The bright lights of big cities could be causing an evolutionary adaptation for smaller eyes in some birds, a new study indicates.
Researchers found that two common songbirds, the Northern Cardinal and Carolina Wren, that live year-round in the urban core of San Antonio, Texas, had eyes about 5% smaller than members of the same species from the less bright outskirts. Researchers found no eye-size difference for two species of migratory birds, the Painted Bunting and White-eyed Vireo, no matter which part of the city they lived in for most of the year.
The findings, published in Global Change Biology, have implications for conservation efforts amid the rapid decline of bird populations across the U.S.
Read more at: Washington State University
Photo Credit: GeorgeB2 via Pixabay