Archive for the 'Vocalizations' Category

Dec 19 2012

Named For…

Guess why this South American bird is called a Bearded Bellbird.


(video from YouTube)

p.s. that beard is not made of feathers.  It’s long stringy skin.  :-o

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Dec 07 2012

Hiding By Voice

Have you ever noticed how hard it is to find a bird when it’s making an alarm call?  And how easy it is to find when singing?

It’s not just that birds hide when alarmed and sing out in the open.  They change their tune to conceal or reveal.  They know that the “physical structure of a sound affects the ease with which a listener — predator or neighbor — can locate its source.” (*)

Northern cardinals are a great example of this principle.

When they’re hiding in a thicket, their call is a thin, faint, high note.  The alarm call’s narrow frequency range makes it really hard to pinpoint.  Click here for an example.

By contrast, when they’re announcing their presence or guarding their territory the sound is rich and variable in a wide frequency range.  This gives it a lot more “hooks” for our ears to grab onto.  Here’s an example of their song and contact calls.

So when birds are warning each other of danger, there’s a reason why you can’t find their location.  They’re hiding by voice.

(photo by Cris Hamilton. Inspiration for this Tenth Page is from page 220(*) of Ornithology by Frank B. Gill.)

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Nov 27 2012

Two Levels Of Distortion

Earlier this month I watched a flock of robins and starlings feast on the Bradford pears near Heinz Chapel.  Birds usually don’t sing in the fall but this flock was muttering and whisper-singing.  Three birds in particular caught my ear.

A robin sang softly.
A starling mimicked the robin.
A mockingbird mimicked the starling mimicking the robin.

By the time the robin’s song came out of the mockingbird’s mouth it was nearly unrecognizable.   (Click here for the robin’s song.)

European starlings, on the left above, are considered mimics but they have wiry voices that distort whatever they say.  Here’s a typical starling song. At the 00:32 mark he does a good imitation of a house sparrow. I couldn’t find an audio clip of a starling mimicking a robin.

Northern mockingbirds, on the right, are much better mimics than starlings.  They can follow a robin’s tune and cadence but miss the melodious thrush harmony.  They brazenly mask this deficiency: “I meant to sing the tune without the harmony.”  Click here to hear a mockingbird mimicking many birds, including robins.

The mockingbird at Heinz Chapel clearly copied the starling’s wiry song including his poor imitation of the robin.

It was like a game of telephone.  There were two levels of distortion.

(European starling by Paul Carter via Wikimedia Commons. Northern mockingbird by Dick Daniels via Wikimedia Commons. Click on these imbedded links to see the original photos.)

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Nov 22 2012

Thirty Turkeys

Sometimes, if you’re lucky, you can see a whole flock of turkeys on the move.

In this photo Steve Gosser found 30 of them at Beaver Run Reservoir in 2010.  This fall I saw 16 at Schenley Park.

If you’re quiet you might also hear them calling or gobbling.  Click here and scroll down to hear an assortment of turkey sounds from purrs to explosive gobbles.

Happy Thanksgiving.

(photo by Steve Gosser)

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