Songs of wild birds tell an ecological story to Glen Ellen soundscape ecologist Bernie Krause
The drought has officially broken, the signs are everywhere. Lush grass carpets the hillsides, oaks are leafing out, creeks and streams run high. But what about the native wildlife?
It's 5:34 a.m., an hour before dawn, and in the Mayacamas mountains above the Valley of the Moon it's still too dark to see the rocks on the trail. Jacketed against the chill, my three companions are talking quietly as we wait without lights for the sun to rise.
The reason we're standing in the dark 1,300 feet up in the mountains next to burbling Sonoma Creek is because we're with Bernie Krause, a globe-trotting Glen Ellen audio specialist who has a passion for capturing the secret sounds of animal life. We're hoping to hear something special: the dawn chorus, the waking cacophony of wild birds on a spring morning in Sugarloaf State Park after a wet season of much-needed rain.
Krause, a musician turned soundscape ecologist, has been setting up his precision microphone and digital equipment to record the birds on this spot since 1994.
Today, we're not sure what we'll hear. The past five years, as the drought tightened its grip, Krause's recordings have documented the once rich symphony of birds here growing weaker and dimmer, nearly fading away. Last week with a national TV news crew, Krause's sensitive microphone captured the distant rumble of high flying jetliners, but little else.
As the gray sky lightens, a single bird in a tree to our right rings out a pattern, then falls quiet. “We should be hearing many birds by now,” Krause says. We listen as distantly as we can for any sign of them. The shushing creek passes by, headed downstream. Dawn approaches in silence. Then, a clear bright song erupts, and is answered, across the creek, by a welcome reply.
Later, Krause's recorder replays a modest chorus singing from the coyote bush thicket downstream, where the microphone was sited. It's a tiny, cheerful display of interacting birds, but nothing like the rich tapestry of songbirds that was here before the drought.
The dawn chorus - a rousing flurry of calls and songs as songbirds greet first light - can be disturbing outside your window if you're trying to get a few extra minutes of sleep. But in nature, it's a good way to measure how the millions of birds living among us are managing in the modern world.
No one is exactly sure why birds perform the dawn chorus. People who study avian behavior think it has to do with the birds announcing their presence, claiming territory, and attracting mates in the quiet of dawn, before they leave their roosts to forage for food.
Which makes sense. If you're a bird, hidden from sight in a shrub or tree, the quickest way to contact, find, and be recognized by the other birds spread out around you is with sound. And birds have evolved an incredible array of vocalizations for just that purpose, as well as special gear for the task.
Unlike the human voice box, or larynx, songbirds have two sound making organs, joined in an upside-down Y shape, just above their lungs, called the syrinx. With fine control, they're able to manipulate both sides of the syrinx independently. This lets them sing two notes at once, even one with rising pitch while the other is falling, and at different speeds and frequencies. That's how they can produce such an incredible range of twits, squeals, ringing tones and soaring, complex songs.
To Krause, those sounds are part of a living soundscape, a biophony, and he's one of the first in the world to seriously study how the audible part of an ecology reveals the life in that environment. Rather than pointing a microphone at a single bird to record its song, he listens to the entire landscape, and how the sounds within it interact. He's recorded insect larvae in streams, anemones in tide pools, and birds around the world.
With the computer in his office, he creates spectral graphs on a screen, and teases out the different layers of sounds the various creatures make. Krause points to a crucial feature: the unique sound each creature makes occupies a space, a niche, that lets it be heard amongst all the others, and the general din.
He has a lot of subjects to work with here. In the latest count, Sonoma County had more resident birds than any of the surrounding nine counties, 179 different species, and nearly that many more wing through here on migrations north and south. A growing number of bird enthusiasts and naturalists now specialize in listening to them - birding-by-ear, as the practice is known.
That's possible because each of those individual bird species has its own unique song patterns, Daniel Edelstein explains. Edelstein, a Marin-based freelance professional birding guide and consulting avian biologist, has been leading birding outings for more than 30 years, and teaches “The Ecology of Birds' Songs and Identifying Them By Ear” at Merritt College in Oakland, leading students to prime spots around the Bay Area and Sonoma County.