EPOW - Ecology Picture of the Week

Each week a different image of our fascinating environment is featured, along with a brief explanation written by a professional ecologist.

7-13 July 2003

Click on the image to hear the song (MP3)

Colorful Songs in Your Back Yard


Sound spectrograms of songs of
Song Sparrow (Melospiza melodia)

Credit & Copyright: Dr. Bruce G. Marcot

Explanation:   What looks like artwork from the New York School of Abstract Expressionism is actually "sound spectrograms" of bird songs.  More specifically, these are three different songs from a single bird, a Song Sparrow, singing in a back yard outside Portland, Oregon, one fine Spring afternoon.  Click on each image above to hear the song (MP3) that made the picture.  

What are these pictures?  Sound spectrograms are plots of the frequency of the sound on the vertical axis (measured in cycles per second or Hertz, abbreviated Hz), against time along the horizontal axis.  Ornithologists learn to "read" these sound spectrograms just as musicians can read musical scores and hear the music in their heads.  Yes, it takes practice.

Song Sparrows are common birds of yards and streamsides.  Their songs, very well studied, consist of a series of set phrases and notes stitched into various combinations.  Their songs usually start with 3 or so introductory notes, as shown in the above examples.  Above are three very distinct songs out of an uninterrupted series of more than 50 songs sung by one individual bird over the course of a half hour or so.  Nearly every song was different, with some variation in the sequence and types of notes!  

Birds sing for territoriality, to find and keep mates, to learn to communicate, and -- as we silly humans would think -- probably for sheer joy.   We can really begin to appreciate songbirds when we greatly slow their sounds ... for example, here is the sound (MP3) of the last song above, slowed 4 times normal speed.  Listen for the overtones, overlapping notes, and abrupt changes in pitch and cadence.  Even the most amazing human singer could never match this!

Next week's picture:  Sharptail Snake

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