Coyote harassment of dogs is becoming a rite of spring around the Bay Area, but a recent offensive by the yippy predators in San Francisco’s Presidio has caused a neighborhood ruckus and forced the closure of two popular trails to pets.

Coyotes have advanced on, growled at or surrounded dog walkers and their pets four times over the past week, a pattern of aggression that is natural for the wild canines during pupping season, which begins in the spring and continues through the summer, wildlife biologists said Wednesday.

The displays by as many as three coyotes at a time are nevertheless frightening and experts say the activity could escalate into dangerous dog-coyote conflicts if precautions aren’t taken.

The Presidio Trust, which manages 80 percent of the area in partnership with the National Park Service, banned dogs this week on the Park Trail, between West Pacific Avenue and Crissy Field, and the Bay Area Ridge Trail, between Arguello Boulevard and the Rob Hill Campground, in an effort to protect people and their pets.

“They perceive all canines as coyotes, so they are very threatened, very territorial and they are protecting their offspring,” said Michael Boland, chief of parks development and operations at the Presidio Trust. “What’s happening is they are trying to scare the dog away. It’s designed to be threatening, but it can be scary if you are not used to having that kind of interaction with a coyote.”

None of the dogs or their owners was hurt in the incidents, which involved mainly coyotes coming out of brush next to one of the two trails with their hackles up and growling, Boland said. One woman reported being surrounded by three coyotes who advanced on her and her dog until she screamed.

There is a den near the two trails, which Boland said are still safe for pedestrians without dogs because the coyotes do not regard humans as a threat to their pups or territory.

“People feel like they are being attacked, but there is a real difference between a coyote being aggressive toward a dog and a coyote being aggressive toward a person,” he said, adding that people with small dogs often pick them up, creating an even more chilling situation as the coyotes approach.

Coyotes, which are native to San Francisco, recently moved back into the city after being gone for the better part of a century. The first modern sightings were in 2002 in the Presidio and caused anxiety and confusion over how the creatures got there. Answers came in 2004, when Golden Gate Bridge officials viewed video of a coyote dashing across the span from Marin County in the dead of night.

Since then, coyotes have been reported in Golden Gate Park, at the Olympic Club golf course and in several neighborhoods. About 100 coyotes are believed to be roaming the 47-square-mile city.

The Presidio Trust began a comprehensive study of urban coyote behavior and ecology in San Francisco last year in response to rising encounters and stepped-up concerns. Six Presidio coyotes have been trapped and fitted with collars that have built-in radio transmitters and GPS technology. A seventh, the alpha male, is easily identifiable because he has a torn ear.

Researchers have found that there is only one breeding pair and three juveniles from last year’s litter in the Presidio, and they mostly hang around the Presidio golf course, where there are good sight lines. Of the two collared pups that dispersed last year, one was tracked all the way to Woodside before it was hit and killed by a car on Interstate 280. The other one also was killed by a car, Boland said.

“People perceive that we have a lot of coyotes, but in fact, there is a relatively small number,” Boland said. “They are just very mobile and travel long distances.”

Educating the public is important, Boland said, because it is illegal to relocate problem coyotes. Coyotes that become habituated to people — often because somebody fed them — must be killed.

Coyotes are opportunistic and, given a chance, will sometimes kill and eat small dogs and cats, but are not normally aggressive around humans. Although family dogs kill an average of 20 people a year, there has been only one documented case of a coyote killing a human in the United States — the 1981 death of a 3-year-old who was dragged away from her Los Angeles County home.

Experts say most coyotes that have been involved in attacks on humans either have been deliberately fed by people or have habituated to their presence by some other means, like feeding on their garbage or pet food.

Peter Fimrite is a San Francisco Chronicle staff writer. Email: pfimrite@sfchronicle.com Twitter: @pfimrite