A morning walk in North Park led to a frightening encounter yesterday for a woman and her dog who were confronted by wild coyotes.

Donna Ladow, 65, of Hampton, said she was walking her leashed pet Ty, a chow and spitz crossbreed weighing 60 pounds, near the park's old Wildwood Coal Mine at about 7:15 a.m.

"We went probably 20 to 25 feet off the trail into a field and a coyote came down the hill toward us very aggressively -- no fear of humans whatsoever," said Mrs. Ladow. "Then it called its pack mates -- gave something like a wolf call, it was chilling -- and two other coyotes came down the mountain. There was another one that ran away."

She described the animals as canine, about 15 inches at the shoulder with brown and gray mottled fur.

"They surrounded my dog and me, and I put the dog between my legs," she said. "One was very aggressive and came within 2 feet of me, another was behind me and one to my side. They were getting down low, had their ears back and would charge and circle. I had nothing with me -- it was in the meadow [and] I couldn't get a stick or stone. I screamed. I yelled. They paid no attention."

Mrs. Ladow said she called her husband on her cell phone, then threw the phone at the animals. With Ty still leashed and cowering between her legs, she slowly backed up 10 feet at a time, yelling and waving her arms.

"I had two choices: run and leave the dog there or stay and fight for my dog's life," she said. "It took me 30 to 45 minutes, going 10 feet at a time backwards until I finally got back to the trail. They followed us then until we got around other people. Then they took off."

An avid hiker for 15 years, Mrs. Ladow said she's never encountered wildlife so aggressive and unafraid of humans.

"Sixty-five-year-old women shouldn't have to fight off coyotes in a county park," she said. "The only thing I can think of is, it's breeding time and if one of them had a puppy down in there, maybe we were infringing on their territory."

Representatives of Allegheny County and the Pennsylvania Game Commission said there have been no confirmed sightings of coyotes in North Park, but the animals are common to northern Allegheny, Beaver and Butler counties. And while coyotes are normally reclusive, Mrs. Ladow's descriptions of the animals and their demeanor sound plausible, said Joe Olczak, director of Allegheny County public works.

"That area is near 64 acres of land acquired last year that was adjacent to North Park," he said. "Across the tracks there's a new housing development that just went in, but that valley is pretty remote. Coyotes are very shy, but people could be putting food out for deer or rabbits and they could have lost their fear of humans."

Mr. Olczak said it may have been an isolated incident, but if the Pennsylvania Game Commission were to confirm the presence of unusually aggressive coyotes within the park, bulletins would be posted at the park office warning users. Similar bulletins were posted in 2002 when bears were sighted in North Park.

"We keep encroaching on their habitat and they [could] become used to humans and [pets] being around," he said.

Eastern coyotes are larger than their western cousins. Small populations may have existed in parts of Pennsylvania for millennia, but their arrival in larger numbers corresponds with an expansion from New England into New York and Maryland in the 1940s. Despite rumors of coyotes being stocked by the state, Pennsylvania coyotes carry strong genetic similarities to those that expanded into neighboring states, suggesting a natural expansion and not a controlled release.

Coyotes are opportunistic feeders, eating everything from vegetable matter to litter, carrion, small animals and even white-tail fawns. Unleashed pets, too, can find themselves on the menu. But Mel Schake, Southwest Region information and education supervisor of the Pennsylvania Game Commission, said adult humans, children and larger animals like Mrs. Ladow's Ty, standing 17 inches at the shoulder, are not suitable prey for coyotes. He suspects her instincts about the coyotes' territoriality may be correct.

"I haven't observed the lay of the land there, but about this time of year females are looking for a den site to have their young," he said. "If that's the case, it would not be unusual for two or three coyotes in a group -- a small family unit, adults and young from the previous year -- to protect the den if they thought it was threatened by the presence of a dog."

In a territorial situation, he said, the coyotes' determination to protect the den could override their natural fear of humans.

"It wouldn't surprise me if she wandered into the area of a den site and their aggressive behavior was just really attempting to harass the dog away from the den," he said. "If that's the case, it wasn't an attack. They wouldn't have killed and eaten [the dog], but they'd nip at it and chase it away."

Although Mrs. Ladow was in a frightening emergency situation, Mr. Schake said she responded correctly.

"In that circumstance, I don't know what else she could have done," he said.

The Game Commission's Web site recommends that when confronted by an aggressive wild animal, make noise, throw something at it, wave your arms, don't turn your back, don't stare at it and back up slowly.