Tag Archives: bioacoustics

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)

 

Sounds from the edge of Boreas’ kingdom

A raven flies to its roost at dusk, wingbeats audible between the calls. Just before this flight, the bird was amusing itself with half a dozen others of its kind by harassing a sluggard-winged eagle. The ravens wove and swooped; the eagle flopped its great wings, finally passing out of sight on the horizon.

I think the squealing call at the end is a younger raven, greeting its homeward-bound parent.

Spectrogram of the same sound. Time moves left to right, pitch increases along the vertical.

Spectrogram. Time moves left to right, pitch increases along the vertical. “Stacked” lines are harmonics.

Night came and with it a frost.

Fir at nightI lingered and was rewarded by the sounds of Northern Saw-whet Owls. These tiny owls are common in dense forests of Canada and the Western US, especially forests with rotten trees to supply nesting holes. In the winter, some birds move south, so Saw-whets can be found all the way to Florida in the right season. The bird gets its name from the supposed resemblance between its repeated whistled call and the action of whetting a saw. The analogy is stretched, unless your saw comes with a flute.

The owls were a distance away, so the following recording has some lower and higher sounds filtered out to make the call come through more clearly.

SawWhetOwlSpectro