Sunday, April 20, 2008

The Fascinating Sounds of Birds

My favorite science story of the week comes from the latest book I just finished, The Singing Life of Birds.

The Singing Life of Birds: The Art and Science of Listening to Birdsong
by Donald Kroodsma

Read more about this book...

I came upon this book as Donald Kroodsma, the author, was the guest speaker at the annual banquet of our local Audubon chapter - Golden Eagle Audubon Society. He spoke of his life long research into vocal communication of birds. His enthusiasm was amazing, I got the feeling he could talk about this for days. The evening content was an interesting introduction to the detailed content presented in the book. While his science is in-depth and detailed, his presentation both in person and in the book is tailored toward the non-scientist. It's an easy and interesting read into the unique structure of bird song and how it varies between different species.

The book has clearly increased my awareness to the complexities of bird song. Since I began reading the book, I have noticed my own attention to bird song details has changed. The other day while walking downtown I listened to different House Finches singing from their territory. I noticed them answering back to each other. I noticed when they made subtle changes in their song. Drawing real conclusions about their communication would obviously require in-depth research, but at least I was now appreciating more about the song. In another example, while walking back form dinner downtown, I picked out a European Starling mimicking a California Quail. The subtlety would have been lost on me a week before. Any book that has a this dramatic of an impact on my awareness, is well worth the price tag. I obviously recommend this book highly.

The author covers many different species in the book and highlights the unique aspects of each.  Each specie that he covers has some underlying structure to its song. Details such as whether a particular male would sing the same song back to back, whether a neighbor would match a song of a neighbor, whether a song bird learns the songs of his father before dispersing or picks it up from his new neighbors after dispersing, etc.

Now to the favorite story of the week. While all of the bird stories are fascinating, I found his coverage of Song Sparrows the most interesting (pages 55-67). Song Sparrows have a large number of songs that they learn over their lifetime. They also maintain common songs with their neighbors, but not necessarily the same song for each neighbor. Its how they use these songs that I found particularly fascinating. When addressing a particular neighbor, the Song Sparrow almost always chooses a song that the two of them share. This proves knowledge of which neighbors know which songs. When answering a neighbor, there are three ways to respond, with the same song, within another that the two share, or with one that the other does not share. As stated earlier, a song that the two does not have in common is rarely used. Kroodsma noticed that a Song Sparrow responding with the same song caused an increase in aggression and responding with a different song causes tension to decrease. As a result the song sparrow has a number of choices to make when communicating with a neighbor. He first must consider the songs that he has in common with the neighbor, and then choose a match to that last song sung by the neighbor to increase aggression, maybe to enforce a territorial boundary, or a non-match to decrease the tension. The complexity grows when you realize that each bird's territory is surrounded by many other territories. It was interesting but not surprising that he also proved that a juvenile joining this community will pick up on the songs that he hears multiple other birds singing.  Just one view into the type of study covered in the book.

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1 comment:

John said...

I read this book about a year ago, and I loved it.