Polluted Prey Affects Wild Birds

Welsh scientists have found brain and behavioral changes in wild birds after the birds forage on invertebrates contaminated with environmental pollutants.

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

The study found the birds’ high vocal center — the area of the brain that controls male song complexity — became significantly enlarged in the contaminated birds. Neural development is thus susceptible to exposure to chemicals that mimic estrogen, or to enhanced estrogen levels, the scientists said.

The researchers also found 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 Buchanan. These results may have consequences of population dynamics of an already declining species.

The study appears in the online journal PLoS One.