February 27, 2008
Study identifies potential cougar habitats
CARBONDALE, Ill. — Don't try to sell Clay Nielsen on the idea that a breeding population of cougars has taken up residence in Southern Illinois. Despite the occasional reported sighting, the science just doesn't back it up, and science is where Nielsen puts his faith.
But some recent research by Nielsen and a graduate student at Southern Illinois University Carbondale does show the cougar might continue moving back toward the Midwest, where only about a century ago it thrived in the tall grass of the undisturbed prairie and thick cover of the forest.
Nielsen's two-year study looked at potential cougar habitat in nine Midwest states: Arkansas, Missouri, Minnesota, North Dakota, Oklahoma, South Dakota, Nebraska, Kansas and Iowa. Since 1990, researchers with the non-profit Cougar Network have confirmed more than 150 cougar presences throughout this region, he said.
The researchers did not include Illinois or any state east of the Mississippi River because cougar confirmations there are almost non-existent, said Nielsen, an assistant scientist with the Cooperative Wildlife Research Laboratory at SIUC. Only two such confirmations were in Illinois — one in 2000 in Chester and one in 2004 in Mercer County — and Nielsen was involved in investigating both.
"Sightings don't count," said Nielsen, who previously did a project that looked at cougar confirmations in the Midwest. "We're using hard science, and that involves real proof, like a cougar carcass, DNA or a photo where you can make a positive identification."
What Nielsen's research does reveal, however, are several large areas in the Midwest that offer ideal habitat for the tan, carnivorous cats, which typically weigh in between 100 and 150 pounds and can grow as large as 200 pounds.
It turns out that Arkansas, Missouri and Minnesota have substantial areas that could attract and support cougars. About 19 percent of Arkansas, for instance, is highly suitable, with 16 percent of Missouri and 11 percent of Minnesota.
"One of the first questions we have about cougars in the Midwest is where is the potential habitat," Nielsen said. "Cougars, like bobcats and wolves, are very adaptable, and juvenile males are capable of dispersing from western populations to the Midwest."
The Shared Earth Foundation, along with the Summerlee Foundation and the wildlife laboratory, funded the research, which Nielsen and former SIUC graduate student Michelle LaRue, of Hudson, Wis., will publish this year in the science journal Ecological Modelling.
LaRue and Nielsen conducted the project in a somewhat unusual way for a wildlife research project. Instead of heading out into the wilderness, the project involved surveying nationally known cougar experts for their opinions on what makes ideal cougar habit and then mating those responses with geographic computer modeling using layered data sets from the National Land Cover Database.
Nielsen and LaRue asked experts to rank how important each of several criteria is in the big cat's habitat. Such factors included distance to water and the density of human population, among others. Of the 20 they sent out, 11 experts returned the surveys.
Then the pair used computers to overlay satellite imagery and databases cataloging land cover, road density, human population density, distance to water and topography. By combining the existing geographic conditions with the expert's rankings, they identified areas with the most potential habitat in units of 90 square meters.
"Ideally, if there were lots of cougars around, we'd put radio collars on them, determine their locations on the landscape and the cougars themselves would be informing us about critical habitat," Nielsen said. "However, there aren't many cougars present in the Midwest. So when the animals can't inform us as to what's important, the experts will.
"We also overlaid the model with cougar confirmation locations — where their presence was determined by carcass or photographic evidence — to see if our model made sense, and it did," he said. "We observed that cougar confirmations existed in areas of good habitat as predicted by our model. Most cougar confirmations occurred in forested areas with low human influence and rugged topography. Most folks who know anything about large carnivore biology would know that the corn desert is not the best place for cougars and wooded areas with steep topography are going to be good for wild animals that like secretive areas and require some cover year-round."
While the study points to the potential for cougars to live in certain Midwest regions, Nielsen says it's important to note that the existence of ideal habitat does not mean those areas are currently playing host to breeding cougar populations.
"This is a first look only," Nielsen said. "This is the first large-scale model of potential habitat for cougars in the Midwest. It is not current cougar distribution in the region."
Overall, about 8 percent of the Midwest offers highly favorable habitat for cougars. In general, more forest cover and rugged terrain is good habitat for cougars, Nielsen said, while areas with high human influence, row-crop agriculture and lots of roads are inhospitable.
The study identified six large, contiguous areas of highly favorable habit that are equal to or greater than 2,500 square kilometers in size. Those areas include northeastern Minnesota; Mark Twain National Forest in Missouri; Ozark National Forest in Arkansas; and Ouachita National Forest in Arkansas and Oklahoma. It also includes Badlands, N.D., and Black Hills, S.D., where there are known breeding populations of cougars, Nielsen said.
The study also identified much smaller areas of highly suitable land scattered throughout the nine-state region. Nielsen said such oases might act as "stepping stones" for animals dispersing from west to east. These areas tend to run along major rivers, and Nielsen said it is well known that cougars use river corridors to travel.
Although parts of Southern Illinois might have some characteristics that are favorable to cougars, Nielsen said there are also important differences. The Shawnee National Forest, while large by some standards, may not be large enough to support a cougar population. "Compared to the Ozarks or the Black Hills, the Shawnee is drop in the bucket, considerably smaller and not nearly as contiguous," he said. "It is pretty wild, but not nearly so as some of the places we assessed in our habitat model."
The Shawnee also is a long way from the next nearest population of cougars in west Texas, Nielsen said. And despite some confirmed sightings there, there's no guarantee a breeding population of cougars will even make it as far as the Ozarks.
Nielsen said he hopes the study will enable other researchers to further study cougar distribution and dispersal trends.
"Someday we may have cougars in these potential habitats, but it's going to take a lot of movement west to east for that to happen," he said. "If we have increased cougar dispersal in the future, and if that will happen, we don't know. This study depicts potential habitat for these animals. Most dispersers are juvenile males, and it will require more females to travel into the Midwest for any breeding populations to eventually occur."
Caption:
Face to face – Clay Nielsen, an assistant scientist in the Cooperative Wildlife Research Laboratory at Southern Illinois University Carbondale, holds the skull of a cougar killed by a hunter in 2004 in Mercer County, Ill. Up until 100 years ago, cougars roamed the plains of the Midwest. A new study by Nielsen and former SIUC graduate student Michelle LaRue has identified areas within nine Midwestern states where the big cats might find good habitat if they ever make it back. The two-year study looked at potential cougar habitat in nine Midwest states: Arkansas, Missouri, Minnesota, North Dakota, Oklahoma, South Dakota, Nebraska, Kansas and Iowa. Since 1990, researchers have confirmed more than 150 cougar presences throughout this region. The SIUC study found Arkansas, Missouri and Minnesota have substantial areas that could attract and support cougars.
Jeff Garner photo
Face to face – Clay Nielsen, an assistant scientist in the Cooperative Wildlife Research Laboratory at Southern Illinois University Carbondale, gazes at the skull of a cougar killed by a hunter in 2004 in Mercer County, Ill. Up until 100 years ago, cougars roamed the plains of the Midwest. A new study by Nielsen and former SIUC graduate student Michelle LaRue has identified areas within nine Midwestern states where the big cats might find good habitat if they ever make it back. The two-year study looked at potential cougar habitat in nine Midwest states: Arkansas, Missouri, Minnesota, North Dakota, Oklahoma, South Dakota, Nebraska, Kansas and Iowa. Since 1990, researchers have confirmed more than 150 cougar presences throughout this region. The SIUC study found Arkansas, Missouri and Minnesota have substantial areas that could attract and support cougars.
Jeff Garner photo