A form of flattery
It’s hours before dawn, but crystalline song brings me wide
awake. A nearby mockingbird is decorating the night with a rather
simple ditty.
I’m awake because I’m trying to decipher what it is this
particular member of the mimic thrush group is mimicking. I come up
empty.
A form of flattery
It’s hours before dawn, but crystalline song brings me wide awake. A nearby mockingbird is decorating the night with a rather simple ditty.
I’m awake because I’m trying to decipher what it is this particular member of the mimic thrush group is mimicking. I come up empty.
Sometimes the song is unmistakable. I’ve heard mockingbirds croak like frogs, trill like telephones, even imitate hawks (perhaps a bad strategy for long-term survival). Most of the time, they sound like other songbirds.
Not too many days before my pre-dawn concert, a group of us gathered near the visitor center at Pinnacles National Monument.
We heard the unmistakable two-syllable call of the red-tailed hawk. You almost certainly know the call, too. Since they’re relatively common raptors in our area, we hear their calls almost whenever we leave town. But it’s also Hollywood’s favorite for any bird. While eagles have a high, chittering call, most film directors insist that in movies, they should sound more like red-tails, so they do.
We craned our necks, but could not spot that hawk. Then, one of us with sharper ears traced the source of the sound: a Steller’s jay doing an uncannily accurate impersonation.
I’ve read of ravens who hung around over the restrooms at a national park. They could all perfectly imitate the rush of water that accompanies a toilet flushing.
Then, Monday evening, I received an e-mail from a birder in Sunnyvale, who reported a neighborhood starling that’s a virtuoso. The bird had fooled her with imitations of olive-sided flycatcher (a call usually described as “quick, three beers”), western meadowlark and California quail. This bird, a European native widely regarded as a pest, is nothing less than a feathered operetta.
The why’s of birdsong are pretty well understood. Birds sing to advertise their availability, or to stake out a home patch of territory. Many smaller birds – think chickadees and bushtits – chatter constantly to stay in touch with one another. If one sees danger, a warning note, and all are saved. Still other birds vocalize because of their preferred habitat.
Rails and bitterns are found in dense stands of cattails, tules and the like. They call frequently to maintain contact, since they can only see a few inches around them. Indeed, a bittern’s booming call is one of the loudest in nature.
With researchers taking sound prints and digital recordings in the field, we’re learning more about the structure of birdsong all the time.
Slowed down enough, the skylark’s song even bears a striking relationship to Beethoven’s Fifth Symphony, we now know (at least, according to Gareth Davies via PBS).
But why birds mimic other sounds is a mystery.
What’s to be gained in aping a predator’s call? How about duplicating the sound of a flushing toilet?
In the case of the mockingbird, there is a plausible answer, and a body of evidence to suggest that it’s the correct one.
Mockingbirds collect songs the way many of us do; just learning them as they wend their way through life.
Younger birds have relatively few songs to choose from, while birds that have survived for several years have more impressive repertoires.
Mockingbirds sing primarily to advertise their location and availability to mates. Research suggests that females opt for males with the thickest songbooks.
The reason should emerge as obvious: more songs equals a longer life, which in turn equals a bird that is crafty enough to avoid being injured or eaten and resourceful enough to secure food consistently. That’s a bird that’s most likely to be able to feed a family.
But what of that bird singing outside the window a few nights ago? With fall and the approach of winter, they’re not nesting, but there he was, singing.
That’s still a mystery. And that’s good.
It’s the things we do not know that fire our imaginations, that keep us all coming back to wonder a little more.
