Category Archives: Bioacoustic revelry

Wood crackle

The forest is full of strange and expected voices these days…

Here’s one, from a week or so ago. It was a dry day, following two months of record-breaking dry days. The sun was barely down. From the edge of a suburban woodlot, ear-sparkles came from the treetops, like the fizz and pop of a small pine-wood fire or the crackle of water droplets in hot bacon grease.

 

We walked into the woods with flashlights to find the source of the sound. An intermittent rain of velvety seed pods greeted us, the popped remnants of wisteria fruits. In the dry air they were all dehiscing at once, flicking seeds away from the mother plant in tiny explosive releases.

These are large vines, reaching all the way to the forest canopy. They’ve topped some trees, smothering them. Their vines muscle and squeeze. The seeds are loaded with toxins, so next year will see more colonists tendril-climbing the forest scaffold.

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Light, sound, hummingbird wings

From the dawn-light series (see also silk and moth wings)…

There is a moment in the early morning when the sun catpaws through the forest’s tangled blankets, illuminating my hummingbird feeder. The touch is gentle. The claws of midday are withheld. For two or three minutes, sun fires the blur of wings. For the rest of the day, the lights are off and wings move in gray-green, almost invisible.

hummer0hummer1hummer4Unlike other birds that power their flight with only the downstroke of the wing, hummingbirds flip their wings after the downstroke and generate more lift as they pull back their arms. The feather tips therefore scribe a figure-of-eight as the bird crams more gravity-fight into each back-and-forth. They do this fifty or more times every second. Humans can perceive only ten “images” per second and most movies are shot at twenty-four frames per second. To get an acoustic sense of the birds’ frenzy, I slowed a sound recording of the hummingbird in the photograph by one hundred times. The heart-beat thuds are the slowed wings, the strange wind is the sound of insects singing in techno-molasses:

(email subscribers, click on the header link to get to the sound file)

 

Fireworks echo through cellulose and chitin

I recorded the Sewanee annual firework display at a lookout spot across a mountain cove from the detonations. Before the pyrotechnics, the katydids made my ears ring, but the explosions out-shouted even the combined acoustic power of tens of thousands of singing insects.

Here is the finale of the show:


(email subscribers, here is a link to the sound, or click on the page title to go to the site)

If you listen with earphones, you’ll hear the low-frequency roar of the fireworks rushing down through the mountain cove for five long seconds after the blast. From where I sat at the Proctor’s Hall rock, the echo ran from right to left, flowing down, like a dark bird launching from the cliffs to the fields below the cove.

Thank you to the Sewanee Volunteer Fire Department for their annual extravaganza of sound and light.

 

High water: Buggytop cave.

Last week brought seemingly never-ending rainstorms to Sewanee. The downstream effects were dramatic. Crow Creek, running from the entrance to Buggytop Cave, south of Sewanee, was overtopping huge boulders and engulfing trees.

2015-07-05 buggytop boulder2015-07-05 buggytop treeThe water here comes from the sinkhole in Lost Cove and from the many streams that run from the south side of Sewanee. The water’s brown tinge is a melange of woodland tannins, soil erosion, and whatever washes from the streets and houses of exurbia.

Inside the cave entrance, the water’s sounds echoed from walls and the low ceiling. Quite a thunder.

(to hear sound, email subscribers need to click on the post’s title to link to the webpage)

The Buggytop cave entrance is a wide maw, easily walkable when the water is low. One hundred or more feet of limestone cliff extend above the entrance. The cave goes back about a mile into the limestone. According to Gerald Smith and Sean Suarez’s ever-fascinating Sewanee Places, the cave gets its name from the folded appearance of the collapsed rocks inside the entrance. Coincidentally, an abandoned buggy trail from Sherwood into Lost Cove passes not far from the cave entrance. Smith and Suarez also relate that the cave’s accessibility and popularity make it the number one site for local cave rescues. Many a poorly-equipped wanderer has become disoriented after their lights fail, both inside the cave and on the sinuous trail from the road. I was not tempted to join the list of rescuees by attempting a solo passage through the whomping water. Sitting in the presence of the echoing tumult was excitement enough.

2015-07-05 buggytop entrance

 

What does a rattlesnake sound like?

This:

…before being released from the bucket in which I transported the snake from a friend’s house.

One cannot age a rattlesnake by simply counting the rattles (they gain a rattle with each molt, but usually molt more than once per year). However, this one was a youngster, maybe two years old? My post from June 2013 has a look at their teeth and some better scale shots of a larger individual.

2015-07-07 rattlesnake 0112015-07-07 rattlesnake 0082015-07-07 rattlesnake 007May your crawlway be strewn with sunflecks and chipmunks, young snake.

Peepers: freeze protection strategies

When the temperature dropped below forty degrees, the frogs shut up. A few hours later, we hit the twenties, the pond was ice and the rocks from which the frogs had called were snow-covered.

The only sound was the creak of a Virginia pine’s knotty entrails, twisted by the weight of ice on its needles and branches. (Like other sounds on this blog, you’ll need to be on the website not the email summary, to hear.)

How do these crazy little frogs survive such temperature swings? Surely they’re all frozen to death by now?

A thermometer inserted just below the crust of snow and ice suggests the peepers’ first strategy. It is ten degrees warmer just an inch under the soil. By creeping into holes, bark crevices, and cracks in rocks the frogs find microclimates that, if not toasty, are more temperate.

2015-03-05 ice snow 010The peepers’ other defense is not so obvious. Their livers gush glucose into the blood, flooding their organs with sugary antifreeze. The bodies of these candied frogs can freeze without damage to their cells. Peepers can move in and out of this sugar-high within hours, making them well-adapted to the ill temper of the spring weather goddesses in eastern North America. After the last ice age, they were one of the first frog species to hop up north.

(For those wondering after my last post how a “spring pepper” might differ from a spring peeper, see here. Apologies for my many typos…)

Heck yeah: Peepers, peepers.

Rain + warmth = Pseudacris crucifer. The spring peeper.

Spring? Seriously? Appearing for one night only at a backyard pond in Tennessee. Tomorrow: the freeze returns.

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2015-03-04 peepers hawkins lane 007They are calling at an ear-ringing 85+ decibels. These frogs are so loud that birds have to adjust their songs near chorusing peepers. So crank this one to 11:

peeperspectroZoom in on the spectrogram (below) and we can see two call types: short upward sweeps and longer trilling sweeps. The short, untrilled sounds are the males calling to females; the zipped calls are aggressive signals to other males. Zip-a-dee-doo-dah. You can clearly hear each call type on the recording, minus Armstrong’s horn.

peeperspectro2Bonus: how many peppers can you spot in the photo below?

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