Eastern Screech owls can be gray or red, the red known as "rufus" screech owls, Baylor University researcher Fred Gehlbach said.
Rufus screech owls primarily are found in hot and humid areas in the southern United States and have porous feathers that dissipate body heat. Gray screech owls primarily are found in rainy cloudy areas and have stouter feathers to protect against the cold.
In the last 20 years, rufus owls have increased from about 7 percent of the total eastern screech owl population to about 15 percent and likely will continue to increase as temperatures warm, Gehlbach said in a release Monday.
Rufus owls also have been nesting, or breeding earlier, he said. In central Texas, the birds have been observed nesting about a day earlier every three years.