By LESLIE KAUFMAN

Cathy Hayes was telling jokes as she recorded a close encounter with a buffalo on her camera in a recent visit to Yellowstone National Park. “Watch Donald get gored,” she said as her companion hustled toward a one-ton beast for a closer shot with his own camera.

Seconds later, as if on cue, the buffalo lowered its head and charged, injuring, as it turns out, Ms. Hayes. Because she was using her zoom lens, she misjudged how far away the animal was.

The history of the national parks in the United States is full of examples of misguided visitors feeding bears, putting children on buffaloes for photos and dipping into scalding geysers despite signs warning of scalding temperatures. As an ever more wired and interconnected public visits parks in rising numbers, rangers say that technology often figures in mishaps, as it has for some time.

A French teenager was injured this summer after plunging 23 meters from the South Rim of the Grand Canyon when he backed up while taking pictures. And last autumn, a group of hikers in the canyon called in rescue helicopters three times by pressing the emergency button on their satellite location device.

When rangers arrived the second time, the hikers explained that their water supply “tasted salty.” The National Park Service does not keep track of what percentage of its search and rescue missions are technology related. But the service recently felt compelled to add “inattention to surroundings” to more old-fashioned accident causes like “darkness” and “animals.” The service acknowledges that the new technologies have benefits as well. They can and do save lives when calls come from people who really are in trouble.

But in an era when most people experience the wild mostly through television shows that push the boundaries , rangers say visitors can wildly miscalculate the risks of their antics. In an extreme instance in April, two young men from Las Vegas were killed in Zion National Park in Utah while trying to float a hand-built log raft down the Virgin River.

A park investigation found that the men “did not have whitewater rafting experience, and had limited camping experience, little food and no overnight gear.” Far more common , park workers say, are visitors who arrive with cellphones or GPS devices and little else and find themselves in trouble.

“We have seen people who have solely relied on GPS technology but were not using common sense or maps and compasses, and it leads them astray,” said Kyle Patterson, a spokesman for Rocky Mountain National Park, just outside Denver. Like many national parks, Rocky Mountain does not allow cellphone towers, so service that visitors may take for granted is spotty at best. “Sometimes when they call 911, it goes to a communications center in Nebraska or Wyoming,”

Mr. Patterson said. “And that can take a long time to sort out.” One of the most frustrating new technologies for the parks to deal with, rangers say, are the SPOT personal satellite messaging devices that send an emergency signal but are not capable of two-way communication.

In some cases, said Keith Lober, the ranger in charge of search and rescue at Yosemite National Park in California, the calls “come from people who don’t need the 911 service, but they take the SPOT and at the first sign of trouble, they hit the panic button.” But without two-way communication, the rangers cannot evaluate the seriousness of the call, so they go to the expense of responding as if it were an emergency. Helicopter trips into the Grand Canyon National Park can cost $3,400 an hour.

“Because of having that electronic device, people have an expectation that they can do something stupid and be rescued,” said Jackie Skaggs, spokeswoman for Grand Teton National Park in Wyoming. “Every once in a while we get a call from someone who has gone to the top of a peak, the weather has turned and they are confused about how to get down and they want someone to personally escort them,” Ms. Skaggs said. “The answer is that you are up there for the night.