The Townsend's Warbler is one of the species that migrates through Texas along the Gulf of Mexico. Credit: Craig Kerns, Cornell Lab of Ornithology.
Key Points:
- New research shows migrating birds attracted by light pollution face higher toxic chemical exposure than their counterparts.
- One region of special concern is along the Gulf of Mexico, especially in Texas and Louisiana.
- Long-term exposure to toxic chemicals can interfere with the birds’ cell and organ function, and contamination can carry over to the young.
For birds, the city lights aren’t tantalizing—they’re life-threatening. According to a new study by Cornell researchers, birds attracted by the glow of artificial light at night are drawn into areas where they are also exposed to higher concentrations of airborne toxic chemicals.
For the study, published in Global Change Biology, the researchers examined the correlation between the concentration of airborne toxic chemicals, artificial light at night, and the weekly abundance of 165 nocturnally migrating songbird species.
They first compared levels of artificial light at night with the presence of 479 toxic chemicals from 15,743 releasing facilities across the continental United States. They found that higher light pollution did correlate with higher levels of airborne toxic chemicals. The scientists then cross-referenced the data with the weekly abundance of 165 night migrating songbird species throughout their annual life cycles, using data from the Cornell Lab's eBird program.
The only time that did not reveal increased exposure to toxic chemicals was during the breeding season when songbirds typically nest in habitats away from areas of intense human activity.
Previous studies have shown that air pollution has caused some species to stop migrating, change migration altitude, or alter their course. Additionally, long-term exposure to toxic chemicals can interfere with cell and organ function, and contamination can carry over to the young through the transfer of chemicals from a nesting female to her eggs.
"Efforts to reduce light pollution during the spring and autumn would reduce the chances of toxic chemical contamination during migration stopovers, which would improve survival and reproductive success," said lead author Frank La Sorte at the Cornell Lab of Ornithology. "However, this would have no effect on the long-term exposure occurring along the U.S. Gulf Coast, a region that could be a significant source of toxic chemical contamination for North American birds."
Information provided by Cornell University.