Cougars are on the rise in the Midwest, a place they used to call home. (Photo: Creative Commons: Malcom)

The big cats are back. After a century of decline, cougar populations are re-emerging in parts of the Midwest they used to call home.

"The cougar population declined dramatically from 1900, due to both hunting, and a lack of prey, leaving the remaining population isolated to the American west," said Michelle LaRue from the University of Minnesota, who helped to track the animal's spread by analyzing cougar sightings since the 1990s.

LaRue joined scientists from Southern Illinois University Carbondale and The Cougar Network to look at carcasses, tracks, photos, video, DNA evidence and cases of attacks on livestock across 14 states and provinces of North America, in addition to reported sightings verified by wildlife professionals.

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From this bank of evidence, the team confirmed that there are 178 cougars in the Midwest, with the number of confirmations steadily increasing between 1990 and 2008.

Cougars once lived throughout the U.S., but they haven't been found in Oklahoma, Missouri, or other Midwestern states since the beginning of the 20^th century, according to Scientific American.

"We (now) know there are a heck of a lot more cougars running around the Midwest than in 1990," said Clay Nielsen, a Southern Illinois University wildlife ecologist who co-authored the report while heading the nonprofit Cougar Network's scientific research.

And of the animals confirmed, 62 percent of sightings took place within 12.5 miles of a habitat suitable for cougar populations. The overall population of cougars is currently said to number around 30,000, reports BBC News. And the animals are spreading far and wide, with some found as far south as Texas and as far north as the Canadian provinces of Ontario and Manitoba.

Their expansion across the states has been driven in part by their territorial nature and an instinct to avoid inbreeding or conflict with other cougars.

"When a female cougar has males they have to disperse away from where they were born," LaRue told Scientific American. "As the different pockets of available territory become no longer vacant they have to go elsewhere. That's what we think is happening. There are no more pockets of vacant habitat or territories left in the west. They're forced to go elsewhere, and elsewhere happens to be the Midwest where there's habitat but no competing cougars."

Such cougar dispersal "is what they're programmed to do. Young mammals, even young humans, tend to move away from home," said Paul Beier, a Northern Arizona University conservation biology professor who studies cougars, according to The Houston Chronicle. "They once occupied the midwestern U.S. There's still some appropriate habitat, and this is how they'll find it."

Though these findings, published in the Journal of Wildlife Management, may be heartening for the big cats, they may also present a threat to livestock and humans.

"This evidence helps to confirm that cougars are re-colonizing their historical range and reveals that sightings have increased over the past two decades," LaRue said. "The question now is how the public will respond after living without large carnivores for a century. We believe public awareness campaigns and conservation strategies are required across these states, such as the Mountain Lion response plans already in place in Nebraska and Missouri."