As a full moon settled behind the hills west of Alston Park earlier this week, the haunting howl of a coyote echoed across the 157-acre, open-space park.

Coyote sightings have become the talk of the open-space park in northwest Napa.

Red Rock Cafe owner Dan Menzel said he first spotted a coyote at the park about two months ago.

"I as walking with Sam (his 16-year-old cattle dog mix) when he went tearing after one. It went into the shrubs along a fence, then chased Sam back out," he said.

His dog returned and, he said, "The coyote started coming toward me ... then just stood there looking at me, maybe 60 feet away."

About a week-and-a-half ago Menzel spotted a pair of coyotes while walking his other dog, a 4-year-old German Shepard named Diva. "She started barking like crazy. There were two (coyotes) on the other side of the fence. They just stood there while she was barking, then walked along the fence line and back into a vineyard," he recalled.

Amateur photographer Vicki Isborn said she's seen the wild animals on three recent occasions. One time, a coyote was sitting on a rock pile above a vineyard reservoir just south of the park. "It just turned around and walked into a vineyard," she said. "Its rear leg appeared injured."

She said her 26-pound fox terrier started to trot in the direction of the coyote but when she called, Spider returned. "I don't think either one saw (the) other," she said. "I was relieved."

Trudy Brutsche, a board member of Napa Humane, also has had three sightings in the past two weeks. "I'm sure it was a coyote," she said. "I know what coyotes look like."

She said a friend with two very small corgi dogs had a close encounter. The dogs ran toward a coyote, which ran away, but suddenly turned around and ran toward the dogs. It stopped short, however, when the human was spotted. "I'm sure they were in danger," Brutsche said.

"I'm so delighted Alston Park is still undeveloped, so we have the opportunity to see wildlife, even though it is in the city," Brutsche added.

"They are everywhere," California Department of Fish and Game wildlife biologist Allan Buckmann confirmed. "Coyotes are one of the most ubiquitous species."

He said there is no official coyote count locally.

"It's the time of year that food starts getting scarce, and they spend more time following their prey ... coming closer to people," he said. "They usually hunt possums, jackrabbits, raccoons, skunks and rodents, but have been known to attack cats and other small domestic animals."

Buckmann warned people against leaving pet food outside. But it is more difficult, he said, to keep the carnivores away from livestock feed.

"Humans provide more feed (for coyotes) than is normal," he said. "We've actually stimulated their population growth."

He said coyotes have gotten along well with humans, and have some positive benefits. "By knocking down their predators ... they can stimulate the bird population," he said.

They also reduce the numbers of pesky rodents.

Buckmann said coyotes tend to travel in packs, but on occasion are spotted alone. "The dominant pack member usually does the killing," he said.

If spotted, they will want to keep their distance. People should also leave them alone. Although it's rare, "they can be aggressive -- sometimes too aggressive," he said.

Coyotes in Napa County generally grow to about 35 or 40 pounds, but Buckmann said he once spotted one in Calistoga that he estimated to be 70 pounds.

They look like dogs, with pointed snouts and busy tails that extend parallel to the ground.

Coyotes, members of the dog family, are found throughout North America and have adapted to changes caused by human encroachment over the past 200 years.

Their howling is a way of communicating with other coyotes. They also "yelp" when playing -- particularly pups. A coyote bark is made if threatened. To call pups without making a lot of noise, they often "huff."

Biologists say coyotes are one of the most adaptable animals in the world, capable of changing their breeding habits, diet and social dynamics, according to an article in DesertUSA.com, a monthly Internet-based magazine.

"They play an important part in the ecosystem and are not just wild dogs," Buckmann said. "And they are everywhere."