Horned Larks are cute songbirds with white bellies and yellow chins—at least, now they are.
One hundred years ago, at the height of urban smoke pollution in the United States, their pale feathers were stained dark gray by soot in the atmosphere.
A new paper in the Proceedings of the National Academy of Sciences shows that the discoloration of these birds in museum collections can be used to trace the amount of black carbon in the air over time and measure the effects of environmental policy on pollution.
“The soot on these birds’ feathers allowed us to trace the amount of black carbon in the air over time,” said study author Shane DuBay, a graduate student in the Committee on Evolutionary Biology at the University of Chicago and The Field Museum. “We found that the air at the turn of the century was even more polluted than scientists previously thought.
DuBay and study co-author Carl Fuldner, a graduate student in the Department of Art History at UChicago, analyzed more than a thousand birds collected over the last 135 years to determine and quantify the effects of soot in the air over cities in the Rust Belt.
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Image via Carl Fuldner and Shane DuBay