Sep 14 2009

A Sound Like Spring Peepers

Published by at 7:04 am under Migration,Songbirds

Swainson's Thrush (photo by Chuck Tague)

Yesterday morning I stepped out on the front porch just after 6:00am to check the weather.  It was my first morning home from Maine and I was a little surprised that I didn’t need a jacket and the sun hadn’t come up yet.  What was I thinking!  Maine is certainly colder and it’s so far east that the sun rises there 45 minutes earlier than it does in Pittsburgh.  I had nearly an hour to wait for dawn.

As I gazed at the waning moon I heard a sound like spring peepers coming from above.  I knew the distinct solo “peeps” were the nocturnal flight calls of migrating thrushes, but which ones?

The pre-dawn sky was clear with a light wind from the north.  The birds kept coming with hardly a pause.  I rushed indoors to get my binoculars but it was too dark to see the birds.  In my excitement I forgot to count the sounds so all I can tell you is that they passed by steadily for 20 minutes.  My guess is there were several hundred of them. 

Later indoors, I checked my birdsong CDs and the Internet for samples of nocturnal flight calls.  I couldn’t find any audio examples – only voice-prints – but I looked through descriptions of various thrushes’ calls and found this at the All About Birds description of the Swainson’s thrush:  “Nocturnal flight call a “peep” similar to a single note from a spring peeper frog.”

So that’s who they were. 

I heard Swainson’s thrushes migrating this morning as well.  I wish I could have seen them.

(photo by Chuck Tague)

3 responses so far

3 Responses to “A Sound Like Spring Peepers”

  1. Dianeon 15 Sep 2009 at 7:53 pm

    Kate, I don’t understand what you would be doing by counting the sounds. Is that a way to count the number of birds?

  2. Kate St. Johnon 15 Sep 2009 at 10:59 pm

    Counting the sounds sort of counts the birds. Granted, I can’t figure out which bird is making which sound in the dark but if I estimate that I am hearing two “peeps” from the same bird before it passes out of hearing then dividing the count by two would give me the number of birds. I don’t know the ratio so my calculation would be inaccurate but Cornell has published a study on it: http://www.birds.cornell.edu/brp/research/nocturnal-migrant-flight-call-research

  3. Dianeon 15 Sep 2009 at 11:11 pm

    Very, very interesting. Thank you.

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