Thursday, February 03, 2005

Illinois Armadillos?

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We’ve grown accustomed to the alarms raised when a new species of animal makes its way into Illinois, and in most cases with good reason. Creatures like the Asian longhorned beetle and the Bighead carp wreak havoc on ecosystems and threaten our economy. But there’s a newcomer to the southern part of our state that seems to be stirring up more curiosity than eradication plans--the nine-banded armadillo.

Nine-banded armadillos are the most numerous and widely distributed of the twenty species of armadillos that exist today, and the only kind that inhabit the United States. They are native to South and Central America, but they’ve been expanding their range for at least the past hundred and fifty years. They were first reported north of the Rio Grande in Texas in 1849 and have steadily spread north and east from there. During the early part of the twentieth century, another population of armadillos was established in Florida when they were brought there by people and released. That population also spread rapidly and converged with the Texas population in northern Florida and southern Georgia in the 1970s. Armadillos now also occupy parts of South Carolina, much of Alabama, Mississippi, Oklahoma, southern Kansas, Arkansas, western Tennessee, and southern Missouri. Individuals have even been reported as far north as Nebraska.

Will Illinois be added to the list of states that armadillos call home? People have reported seeing them here since the 1970s, but a flurry of sightings in recent years has prompted Joyce Hofmann and colleagues at the Illinois Natural History Survey to look into the issue.

With support from the Illinois Wildlife Preservation fund, they surveyed 135 people familiar with the animal life of southern Illinois and solicited reports of armadillo sightings by birderwatchers. Respondents reported 76 different armadillo records from 22 counties between 1999 and 2003, mostly in the western half of southern Illinois. There were also reports in 2004 from seven additional counties.

How armadillos arrive in Illinois is an open question. They might be brought by people and released, as they were in Florida. Or they might come as stowaways in cargo on barges, trains, or trucks. Or they might arrive on their own power walking across bridges, or--unlikely though it may be--even somehow crossing the Mississippi river.

Although we know that armadillos can get to Illinois, we don’t yet know whether or how well they might become established here. Cold will eventually stop their spread north, since they can’t hibernate and depend for food on insects and other creatures they find by digging in the earth. Where the ground stays frozen for too many days in a row during winter they are unable to dig for food and can’t survive. The current prediction for their northern limit is a line that runs across the state about a third of the way up from the bottom.

Whether or not armadillos become Illinois residents, they are fascinating for their many quirks.

When they are startled, armadillos may jump four feet into the air, and they are surprisingly fast for such ungainly looking creatures.

Armadillos don’t float naturally, so they cross small bodies of water by walking across the bottom, like divers wearing weights. When they must swim, they can make themselves buoyant by gulping air to partially inflate their intestines.

Armadillos typically give birth to identical quadruplets every year, and they can delay pregnancy at the earliest stages to ensure that young will not be born until weather conditions are favorable.

And of course, armadillos are the only North American mammals that grow their own armor.

If you happen to see an armadillo in Illinois, make a note of the date and location and contact the Illinois Natural History Survey. You’ll be contributing detail to a unique ecological success story.