The Dawn Chorus

Some of my earliest and sweetest memories are of awakening at daybreak to the sound of a robin singing outside my window.  The robin’s repetitive call was easily recognizable to me, yet it wasn’t until I reached adulthood that I fully realized that his voice was but one of a host of birds singing each spring morning to create the natural phenomenon known as the dawn chorus.

What is the dawn chorus?  Here in the northern hemisphere, it is a temporal event that takes place over a period of days and weeks every spring, but it also one that is recreated every morning during that period.  It is the voices raised by a multitude of male birds to attract mates and claim breeding territories.

The first songs to be heard each vernal season are of “resident” bird species that live here year round, later to be joined by the neo-tropical migrants who fly in for summer from their wintering grounds in Central and South America. 

Where I live, the dawn chorus starts to build in early March with a few “in-house” voices: the robin’s sing-song cadence, the chickadee’s gently pleading fee-bees, the Bewick's wren's loud staccato, the spotted towhee's assertive rattle, and the junco's ticker tape trill. 

In mid-March, Violet-green and Tree swallows start chittering their joy and verve into the skies above my house, while vehemently discussing just who will be occupying the specially-designed swallow box mounted beneath my carport roof. 

As the calendar advances into April, I delight in noting the aural return of my old friends the warblers and flycatchers: especially the Orange-crowned Warbler’s downward trill, the Black-throated Gray’s zeetle, zeetle, zeetle, ZEET, the Western Wood Peewee’s raspy peer, and the Pacific Slope Flycatcher’s attention-grabbing See-oo-EET! whistle. 

As spring bird migration progresses further, I listen intently for all the familiar vocalizations.  It is only when I hear the Black-headed Grosbeak's jazzy improv, the Western Tanager's clever robin imitation, and the Swainson's Thrush's "Doink!", whinny, and ethereal, spiraling reverberations, that my heart gains its ease, knowing that all the eagerly awaited sojourners are present once again.

On a daily basis, the dawn chorus actually begins before any light is discernible by the human eye, around 4:30 a.m.  Yet the birds must see it. One study found that the opening verses of the dawn chorus are sung by the bird species with the largest eyes.

But why do birds sing at or before dawn? Here is a good explanation from Yahoo Answers as to why male birds choose the hours nearest sunrise to warble their arias:

Dawn is the best time to sing because the air is generally calmer and sound transmission is good. A dawn song is thought to be 20 times more effective than singing at midday and at dawn, birds can do little else. Light is poor and insect prey is not flying, so foraging for food is difficult. Also, female birds generally lay eggs in the morning, so a dawn mating is the best time for a male. Finally, if any birds have died overnight, the others will know where there is a vacant territory.

I am fortunate to live in good bird habitat; near a large wetland and surrounded by forest edge vegetation.  In my first years of residency at this location I would sometimes rise early on a spring morning and stand on the bank behind my house to listen in awe and appreciation to the beautiful swelling symphony that is the sound of the earth singing.

Yet over time as land development and habitat destruction has occurred in my neighborhood, that composition, while still robust, has diminished in nature and become slightly harder to distinguish. Studies have shown that birds nesting in urban in areas must now sing louder than normal to be heard above our human-created cacophony, especially that of traffic noise. Situated as I am near several big box stores and I-5, the birds have to “shout” to be heard.  There are also concerns about light pollution’s effects on birds, which may cause them to confuse night for day and sing when they should be sleeping.

There are many ways to enjoy the Dawn Chorus.  My sister recalls a birding class she taught several years ago.  She took her students on an early-morning field trip to Ellis Cove at Priest Point Park to hear the dawn chorus. She says the experience was unforgettable.

There must be many other similarly great places in Thurston County to hear nature’s majestic chorale.

I have taken to video-taping the dawn chorus on my camera and playing back the recordings, especially during the mid-winter months to remind myself that the season of darkness inevitably gives way to the season of light.

The dawn chorus is available on CD.  Lang Elliott is a “nature recordist, photographer and author” whose works I have enjoyed.  I found his book Music of the Birds: A Celebration of Bird Song fascinating.

One of my favorite movies, the 2005 version of Pride and Prejudice with Keira Knightly, utilizes birdsong to wonderful effect.  In some early scenes, the voice of a single male bird serenades Lizzie, clearly foreshadowing her and Darcy’s ultimate pair-bonding in the gorgeous English countryside to the exultant strains of the dawn chorus.

There is even an International Dawn Chorus Day which is being held on Sunday, May 6 this year.

150 years ago, Henry Wadsworth Longfellow wrote these lines about this amazing natural event:

Think every morning when the sun peeps through
The dim leaf-latticed windows of the grove,
How jubilant the happy birds renew
Their old, melodious madrigals of love!
And when you think of this, remember too
'Tis always morning somewhere, and above
The awakening continents, from shore to shore
Somewhere the birds are singing ever more
Yearly, the dawn chorus grants us the chance to remember that the earth belongs to all creatures, not just us. That this shining globe, hurtling through the inky blackness of space, burgeons with countless forms of life whose only desire is to not be silenced. Our task as humans is to learn to be worthy of this benediction.

I am so thankful that I can still awaken to the song of the robin outside my window.  My fervent hope is that we all continue to have this opportunity, "ever more".

Words and photos by Nancy Partlow

Videos:
Dawn Chorus In Tumwater, May 2011

Resources:
Yahoo Answers UK & Ireland on the Dawn Chorus:
http://uk.answers.yahoo.com/question/index?qid=20070727110559AAyYo72
Nature UK on the dawn chorus:
http://www.bbc.co.uk/nature/uk/indepth/dawn-chorus.shtml
Eye size in birds and the timing of song at dawn:
http://rspb.royalsocietypublishing.org/content/269/1493/831.abstract
How noise pollution is driving out birds from towns and cities: http://www.dailymail.co.uk/sciencetech/article-546488/End-dawn-chorus-How-noise-pollution-driving-birds-towns-cities.html
Lang Elliott's site: http://www.musicofnature.org/home/

Migration begins

    It is early April.  Long streaming days of cold, wet and depressing weather have sent us fleeing  north for spring break to the area around Sequim.  Here there is a rain shadow from the Olympic mountains and here, too, we might find surcease from this hideous spring. And so it has proved.

Striped Peak

    We are sitting at Salt Creek  campground along the Strait of Juan de Fuca, where we stopped for a bathroom break.  The heavy rain & slashing winds of the night before have broken open, and we have been enjoying some strong spring sunshine.  Sitting  east of us in the near distance is Striped Peak,  one of the last foothills of the Olympic Mountains before the cold waters of the Strait devour its base.   I was sitting in the car, idly glancing around, when I saw a couple of Bald Eagles soaring over the peak.  There was a mad scramble for binoculars (both pairs!)  and then jostling for the  best viewing place.  Binos glued to our faces, we called out sightings and descriptions back and forth: “No, look, look, to the left of the peak, see that scraggy tree, just above it.  Ooooooh look, there’s another one!”  As we watched, a thermal updraft formed, and  migrating hawks raced to catch it.  This is spring hawk migration along the Strait.  For me, it took me back 22 years to Cape Flattery and other April raptor migrations I have watched.

          Here in western Washington state, the birds of prey are making their migration move north.  It is the Red-tailed Hawks, the Bald Eagles (and occasional Golden Eagles),  the falcons,  the accipiters like Sharp-shinned and Coopers Hawks, and others that leave their winter territories in the southern lands and follow the Pacific coast line north.  Some stop in Washington state, and set up breeding territory,  but many more push through to Canada and into Alaska to find their place, their mate and rear this year’s young.  

Crossing the cold water to Vancouver island

     A big challenge for these birds is the Strait of Juan de Fuca.  A frigid body of salt water, it forms the northern border of Washington state, sharing its waters with Canada.  They have to cross it to get north.  It can be as much as 15 miles across to Vancouver island, and it takes strong flight muscles to get a bird across without getting pulled down into 40 degree water.  Falcons can do it:  I’ve seen both Peregrine and Merlins get a fine head of steam and just power themselves across on the strength of those oar-like wings.  But surprisingly, most of the other common travelers are fairly weak flyers over long expanses of cold water.  They need to find another way. 

A Red-tailed hawk, wings set to ride the thermal

     The strategy they use is to ride the “thermal elevator”.  Thermals are updrafts of warm air that rise from the ground and can go many thousands of feet into the air.  Thermals form a spiral, rising column of air; the hawks and eagles somehow feel out these currents.  They set their wings to glide and allow the warm air to lift them to great heights.  Along the Strait of Juan de Fuca, they get to a certain height, then set their wings to glide north.  They then simply slide across the next fifteen miles, gradually losing elevation and arriving on Vancouver island, ready to rest and feed and prepare for the next leg of the journey.

     I first learned about all this from Bud Anderson, falcon biologist and educator extraordinaire, who discovered this Strait of Juan de Fuca spring migration phenomenon  further west near Neah Bay, at Cape Flattery.  It was with Bud and his Falcon Research Group volunteers that I spent several early Aprils, on a low mountain near Neah Bay, watching the hawks, falcons and eagles head north.  After the research project ended, I really missed seeing the migration.  So what happened for us this week was a real treat.

    What we saw at Salt Creek  was several factors that came together to make the thermal elevators possible.  For example, the hot spring sun had been warming up Striped Peak, but unevenly: one warm side of the hill with one cold side sets up the spiraling updrafts.  In addition the peak sits right on the cold water of the Strait, which adds its own complexity to the thermal recipe.  There was a weak southeast wind;  from my years at Neah Bay I remembered that east winds along the Strait really aid in the formation of thermals.   In addition, Striped Peak is near the narrowest point of crossing to Vancouver island - about 10 miles. If I’m a hawk and the day’s conditions are questionable, I’m going to pick the shortest crossing.

Look closely:  hawks soaring above the trees

     As we watched these raptors over Striped Peak, we noticed others coming to join them.  I remember Bud teaching us that all of these spring migrants are hot to trot, ready to cross the water and get down to business.   So they sit in trees near the Strait, waiting for good conditions and also watching each other to see if another migrant has found a great thermal elevator.  If it looks promising, they race to join it.  Thermals are very ephemeral, and the birds have to move fast to get on the elevator.  Today we were seeing that same thing;  a small group of two or three quickly became  six, then nine.  These groups of circling hawks are called “kettles”, which refers to the way they look like they are circling in a soup pot.

       Not all thermals have enough lift to get the birds high enough to cross.  Today we watched the birds in the kettle shift and adjust, trying to find the best spots.  The thermals did not seem to generate enough lift for most of the birds, although Glen was certain he saw one bird gliding over the Strait.  By about 2:30 clouds were covering the sun and the thermal elevators shut down for the day.   The birds dispersed and disappeared. 

Sunset along the Strait

    
      We headed back to our snug berth along the Dungeness Spit.  The heavy clouds turned to rain and then broke briefly for a beautiful sunset.  I thought about the hawks, now settled down in a tree somewhere along the water’s edge.  Hopefully they found a fish, a vole, a small bird to eat before the cold night ahead.  They will wait for morning, for better conditions, to try again.    

     I fall asleep and dream of them, wheeling, rising and turning, disappearing into the mist, making safe passage north to home...

Janet  

Resources
•  Falcon Research Group:  www.frg.org
•  Red tailed Hawk Photo by Ellen Wilson.  See her blog at: http://www.wilsonswordsandpictures.com/
•  All other photos by Glen Buschmann