The official small mammal of Texas is becoming a Yankee. Blame global warming. Or maybe just wanderlust Texans feel proprietary about the armored mammal, but we hardly have a monopoly on its range. It's not even a native. The nine-banded armadillo, the most prolific of the 20 species of armadillo and the only one to live in the United States, crossed the Rio Grande about 150 years ago. In recent years, though, it has been spotted as far north as Illinois. "I don't know exactly how they get here," said Joyce Hofmann, a research scientist with the Illinois Natural History...