Polluted prey causes wild birds to change their tune

February 26, 2008

Considerable attention has been paid to the effects of endocrine disrupting chemicals in aquatic environments, but rather less attention has been given to routes of contamination on land. A new study, published in PLoS ONE on February 27 by researchers at Cardiff University, reveals that wild birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour: male birds exposed to this pollution develop more complex songs, which are actually preferred by the females, even though these same males usually show reduced immune function compared to controls.

Katherine Buchanan and her colleagues studied male European starlings (Sturnus vulgaris) foraging at a sewage treatment works in the south-west UK and analysed the earthworms that constitute their prey. The researchers found that those birds exposed to environmentally-relevant levels of synthetic and natural estrogen mimics developed longer and more complex songs compared to males in a control group.

Specifically, birds dosed with the complete spectrum of endocrine disrupting chemicals found in the invertebrates spent longer singing, sang more often and produced more complex songs, a sexually selected trait important in attracting females for reproduction even though birds dosed at these ecologically relevant levels also showed reduced immune function.

The study also addresses the mechanism for this effect, as the researchers found that the high vocal centre (HVC), the area of the brain that controls male song complexity, is significantly enlarged in the contaminated birds. Estrogen causes masculinisation of the songbird brain and the HVC is enriched with estrogen receptors. Neural development is thus susceptible to exposure to chemicals which mimic estrogen, or to enhanced estrogen levels. The results also confirm the plasticity of the adult songbird brain.

Finally, the scientists found that female starlings prefer the song of males exposed to the mixture of endocrine disrupting chemicals, suggesting the potential for population level effects on reproductive success.

"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, the corresponding author of the paper. "These results may have consequences of population dynamics of an already declining species."
-end-
Disclaimer

The following press release refers to an upcoming article in PLoS ONE. The release has been provided by the article authors and/or their institutions. Any opinions expressed in this are the personal views of the contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the release and article and your use of such information.

Citation: Markman S, Leitner S, Catchpole C, Barnsley S, Müller CT, et al (2008) Pollutants Increase Song Complexity and the Volume of the Brain Area HVC in a Songbird. PLoS ONE 3(2): e1674. doi:10.1371/journal.pone.0001674

PLEASE ADD THE LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF YOUR REPORT (URL live from Feb. 27): http://www.plosone.org/doi/pone.0001674

PRESS-ONLY PREVIEW OF THE ARTICLE: http://www.plos.org/press/pone-03-02-buchanan.pdf

PLOS

Related Estrogen Articles from Brightsurf:

Removal of synthetic estrogen from water
Synthetic estrogens from pharmaceuticals contaminate rivers and threaten the health of humans and fish.

Does estrogen influence alcohol use disorder?
A new study from researchers at the University of Illinois at Chicago shows that high estrogen levels may make alcohol more rewarding to female mice.

Estrogen's role in the sex differences of alcohol abuse
Fluctuating estrogen levels may make alcohol more rewarding to female mice, according to new research in JNeurosci.

Estrogen's opposing effects on mammary tumors in dogs
Estrogen's role in canine mammary cancer is more complex than previously understood, according to new research led by the University of Pennsylvania School of Veterinary Medicine.

Placenta transit of an environmental estrogen
The human foetus is considered to be particularly sensitive to environmental contaminants.

Estrogen improves Parkinson's disease symptoms
Brain-selective estrogen treatment improves the symptoms of Parkinson's disease in male mice, according to new research published in JNeurosci.

The sneaky way estrogen drives brain metastasis in non-estrogen-dependent breast cancers
University of Colorado Cancer Center study shows that while estrogen doesn't directly affect triple-negative breast cancer cells, it can affect surrounding brain cells in ways that promote cancer cell migration and invasiveness

New study demonstrates effectiveness and safety of vaginal estrogen
Despite its proven effectiveness in treating the genital symptoms of menopause, low-dose vaginal estrogen therapy remains underused largely because of misperceptions regarding its safety.

Hidden estrogen receptors in the breast epithelium
EPFL scientists have uncovered that next to estrogen receptor positive and negative there are cells with very low amounts of the receptor protein.

Estrogen may protect against depression after heart attack
Estrogen may protect against heart failure-related depression by preventing the production of inflammation-causing chemicals in the brain.

Read More: Estrogen News and Estrogen Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.