A Logical Step

bird sowerbyJames Sowerby (1757 – 1822)
A Bird with Wings Spread

Ithaca, N.Y.
—It may not kill them outright, but low-level PCB contamination is disrupting the way some birds sing their songs. So conclude the authors of a seven-year Cornell University study published today in the science journal PLOS ONE.

Before the chemicals were banned in the United States in 1979, polychlorinated biphenyls, or PCBs, were widely used in the manufacture of electrical devices because they can withstand extremely high temperatures.

“PCBs are changing behavior in subtle but important ways that we’re only beginning to recognize,” says lead author Sara DeLeon. “The Black-capped Chickadees and Song Sparrows we studied ingest PCBs when they eat contaminated insects. The chemicals appear to mimic hormones and interfere with development in the part of the bird’s brain that governs song and song structure.”

Key among the findings is that song disruption is tied to specific types of PCBs—there are 209 variations, differentiated by the positioning and number of chlorine atoms. DeLeon tested 41 of these variations to isolate their effects.

DeLeon chose five study sites in New York State, including two along the Hudson River that were heavily polluted by PCBs dumped illegally from 1947 to 1977. The other sites were not known to have PCB contamination and tests at an Adirondack Mountains site eliminated mercury as a factor in song changes. At each site she collected and tested blood samples from males of the two bird species, recorded their songs over several field seasons, and analyzed those songs.

“The songs of Black-capped Chickadees and Song Sparrows are very well studied,” DeLeon says. “For example, we know that it’s normal for there to be very, very little variation in the way all Black-capped Chickadees deliver their fee-bee song and the interval between the two notes.
We found the greatest variation among birds in areas with higher levels of certain types of PCBs—their songs just were not coming out right. Since dominant males produce the most consistent songs, this variation could have important biological consequences.”

“Effects of PCBs are extremely complicated,” says co-author André Dhondt, director of Bird Population Studies at the Cornell Lab of Ornithology. “What this demonstrates is that most previous PCB studies may not give us the whole picture because they did not look at the specific type of PCB involved but just measured overall levels.”
It took about three years just to complete the chemical analyses.

The next logical step, Dhondt notes, would be to use this method to study low-level PCB effects elsewhere to learn how the pollutants are being spread through ecosystems and the effects they could be having.

 

Other co-authors include research associate Ralph S. Hames; assistant professor of ecology and evolutionary biology André Kessler; and Timothy DeVoogd, professor of psychology, all from Cornell.

 

http://www.news.cornell.edu/stories/2013/09/even-low-level-pcbs-change-bird-songs

This study was funded by: New York Sea Grant; Cornell University Biogeochemistry and Environmental Biocomplexity Small Grant; Cornell Travel Grant; Mellon Grant; Kieckhefer-Adirondack Grant; State University of New York Fellowship;  SLOAN Fellowship; and a Tibor T. Polgar Fellowship.

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6 CommentsLeave a comment

  1. chilling isn’t it

  2. Thank you so much for this information.

    Have had a few Sowerbys in my collection from time to time but one of my earliest memories as a child was my parents introduction of me to Cornell”s Dept. of Ornithology where I learned the basics of identifying frogs, toads, birds and the like as well as their beautiful songs. A precious experience.

  3. “The chemicals appear to mimic hormones and interfere with development in the part of the bird’s brain that governs song and song structure” This is what happened to both bankers and politicians, i guess.

  4. […] A Logical Step […]

  5. We are such arrogant fools, we humans.

    After reading your piece, thinking of my children, I started looking up the effects of PCBs on humans, and I see that as its hard to measure, it hasn’t been done http://pubs.acs.org/subscribe/archive/ci/31/i12/html/12schmidt.html

    • Oh—There are an overwhelming number of threatening substances we’ve integrated into our lives without care or understanding. I never can comprehend how that is considered acceptable, especially when there is substantial doubt about their safety from the start.


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