Field Recordings
The sounds of our land are just as important as the sights, and we are slowly building a library of field recordings from across our property.
Birds
The richest bird song is usually in the half hour before dawn. I set the field recorder up in the evening and record all night, so I can capture the dawn chorus without having to wake up at 4 AM. When the long winter starts to take its toll it is wonderfully restorative to have the sounds of spring and summer near at hand.
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Clubmoss City is a one-acre bit of boreal forest on the western edge of our land. Red spruce and balsam fir grow here above a lush understory of clubmoss and fern. This recording features a choir of coyotes joining in with the dawn chorus of golden-crowned kinglets, hermit thrushes, wood warblers, scarlet tanagers and more.
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These barred owls conversed much of the night. This track features three of the best bits spliced together.
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Along with all of the meadow and scrub birds in this recording—song sparrows, white-throated sparrows, chipping sparrows—you can hear our resident bluebird warbling at 3 seconds in. You can hear our phoebes too, which nest in the wood shed on the other side of the house, but prefer to hunt here in the orchard. The house wren bubbling away would soon evict the bluebirds from their nest box.
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The tree swallows twittering in the background occupy a nest box in the middle of the back field, the song sparrow nests behind a pallet in one of the nearby barn stalls, and the robin and mourning dove nest in the adjacent Sugar Garden. If you listen carefully you can hear a bittern calling from a nearby wetland. Most of the birds in this recording, though, are calling from the surrounding woods.
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The south slope canopy is mostly large white pines, with an understory of maple, hemlock, spruce, ash and birch. Hermit thrushes love it here, and there are at least four different males singing in this recording. As the dawn chorus builds the hermit thrushes are joined by winter wrens, black-throated blue warblers, common ravens, dark-eyed juncos, Blackburnian warblers, ovenbirds, yellow-bellied sapsuckers, brown creepers and more.
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Butternut Hill is covered with rich hardwood forest on its eastern flank and with dense hemlocks to its west. It has a particularly diverse dawn chorus, including some species—like eastern wood peewees (listen at around 21 minutes in)—found nowhere else on our land. In this recording at around the ten minutes mark a deer stumbles across the field recorder and is not happy about it, stamping and huffing for the next fifteen minutes.
Note the common nighthawk flying overhead at around two minutes in, and the nearby barred owl calling a minute later.
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There is a small wet meadow in the southeast corner of our land, surrounded by tall pines. The dawn chorus here is particularly atmospheric, featuring the kaleidoscopic song of a winter wren along with white-throated sparrows, common yellowthroats, Nashville warblers, and more.
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Sugarbeard is a large, craggy sugar maple on the northeast corner of our land. Here the songs of wood warblers and vireos mingle with the calls of our neighbors’ roosters. Taken near the end of the dawn chorus, this recording tapers into gentle morning bird song, with a raven low overhead.
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American woodcocks are wonderfully weird birds. Related to familiar beach-dwelling shorebirds like sandpipers and sanderlings, they live in damp forests where they use their long bill to probe around in the leaf litter. Male woodcocks display in early spring, performing in open fields next to dense woods. The one in this recording used the mowed orchard paths as his display ground. After a long series of nasal peent calls, the woodcock takes off into the air, and as he spirals around his wings produces a series of ghostly twittering sounds. Then with sudden silence, he flutters down to his chosen spot, and the performance begins anew. This woodcock is the first one I’ve heard performing on our land.
Bats
Every summer night bats flit through our forests and course our fields, searching for moths, mosquitoes, beetles and more. We sometimes watch them hunt at dusk, but their lives would otherwise be a mystery to us if not for field recordings.
Bats use echolocation to navigate and find prey in the dark. Most bat calls are too high for humans to hear, but with sensitive microphones we can record their calls and view them on spectograms, which plot the frequency of sound over time. Each bat species has a different shaped call, although overlap between species makes identification difficult.
In 2024 we used an automated recorder to survey our bats. We left the recorder out every night from May through September. By late summer we were recording mostly crickets, but we still ended up with 12,000+ recordings of bat calls. With the help of bat ID software, we identified seven different species: silver-haired bats, hoary bats, big brown bats, eastern red bats, northern long-eared bats, little brown bats, and tricolored bats. Four of these are discussed below.
Although bats are not as maligned as they once were, few people realize the importance of bats. Bats eat enormous numbers of bothersome and destructive insects such as mosquitoes, blackflies, spongy moths, corn borers and potato beetles. A single bat can eat over one thousand insects a night.
But beyond their economic and ecological importance, bats have a surprising amount in common with us. They are the longest-lived mammal for their size—some bats living over forty years. They have complicated social dynamics, forming long-lasting relationships that persist as they travel far and wide. Mother bats only have one or two pups a year, and tend to them carefully. Male bats sometimes shepherd juvenile bats around, perhaps helping them find places to roost and hibernate. Bats are under extreme duress from disease, wind turbines, insecticides and human disturbance, and their future is uncertain. I hope they will always be here to keep us company at night.
Silver-Haired Bat
The most frequently detected bat species on our land is the silver-haired bat (Lasionycteris noctivagans), which lives in forests across North America. The recording here is a typical hunting sequence, with the calls becoming more frequent as the bat approaches prey, then returning to normal as the bat continues on. By slowing down the sound eight times, the pitch is lowered three octaves and you can hear the action for yourself.
silver-haired bat hunting sequence spectogram
Hoary Bat
Near-nightly visitors to our orchard and back field, hoary bats (Lasiurus cinereus) live across North America and even into South America. They are champion flyers. An ancestral hoary bat made it to the Hawaiian Islands, where it evolved into Hawaii’s only endemic mammal, the Hawaiian hoary bat.
The largest bat in eastern North America, the hoary bat also has the lowest pitched call. If you have keen hearing you can sometimes hear hoary bat calls unaided—they sound like extremely high pitched clicks. In this recording the call sequence has been slowed down eight times, so you can hear the variations in pitch. Higher pitched calls provide more resolution, but lower calls travel greater distances, revealing more of the landscape.
hoary bat call sequence spectogram
Little Brown Bat
Little brown bats (Myotis lucifugus) are smaller than silver-haired or hoary bats, and their calls are proportionally higher pitched. They were likely once the most common bat species in Vermont, but in the last couple of decades little brown bat populations in the northeast have declined by over 90%. The species is now considered endangered by Canada, the IUCN, and the state of Vermont, although it is not yet federally listed. We have detected them on our land only a handful of times.
The cause of little brown bats’ decline is white nose syndrome, a deadly fungal disease that attacks the bats while they hibernate. White nose syndrome was likely spread to America from Europe by cavers. It threatens every species of group-hibernating bat in the United States, and has hit the genus Myotis particularly hard. There are signs that little brown bat populations are stabilizing, and hopefully we will have more little brown bat visitors in years to come.
little brown bat call sequence spectogram
Northern Long-Eared Bat
Northern long-eared bats (Myotis septentrionalis) use their enormous ears to detect insects not just in the air but crawling on vegetation. They can pluck a beetle right off a leaf. Their calls sweep down very quickly over a wide band of frequencies, and when slowed down this sweep adds a bit of zip to their calls.
Northern long-eared bats have been decimated by white nose syndrome. Populations in the northeast have declined by over 97%, and they are now a federally listed Endangered Species. It is a privilege to have them on our land.
northern long-eared bat call sequence spectogram