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.

Cornell Lab of Ornithology

english songbird

Ithaca, N.Y.— In one of the greatest feats of endurance in the biological world, millions of tiny songbirds—many weighing less than an ounce—migrate thousands of miles to Central and South America each year. Now scientists are finding out how these featherweights do it: using elliptical routes that take advantage of prevailing wind patterns to save calories.

By shifting routes, birds are taking advantage of stronger tailwinds in spring and less severe headwinds in fall, a study has found. Tailwinds represent a huge advantage for birds heading back to their breeding grounds, while finding weaker headwinds in fall allows southbound birds to make the best of a bad situation.

The analysis also revealed that many more land birds than previously realized follow different routes in spring and fall—particularly in the East, where many species cross the Gulf of Mexico in a single overnight flight.
Many species in the Eastern and Central groups take southbound routes far to the east of their northbound routes, resulting in a clockwise migration loop that puts some of them out over the Atlantic Ocean on their way to their wintering grounds.

The findings may help refine ideas about how and where to plan for conservation along migratory pathways.

“All these species migrate at night, at high altitudes, where we can’t see them,” said Frank La Sorte, a Cornell Lab of Ornithology research associate. “But when the sun comes up in the morning they have to find somewhere to land . . . . “

La Villa di Livia

vl det
The very kind and very, very patient alicelucie of mellifluous name and the blog “All I Love” —which encompasses a good deal of the things I lovenominated  TSG months ago for something called the Liebster Award. I can’t excuse or explain why it’s something I wasn’t up to dealing with at the time, but —

Some Really Great Blogs I recommend in turn:

pastnow
History, Arts, and Stuff

FORMAL DIVISIONS and SURFACE PATTERNS
rhythm / pattern / texture / surface /  line / shape / process / revision / decay / becoming

Next stop: Science
The perks of being a PhD student

stOttilien
Religion – Philosophy – C.G. Jung and Cultures

Origins of Science as a Visual Pursuit

Critical Environmentalism
Social Studies of Environmentalism

Teenage Conservationist

The ROYAL SOCIETY has a blog!
http://blogs.royalsociety.org/history-of-science/

Discover Smithsonian Gardens
http://smithsoniangardens.wordpress.com/

To advance the understanding of nature & to engage people of all ages in learning about birds & protecting the planet.
The Cornell Lab of Ornithology
http://www.birds.cornell.edu/page.aspx?pid=1609

Conservation Status: Least Concern

oven birdRue
Jacques le Moyne de Morgues (1533 -1588)

 

The Oven Bird

There is a singer everyone has heard,
… Loud, a mid-summer and a mid-wood bird,
Who makes the solid tree trunks sound again.
He says that leaves are old and that for flowers
Mid-summer is to spring as one to ten.
He says the early petal-fall is past
When pear and cherry bloom went down in showers
On sunny days a moment overcast;
And comes that other fall we name the fall.
He says the highway dust is over all.
The bird would cease and be as other birds
But that he knows in singing not to sing.
The question that he frames in all but words
Is what to make of a diminished thing.

Robert Frost (1874 – 1963)


A small, inconspicuous bird of the forest floor, the Ovenbird is one of the most characteristic birds of the eastern forests. Its loud song, “teacher, teacher, teacher,” rings through the summer forest, but the bird itself is hard to see.
Neighboring male Ovenbirds sing together. One male starts singing, and the second will join in immediately afterward. They pause, and then sing one after the other again, for up to 40 songs. The second joins in so quickly that they may sound from a distance as if only one bird is singing. Ovenbirds rarely overlap the song of their neighbors.
http://www.allaboutbirds.org/guide/Ovenbird/sounds