Dawn chorus of birds makes spring really sing
Jerry George
Saturday, April 12, 2008
Daytime robin song is nothing compared with the dawn chor...
Take my word for it: Inside each of us is one venerable gene that causes most of us to go plumb gaga over spring. It's double dominant in me.
The thing that sets my synapses sparking isn't the clean, crisp, fresh-laundry smell of a spring morning or the first Douglas iris that bursts into bloom like a firecracker above the still soggy ground. Yeah, both are special. But what triggers my chest to swell with the breath of new life is a phenomena birders call the dawn chorus.
Every year songbirds gather in places where insects are plentiful to make and raise new generations - and sing. The woods are full of their seemingly happy twitters throughout the day, but what we hear most of the day is incidental, whistle-while-you-work bantering compared with the symphony of birdsong that greets the dawn.
If you want to experience one of the great treats of nature, take yourself to any tree-shrouded waterway an hour before sunrise. Don't cheat on the time. The chorus is best experienced when you hear the whole show.
In Northern California, the chorus begins with a robin solo. Long before there is the least hint of daylight, you'll hear a robin call out to the world.
In the first weeks of spring, the robins seem tentative. Their calls are muted like they're talking to themselves or mumbling as if they fear that someone or something will notice them. But soon the robins begin declaring their claim on turf or suitability as mates.
The "song" sounds wonderfully melodic to human ears. I wonder, though, whether the male robin's not-so-subtle shout plays the same in the brain of a female robin. Could it come across like a punch-drunk Rocky Balboa shouting, "Yo, Adrian!" Or, you reckon, more like a Placido Domingo aria?
However these birdsongs play, they're important. The dawn chorus is celebrated by songbirds all over the world every spring morning.
As light comes to the world each day and as the season lengthens, more and more birds join in. By a half hour after dawn in late April, hundreds of birds have joined the feathered choir.
Then, responding to an environmental signal not yet recognized by biologists, the chorus stops.
The dawn chorus, no matter where I might be, works better than any alarm clock. With the first trill of the robin, I'm awake and listening for each new voice lending its song to the harmony.
You would imagine that with the dawn chorus as universal and dramatic as it is, scientists would be drawn to it, and they have been, but it wasn't until recently that the scientists finally began to sort out which birds sing when and why.
Years ago, when the dawn chorus was first described, bird-watchers speculated that the first singers had to see well in the dark. Shouting out to the world, "Here I am and I'm very cool," is not the best strategy for hiding from a hungry owl.
So the thought back then was that the first singer had to have big eyes that gather a lot of light to see predators coming.
It sounded like a good explanation, but it went untested until recently, when scientists recorded when each type of bird sang, measured its eye size and also recorded the lumens of light when the birds first burst into song.
Sure enough, the robin has big eyes, and the little tweeters that join in later have smaller eyes.
One puzzle solved.
The other part was easy. Careful observation showed that the chorus was mainly male. When it's spring, what does a young man's fancy turn to? Love.
No surprise, it's the same for birds. In early spring, before mating, the males are out for mates. But the dawn chorus continues after mating. What then?
Turf. Territory.
Territory, whether for mating, nesting or feeding, is always a motivator in birdsong.
Birds don't have handy "Keep Out" signs to put on their personal tree or shrub, so they say it in a song. Again, what appears to our ears as melodious and pleasant, may be heard quite differently by other birds.
Knowing that scientific reality, however, does not change my emotional reaction on hearing the glorious squawking, squeaking, twittering, all mixed together, sometimes hundreds of different voices, as the feathered choir members fill their leafy cathedral with a celebration of the coming day.
To me, every dawn chorus is like Beethoven's Ninth Symphony, an "Ode to Joy."
Freelance writer "Digger" Jerry George sends his journal "letters" home to the Bay Area wherever he happens to be observing nature. He has come to rest for the time being on the Swinomish Indian reservation in the Puget Sound. E-mail him at home@sfchronicle.com.
http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/04/12/HOC21030E8.DTL
This article appeared on page F - 5 of the San Francisco Chronicle
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