With beads of sweat running down her face on a steamy late-summer morning, Peggy Callahan cups hands to mouth and produces a low, long guttural wolf howl.

Suddenly more than a dozen captive wolves at Callahan’s Wildlife Science Center near Forest Lake — home to some of the animals since they were pups — join the chorus, tipping their heads skyward and producing a hair-raising cacophony.

Twenty seconds later they are silent.

Callahan, 51, clad in a dirty tank top and shorts, with knees muddied from working in animal pens, smiles. She is clearly in her element — outdoors, knee-deep in wolves, black bears, mountain lions and other critters that are studied and displayed at her center. This day, 20 senior citizens are visiting, and Callahan — her hands animated as she speaks — explains wolf reproduction, habits and management.

“Wolves kill other wolves — for food, breeding, status,’’ she tells the group near a pen with rare Mexican gray wolves. “That’s the unromantic picture.’’ Her words flow like water from a tap, and she barely pauses to catch a breath. Despite the sweltering heat, she has their rapt attention.

Callahan, who grew up in Rochester, Minn., is founder and executive director of the center, which has 60 captive wolves, including gray wolves, red wolves and Mexican gray wolves, as well as five black bears, two Wyoming mountain lions, a couple of bobcats and more.

But this is no zoo.

The center is a combination research and education facility. The captive animals are used for research, and wildlife students, biologists and researchers come from around the nation to learn firsthand about them — knowledge used to study and manage wild populations. And 20,000 citizens, ranging from preschoolers to seniors, come yearly for the center’s educational programs.

The wolves are the No. 1 attraction. Some have been raised by humans since they were born. All are habituated to Callahan and her staff, which allows them to go inside wolf pens to clean them, and treat the wolves or take samples from them. None will ever be released into the wild, so the habituation reduces the stress on the wolves when they must be worked with by Callahan and her staff.

But the wolves aren’t tame, Callahan notes. There’s always the chance one will challenge Callahan’s dominance — just as wolves challenge each other in the wild. “We have one wolf that I raised since it was pup, and it clearly would love to kill me,’’ Callahan said. “I have to go into that pen with several other people for safety.’’

Callahan has been enamored of wolves since she was a kid. “I had a German shepherd, and I told everyone it was a wolf,’’ she said. At age 8, she wrote to famed Minnesota wolf researcher Dave Mech.

“I told him I wanted to study wolves and was worried there wouldn’t be any. He wrote back and said there will be wolves around for you to study.’’

She stayed on the science course, got a biology degree from Carleton College and in 1985 began working for the Wolf Project, a federal wolf research facility located where her center is now. She managed the captive wolves there and helped refine the use of anesthetics to immobilize wolves during research. She helped with field studies of black bears, red fox, deer and wolves and was involved with capturing wolves at Isle Royale.

But federal funding for the project ended in 1991, and the 40 captive wolves housed there were going to be euthanized. Callahan decided to try to keep the facility open as a nonprofit.

“I quit grad school and got a job as a zookeeper at the Minnesota Zoo,’’ Callahan said, while continuing to work at the Wolf Project facility. “It took two more years for us to raise enough money for me to leave the zoo and work here full time.’’

The nonprofit Wildlife Science Center, operated on state land, opened to the public in 1994, and melds research with education. “I love the idea that these captive animals get used for more than just display,’’ Callahan said.

For example, nine federal Wildlife Services employees recently learned to anesthetize and draw blood from the center’s mountain lions. “I feel if you have captive animals, you use them to the fullest extent, obviously without being cruel,’’ she said.

Researchers have used the center’s wolves to try to develop nonlethal ways of keeping wild wolves away from livestock, with flags and loud noises. State researchers have used the center’s black bears in food-preference research. Mech himself is involved in wolf-coyote hybrid studies at the center. And the red wolves are part of the federal government’s captive breeding program.

Wolves, of course, are a lightning rod for controversy, and Callahan and her center haven’t avoided the occasional strike. Last year, Callahan wrote a commentary published in the Star Tribune supporting the controversial new wolf hunting-trapping season.

“Some people love wolves so much that the thought of one dying is not simply distasteful, it is abhorrent, unbearable,’’ she wrote. “The wolf is no longer a predator that has recovered its population — the wolf represents something beyond an animal to many.’’

When she opened the center, she wanted to tell the story of wolves from a science perspective. “In the end the science of wolves is far more exciting than the myth of this animal,’’ she said. “Wolves are phenomenally more interesting as a predator, and not as a demigod.’’

Ultimately, Callahan said, hunting won’t determine the future of Minnesota’s wolves.

“The issue that faces wolves is human sprawl,’’ she said. “This is a land issue, not a hunting issue.’’

Meanwhile, Callahan hopes visitors to her center will take away a better understanding of wolves. “I want them to appreciate wolves. I don’t want them to lose perspective of what they are.’’