Owl Populations Change Color as the World Warms

Across Eurasia, brown tawny owl populations are growing as the climate changes, researchers report.

The medium-sized, tree-nesting owls usually have gray or brown feathers; their genes determine their color. Historically, there were more gray owls than brown in Finland, where the researchers conducted their study based on 30 years of data. Now, the populations are about even, the scientists concluded in a paper recently published in Nature Communications.

During harsh winters that blanket the ground with snow, gray tawny owls fare better, possibly because brown tawny owls are more visible to predators. As winters have become milder, snow cover has decreased, and brown tawny owl populations have increased.

"Its survival has improved as winters have become warmer," lead researcher Patrik Karell, who is with the Bird Ecology Unit at the University of Helsinki, told the BBC News. "In other words, climate-driven selection has led to an evolutionary change in the population."

The study shows that climate change could affect genetic diversity--especially if the warming trend continues as expected--helping to answer the question of how a hotter planet could affect species around the world.