I Know Why the Polluted Bird Sings

Photo: Paul Carter / Wikimedia Commons/Wikimedia Commons

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For a generation, scientists have documented the problems that pollution can cause wildlife. Particularly, the many ways that toxic chemicals interrupt, disrupt and prevent wildlife from reproducing has been a key part of research, and it has even been used to argue for strict cleanup standards at polluted sites. The most famous example is probably the bald eagle, the eggs of which were made so brittle by the pesticide DDT that they crumbled under the weight of the birds trying to incubate their brood.

Now, for the first time, scientists have identified how European starlings have greater success mating precisely because of high levels of pollution. It seems that males exposed to endocrine-disrupting chemicals that mimic female hormones are brain damaged, but in such a way that they can develop longer and more complex songs.

The ladies love it, and so the more polluted starlings get it on more often.

“This is the first evidence that environmental pollutants not only affect, but paradoxically enhance a signal of male quality such as song,” said Katherine Buchanan, a Cardiff University scientist and author of the paper, published in the Public Library of Science. “These results may have consequences of population dynamics of an already declining species.”

Starlings are a species native to Europe introduced to New York's Central Park by a man who wanted all birds mentioned in Shakespeare's plays to live in Central Park. While biologists and bird lovers regret that decision, the bard might have smiled on recent research showing that starlings may be the only species other than humans to use grammar in their impressively complex songs.

The more complex, the better. But the vocal ability enhanced by synthetic and natural estrogens imbibed in polluted earthworms comes at a cost, not only to the birds exposed, but possibly the entire population.

The immune systems of these birds is also compromised by the pollution, according to the research. And because the birds that both sing well and get sick reproduce more frequently, that means the birds are more likely to produce sickly offspring, potentially affecting the survivability of the entire species.

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