Big cats on the prowl: mountain lions, once pushed to the edge of the U.S. frontier, have been growing in numbers and are moving eastward. Watch your pets. (science times).

When Greg McCoy found Oreo, his daughter's house cat, in the jaws of a mountain lion last year, he grabbed the big cat by the tail with both hands, dragged it onto his front lawn, and jumped on top of it.

With his left arm, he tried to hold the writhing lion in a headlock. With his right hand, he attempted to yank Oreo from the lion's mouth.

As McCoy, who is 37 and 215 pounds, tugged on the bloodied house cat, the lion--an adult female weighing perhaps 100 pounds--struggled out of his headlock. Before it ran off to eat Oreo, it swatted McCoy across the face with a rear paw.

"It felt like a fist with four nails in it and it brought me to my senses and I decided I better let go," says McCoy, who lives in the mountains on the outskirts of Boulder, Colorado. "I had read about how to deal with a mountain lion, but none of that entered my head when I saw one with my daughter's cat. I was plain mad stupid."

He was also lucky. The lion left four scratches on his right cheek, which have since healed without scars. Wildlife experts say that swat could easily have torn off much of his face.

MAKING A COMEBACK

These are vexing times for Western suburbanites and the big cats that increasingly skulk among them.

The mountain lion, an ambush predator that was long trapped and poisoned as a varmint, has been resurgent since the 1960s when many western states categorized it as big game, with limited hunting seasons. No one knows how many there are, but a recent estimate by wildlife ecologists put the number at over 31,000 in 12 western states.

There may now be more mountain lions in the West than there were before European settlement, says Maurice Hornocker, a senior scientist at the Wildlife Conservation Society.

"For more than 100 years we kept them away from human development by killing them whenever they showed up," he says. "That isn't the case anymore, and so they are taking advantage of it."

The human population in states with mountain lions is also surging with newcomers attracted by the rugged outdoors. This mix has coincided with an increase of attacks on people, which now average about four a year, up from one a year before 1970. Since 1890, mountain lions have killed 17 people, 11 of them children, in the United States and Canada. More than half of these deaths occurred in the past 12 years.

Now evidence is growing that mountain lions, the world's fourth-largest cat, are moving east, pushed by their own breeding success and pulled by an abundance of deer, their favorite meal, to the far side of the Mississippi.

FINDING NEW GROUND

A car killed a young male recently near Kansas City, Missouri. It was the first confirmed sighting of a free-roaming mountain lion in the region in more than 100 years. Scientists have also confirmed the presence of seven mountain lions in northern Michigan, where the animals were supposedly wiped out 95 years ago.

The cats appear to be exploring east across the Great Plains, with confirmed sightings or roadside carcasses in Nebraska, Kansas, North Dakota, Iowa, and Minnesota. Within the past decade, a thriving population has established itself in the Black Hills of South Dakota. Young male mountain lions have been observed traveling 400 miles to establish new territory.

Depending on where they live, mountain lions and their subspecies are also called cougars, pumas, panthers, and catamounts.

"They will eventually get to New Jersey," or at least close, says Paul Beier, a wildlife ecologist.

HUMAN PREY

Scientists have revised their understanding of big-cat behavior since the 1990s, when the rate of human deaths began to rise. Once thought to hunt only at dawn or dusk, the cats began to attack suburban deer in midafternoon. Supposedly averse to humans, a threat only to solitary children, they began to stalk adults and even groups.

Experts advise that if people encounter mountain lions they should face them directly, try to appear large, shout and make noise and back away from the animal.

"With deer available in the East and young cougars heading in that direction, there is going to be an increase in human conflicts," says Tina Ruth, a wildlife expert.

Boulder, a town of 96,000 people in the foothills of the Rockies, is open both geographically and as a matter of policy to wildlife that chooses to wander into town. While rangers carry rubber buckshot to ward off big cats, many residents refuse to report lions because they do not want to get the animals in trouble.

Consider the experience of the mountain lion that ate Oreo and swatted Greg McCoy. Rangers in Boulder will destroy a lion that harms people, but McCoy did not report the incident. "We choose to live in their backyard," he says, "so we got to put up with them."

With no one to chase her off, that lion continued to hang out in the neighborhood. Two days after wrestling McCoy, it killed a mule deer behind a house across the street.

Emily Hiller, 9, spotted the visitor through a window, dining on bloody flesh in the backyard while she was eating toast with peanut butter in the kitchen. "Oh, it's a mountain lion, mom!" she shouted.

Emily's parents rushed to the window, took pictures, and invited neighbors over for a look. McCoy's daughter, Kristina, 9, who is Emily's best friend and whose cat had been killed by the new backyard attraction, was among the visitors. She said she forgave the big cat for eating Oreo.