American mountain lions, or cougars²（美洲狮） , are re-emerging in areas of the United States, reversing 100 years of decline. The evidence, published in The Journal of Wildlife Management, raises new conservation questions, such as how humans can live alongside the returning predators³. "The cougar¹ population declined dramatically from 1900, due to both hunting, and a lack of prey⁴, leaving the remaining population isolated⁵ to the American west," said Michelle LaRue from the University of Minnesota. "Here we present the hard evidence that the western population has spread, with cougar populations re-establishing across the Midwest."

Three main cougar populations exist in the Midwest centered around The Black Hills in South Dakota, however, cougars are venturing far outside of this range. One male cougar from the Black Hills was found to have traveled 2,900 kilometers through Minnesota, Wisconsin and New York, before ending up in Connecticut.

"While the distance the Connecticut cougar traveled was rare, we found that cougars are roaming（漫步，闲逛） long distances and are moving back into portions of their historical range across the Midwest ", said LaRue. "Our study took in over 3,200,000 km² of territory, confirming the presence of Cougars from Texas, Arkansas and Nebraska, to the Canadian provinces of Ontario and Manitoba."

Working alongside scientists from Southern Illinois University Carbondale and The Cougar Network, LaRue and Principal Investigator⁶ Dr. Clay Nielsen analyzed⁷ cougar sightings which have been reported since the 1990's to characterize confirmed sightings over time, assess habitat suitability and confirm where cougar populations are being re-established.

Aside from confirmed sightings, the team’s evidence included carcasses, tracks, photos, video, DNA⁸ evidence and cases of attacks on livestock⁹ across 14 states and provinces of North America. Only sightings which were verified by wildlife professionals were included, while sightings of animals known to be released from captivity¹⁰ were excluded（排除） to ensure only natural repopulation was analyzed.

The results reveal 178 cougar confirmations¹¹ in the Midwest with the number of confirmations steadily¹² increasing between 1990 and 2008. Approximately 62% of confirmed sightings took place within 20km of habitat that would be considered suitable for cougar populations.

When cougar carcasses were recovered 76% were found to be male. As the Connecticut example shows, males are capable of traveling long distances and this finding suggests males are leading a stepping-stone dispersal（分散，传播） of the cougar population.

"This evidence helps to confirm that cougars are re-colonizing their historical range and reveals that sightings have increased over the past two decades," concluded LaRue. "The question now is how the public will respond after living without large carnivores for a century. We believe public awareness¹³ campaigns and conservation strategies are required across these states, such as the Mountain Lion response plans already in place in Nebraska and Missouri."