as they arrow and twist in their pursuit of flying insects. These sounds signal where productive food patches are located. A Carolina wren, skulking in the saw palmetto that grows knee high, sings a rolling tea-keetle-tea-kettle, answered by a scolding call from its mate, tssk-tssk. Unlike many other songbirds here, the wrens duet, presumably to maintain the pair bond, and sing all year, a bright tumble of notes.
This acoustic melee is distinctive of the humid forests of eastern North America. Many of these sounds give us a northern taste of the American tropics. Especially in forests away from the poison clouds of airplane-sprayed agricultural fields and the herbicided quiet of industrial tree plantations, the loudness is like that of the South or Central American rain forests. No temperate forest can rival the outrageous number of species in the tropics, but the summertime exultation of sound is just as forceful. The timbres and rhythms here make up sounds also found in Eurasia—cicadas, toads, tree frogs, thrushes, and wrens—but also include, especially for birds, voices unique to the continent. The short, tight songs of American flycatchers and warblers are avian minimalists, their energies and meanings compressed into repeated exclamations and phrases. The icterids are like experimental electronic musicians, pushing bird sounds into modulations of whizzes, buzzes, and clangs, instantly recognizable to naturalists as an acoustic signature of the Americas. To human ears, these sounds combine the wild jumps among frequencies and timbres of electronic music—Milton Babbitt’s Composition for Synthesizer comes to mind, as do the repetitions and leaps of electronic dance music. The brown-headed cowbird, for example, sweeps up ten kilohertz in less than a second (about twice the range of a piano keyboard), a feat that takes the birds two years to learn. Other icterids, such as oropendolas, caciques, and grackles, make similar sweeps, mixed with harsh chatters or bell-like notes. Once mastered, the birds repeat these sounds tens of thousands of times over their lifetimes.
Crowdy Bay, New South Wales, Australia, is located 10,300 kilometers east of Mount Scopus and about the same distance west from Saint Catherines Island. The latitude is the same as that of Jerusalem and Saint Catherines but transposed to the south. I walk just after dawn through a mix of tall eucalypt forest and open heath, just inland from beaches on the Pacific Ocean. Although it is August, wintertime, I’m in shorts. The seasons here cycle between warm and hot. Rain, on average, falls year-round, with a peak in late summer, but droughts and deluges often interrupt this rhythm. The vegetation is evergreen, and most plants have leathery leaves, suited to summer heat, nutrient-poor soils, and unpredictable dry spells.
A family of four pied butcherbirds gathers in the limbs of a blackbutt eucalyptus. The contrast between their black hoods and wings and their white backs and bellies makes a strong visual mark against the tree’s dark green leaves. One bird looses three slow notes of extraordinary richness, flowing gold, lit from within by warm light. The bird repeats, downslurring the highest note, then adds another pure, steady tone at the end. A companion takes up the fluting, answering with higher notes, also languid and clear. The two then sing in call and response, and a third joins, overlapping the pair with its repeated five-note, undulating melody. They continue for several minutes, the calls serving to keep the birds in constant sonic contact and, presumably, to communicate danger, the location of foods, and ever-shifting social dynamics within the group. Then the fourth gives a harsh call, like a human blowing over a blade of thick grass clamped between thumbs, and the group wings into the adjacent heath, disappearing into the shrubbery.
The rich tones of the pied butcherbird’s song are gorgeous, and the song’s tempo is mellow enough for human ears to catch every note and inflection. There is an open-ended quality to the melody as the birds seem to pass it around and respond to one another with twists and elaborations of their themes. My brain’s aesthetic processes are aglow, maxed out by tonal quality, melodic creativity, and sound that speaks of a lively and intelligent web of relationships among the birds. For them, these sounds no doubt mediate their family lives and communicate to neighbors, as vocalizations do in other bird species worldwide. For my ears, the stunning sound is also a signature of this continent, its timbres and dynamics unlike anything I have experienced in the Americas, the Middle East, or Europe.
I walk on a sandy dirt road, away from the blackbutt eucalyptus and into the dense leathery-leafed Banksia shrubs of the heath. Here the sound of birds becomes less tonal but no less striking. A pair of little wattlebirds, colored like a chocolate cake decorated in streaks of white piping, creak like old hinges on a swinging gate. They intersperse goose-like honking amid these grating sounds, a raucous medley. A white-cheeked honeyeater flies into the shrub and the wattlebirds clatter their bills, perhaps as a threat. The honeyeater hops to an adjacent branch, at the crown of the shrub, and rips a series of tew tew sounds like blasts from a child’s toy laser gun. Black and gold wings flash as it leaves.
A noisy friarbird lances in from behind me and lands with a fluster of wings in the same shrub. Its red eye blazes from a bare-skinned black head. The bird seems more interested in thrusting its dagger of a beak through the foliage than singing, but it chatters as it works, a stream of sounds jumping from shrieks to harsh grunts to resonant ak sounds. Four yellow-tailed black cockatoos fly over. They giggle as they pump their wings, then whine wee-ar wee-ar. On the path in front of me, a dainty willie wagtail prances after insects, flicking its tail sideways, singing with urgent low-to-high repeats, like rubbing a finger on clean, wet glass. The bird throws rattles into this high squeaking, like a string of camera shutter snap sounds.
My experience at Crowdy Bay is typical of the shrublands and forests of temperate eastern Australia. Leave your windows open here and you wake to the ethereal caroling of Australian magpies, followed as the sun hits the trees by the scolding bickering of some of the dozens of species of honeyeaters. Lorikeets and parrots turn the air into a thicket of grating, thorny sound, loud enough to drown human conversation. Figbirds, gorging on fruiting trees in flocks of dozens, yelp at one another then burst into rich whistles. On higher ground, in temperate rain forests, whipbirds duet, one bird holding a single tone absolutely steady for two seconds then ending in an ear-splitting slash from high to low frequency, instantly answered by its mate’s sweet chew chew. Green catbirds sing with a strangled nasal waver, a sound like a mightily distressed cat or human baby.
Singing perhaps the world’s most complex and richly timbred birdsong, the lyrebird both mimics other species and adds its own flutes, whistles, crackles, and trills, a performance that lasts sometimes for hours, delivered so loud that the voice carries for up to three kilometers. Olivier Messiaen, the French composer who spent decades listening and responding to the music in birdsong, wrote that the nouveauté, novelty or strangeness, of the lyrebirds’ rhythms and timbre was absolument stupéfiante, absolutely astounding. Nothing he’d heard in Europe prepared him for this. The lyrebirds’ sounds, along with honeyeaters’ and butcherbirds’, inspired passages in his last orchestral work, Éclairs sur l’au-delà, premiered by the New York Philharmonic in 1992, six months after the composer’s death. The lyrebirds’ song was striking enough to carry it, via France, to the stage of Lincoln Center.
In my walk at Crowdy Bay, I hear no frog sounds and only one species of crickets gently pulsing from deep under the shrubs. In summer, though, cicadas rival the loudest birds, joined by katydids and more crickets. From wetter parts of the forest, when rain gathers in depressions and ditches, eastern dwarf tree frogs and striped marsh frogs call. Compared with Mount Scopus and Saint Catherines Island, Crowdy Bay’s insects have similar timbres and rhythms, instantly recognizable as the chirping of crickets or the harsh whine of cicadas. The frogs here, too, pluck, fibrillate, and pop with sounds reminiscent of those on other continents, but without the ear-splitting vigor of American choruses.
The energy and textures of the soundscape here are dominated by birds. A few species—the silvereyes and superb fairy wrens—give soft warbles and gentle trills, but these flow into an otherwise clamorous, muscular stream. Butcherbirds, magpies, honeyeaters, and others produce a sonic confluence of virtuosic leaps through rich harmonies and jarring, atonal pulses and eruptions. Angels are playing woodwinds alongside performances of musique concrète and industrial found sounds. Absolument stupéfiante.
The vigor and tonal diversity of Australia’s birds struck many nineteenth-century colonists. Naturalist William Henry Harvey wrote in 1854 of “several chirpers, a few Whistlers, many screamers, Screechers, & yelpers, but no songsters.” To human ears used to European sounds, Australian birds are “exotic,” “disruptive,” or “ugly” according to surveys of recent émigrés by anthropologist Andrew Whitehouse. Some people are impelled to return to Europe, unable to bear the cacophony of birds that “crash into your consciousness.” These reactions are partly founded in our affinity for the sounds of our youth. Psychologist Eleanor Ratcliffe and her colleagues found that familiarity of timbre and melody are predictors of how restorative we find birdsong. Andrew Whitehouse’s surveys found that Australians living in the United Kingdom hanker for the sounds of their former home, sometimes playing recordings to awaken aural memories. The power of bird sounds to forcefully evoke in us feelings of alienation or belonging is partly a reflection of how divergent the sounds of different continents can be. These feelings are also reminders that the sounds of other species are lodged deep within us, carried within our subconscious as aural compasses, orienting us toward home.
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It is perhaps an absurd overgeneralization to characterize and compare the sounds of entire regions or continents. Summaries belie inner complexity. After all, every habitat has many sonic variations and textures. Walk a kilometer or two through any forest and your ears will encounter variegations of tone and rhythm from the combined voices of sometimes hundreds of species. Yet alongside this fine-grained local texture, the voices of Earth also differ on a continental scale.
Some of this sonic diversity emerges from the varied physicality of the world. Earth has many forms of wind, mountain, rain, wave, beach, and river. Raindrops are larger in the Amazon than in North American skies. Northerly coastlines retain the mark of scouring glaciers, and their rocky headlands have more assertive voices than the sands and muds of unglaciated subtropical shores. Rivers meandering through continental interiors are slurred and languid compared with water coursing down mountain slopes. The geologic history of the world has created varied surfaces and flows for unvarying physical laws to play against.
Evolution adds two more creative forces to this global diversity of sound. The happenstances of history have populated different regions with varied branches of the tree of life. Each branch has its own stories of origin, migration, species diversification, and extinction. Combined, these stories yield diverse geographies of sounds. Overlain on this, every species experiences its own path of aesthetic innovation and sonic adaptation to place. Because these evolutionary paths are guided by forces that are often fickle and improvisational, the sounds of each species diverge in unpredictable ways. Over millions of years, divergences scale up to give whole regions different sonic characteristics. These processes contrast with those that shape the sounds of water, stone, and wind: A raindrop of a given size makes the same sound whether it lands on rock in America, Israel, or Australia. The songs of animals in these places, even species of very similar sizes and ecologies, cannot be deduced from physical law. History and the quirks of animal communication add delicious layers of contingency and caprice to life’s voices.
On any place on Earth, we hear the voices of both indigenous and colonist animals. Some of this mix is recent—European starlings singing alongside American crows across much of North America, for example—but most stories of animal biogeography have deeper roots. When we look back tens or hundreds of millions of years, we find that the modern distribution of every group of animals results from some species cleaving to home and others striking out for new land. A few of each type then split into new species, producing a rich tangle of geography and taxonomy.
The oldest singing animals, the crickets and their now-extinct kin, evolved on the supercontinent Pangaea. It is not surprising, then, that the sounds of crickets today are so similar among continents. Each place inherited crickets from a singular landmass that then split. But crickets are hardy too, and can withstand ocean journeys on floating vegetation. Some of the unity we hear is the result of more recent dispersal. The familiar chirpers of fields, gardens, and parks—the gryllina “subtribe” of crickets—are found on every continent except Antarctica and have colonized many oceanic islands.
A similar pattern of ancient unity and more recent colonization accounts for the distribution of other singing insects. Katydids or bush crickets likely originated on the southern supercontinent Gondwana, one of the landmasses formed when Pangaea broke apart. They then repeatedly jumped among landmasses, producing a family tree with close cousins on different continents. The marbled bush cricket that I heard in Jerusalem belongs to a clan that invaded the temperate regions of Europe and then North America from Australia. The common katydid that pounds the night air on Saint Catherines Island belongs to a different branch of the family tree, one that colonized the Americas from Africa. Cicadas also have a global distribution, their present form dating back at least to the time when Pangaea broke up. Since then, they have repeatedly jumped among continents, with close kin on widely separated landmasses. The periodical cicadas of North America, for example, are taxonomic cousins to some Australian cicadas.
