Cities are getting brighter at night with well-lit crosswalks, sidewalks and paths through parks and wooded areas. Lighting can make it easier for drivers, bicyclists and runners to navigate the darkness safely. But increased lighting has unintended consequences for wildlife, including songbirds.
Just like humans, songbirds are active during the day and sleep at night. Jenny Ouyang, PhD, an associate professor of biology at the University of Nevada, Reno, wanted to know how songbirds’ brains are influenced by exposure to artificial light at night. She presented her research at the 2024 American Physiology Summit as part of a session called “Physiology in a Changing World.”
Ouyang’s team exposed male zebra finches to three different types of light—natural light during the day, darkness at night and artificial light at night—to see how they affected the birds’ brains. The researchers monitored the birds’ activity by using special perches that tracked each time a bird hops on the perch. Exposure to artificial light at night increased the zebra finches’ hopping activity to a similar daytime level, while nighttime darkness led to the least amount of hopping.
Two hours after an extended stretch of being in artificial light, the researchers looked at nerve cell (neural) activity in the birds’ brains. They found that expression of a protein that’s a marker for neural activity was higher after exposure to artificial light at night compared to the nighttime darkness. Brain regions with increased protein expression included areas that control movement, learning and memory and vision.
These findings suggest there are acute changes in zebra finches’ brain activity when they experience artificial light at night. This brings questions to mind such as how these changes in neural activity will shape a bird’s behavior the following day and what the consequences of chronic exposure to light at night may be for wildlife. Also, baby birds might be similarly affected by light at night.
A better understanding of how light pollution at night influences the physiology of wildlife can help city and urban planners decide what colors of light to use in areas birds call home.
Jessica Whitaker-Fornek, PhD, is a postdoctoral fellow in the Pharmacology Department at the University of Michigan. She studies the neural control of breathing in developing birds and mammals.