EVANSVILLE, Ind., July 30 (UPI) -- The nine-banded armadillo is quietly expanding its range out of the southeastern United States, invading regions once too cold for the small mammal to survive.
Scientists monitoring the armadillo's progress say the migration is a consequence of rising global temperatures. And it's a sign of more to come.
"Armadillos are a pretty good climate change indicator species," said John MacGregor, a herpetologist at the Kentucky Department of Fish and Wildlife. "When things that don't tolerate cold climates are suddenly appearing in a cold area, it tells me that area is getting warmer."
The armadillo's expansion across the country started slowly, but it's picking up speed. The animal made its first appearance in western Kentucky in the early 1980s, MacGregor said. By the early 2000s, sightings became yearly occurrences.
Today, armadillos are common across Kentucky -- and they keep marching north. They've been sighted in Indiana, Illinois and Nebraska. They could eventually reach as far north as New England, according to the National Wildlife Federation.
This means that the climates in these regions are changing considerably.
"What knocks armadillos back is very long, cold winters," MacGregor said.
Those kinds of winters are occurring with less frequency in the Midwestern United States, said Petra Zimmerman, a climatologist at Ball State University, in Indiana.
"Globally, it's getting warmer," Zimmerman said. "So, temperatures in the Midwest are also increasing. We've seen some incredibly warm winters in the last few years. They were record-breaking years, and they were breaking the record from the year before."
Global warming is linked to carbon emissions from human activities, Zimmerman said. Increased carbon dioxide in the atmosphere stops long-wave radiation from escaping into space, and reflects it back to the earth's surface, warming it, she said.
The impacts go far beyond armadillo migration.
"Any organism that is temperature-sensitive is going to be affected," Zimmerman said.
Areas that once experienced bitterly cold winters, like much of the Midwestern United States, will see new plants, insects and animals slowly invade as the weather warms.
It's already happening. Green tree frogs are following the armadillo north and east across the United States, as are fire ants, MacGregor said.
These impacts were first felt in the Arctic, Zimmerman said.
"We've all seen the pictures of the stranded polar bears," she said. "The Arctic is a window into our future. What you see happening to the Arctic is going to come to the Midwest. It's already started."