In a conservation breakthrough for one of Northern America’s most romanticized creatures, a pack of wolves is roaming free in California for the first time in nearly 100 years.

On Thursday, the California Department of Fish and Wildlife announced that a pair of adult gray wolves and five pups have been discovered in southeastern Siskiyou County — a revelation that has environmentalists cheering and some ranchers deeply concerned.

All but eradicated from the lower 48 states of America by the early 20th century, wolves have staged a major comeback over the past 20 years after U.S. wildlife officials re-established the animals in Wyoming and Idaho. The predators made their way to Oregon by 1999 and have now made their home in the northern reaches of California.

“This is an Endangered Species Act success story in the making,” said Pamela Flick of Defenders of Wildlife, a conservation nonprofit.

The return of the wolf is more than a symbolic achievement, environmentalists say. The pack hunters make ecosystems healthier by killing sick or weak animals and keeping the populations of deer and other prey in check.

Fish and Wildlife captured photos of the wolf family — dubbed the Shasta Pack for its proximity to Mount Shasta — on Aug. 9. The department had planted surveillance cameras in the forested region after spotting an adult wolf in May and July.

All the wolves in the pack are black in color, which is fairly common among gray wolves, according to Karen Kovacs, the agency’s wildlife program manager for Northern California. The pups are estimated to be about 4 months old and weigh between 35 and 40 pounds.

Fish and Wildlife has been preparing for the arrival of a pack since 2011, when a wolf designated OR7 crossed into California from Oregon. That wolf, which returned to Oregon in 2013, was the first detected in California since 1924.

But the appearance of the Shasta Pack came sooner than Fish and Wildlife had anticipated.

“These animals have a tremendous ability to reoccupy former range (and) their reproductive potential is quite high,” Kovacs said Thursday. “These are very resilient critters.”

Kovacs and wildlife experts emphasized that wolves pose little threat to public safety. But the re-establishment of wolves in California could threaten the livelihoods of ranchers who raise cattle and other livestock.

“The possibility of wolf-livestock interaction is a big concern for us,” said Kirk Wilbur, government relations director for the California Cattlemen’s Association, which represents about 1,700 ranchers across the state.

Gray wolves are protected in California under state and federal endangered species laws. Killing or even harassing the animals is prohibited. Wilbur said ranchers would like to have the ability to drive off and, as a last resort, kill any wolves that threaten their livestock.

Fish and Wildlife expects to release a draft of a wolf management plan by the end of the year. The agency has discussed the possibility of reimbursing ranchers for animals that are killed by wolves.

But that’s not the optimal approach, said Wilbur, noting that it can be difficult to prove how a livestock animal was killed. Sometimes the carcass is never recovered. Other times it’s picked clean by scavengers.

“They would like to protect their livestock in the first place,” Wilbur said of his members, “rather than have their livestock brutally taken down by a gray wolf and then get compensation for it.”

There is no evidence at this point that the wolf pack has taken any livestock, and ranchers who own land in the Shasta Pack’s territory have not expressed animosity toward the predators, Fish and Wildlife officials said.

The agency plans to reach out to hunters — some of whom worry that wolves could deplete deer and elk populations — about the presence of wolves and how to distinguish them from coyotes, which may be shot.

As of 2014, there were 1,657 wolves in Montana, Idaho and Wyoming and 145 in Oregon and Washington, according to the U.S. Fish and Wildlife Service. Officials presume the adults of the Shasta Pack are descended from Oregon wolves but are not the offspring of OR7.

To enable wolves to thrive in California, an array of stakeholders — including animal advocates, hunters, ranchers and government agencies — will need to find common ground, said Defenders of Wildlife’s Flick.

“We’ve really been given a second chance to restore this iconic species to the landscape that they’ve been missing from for nearly a century,” she said. “And we really must seize this opportunity to forge new partnerships to let wolves live in harmony with people and livestock.”

Contact Aaron Kinney at 650-348-4357. Follow him at Twitter.com/kinneytimes.