A biologist examines a 5-inch by 5-inch wolf track near the south boundary of Crater Lake National Park, Ore., while on the trail of a gray wolf known as OR-7. (Richard Cockle / The Oregonian / December 16, 2011)

The arrival in California of the lone wolf OR7 serves as both a marker of one of the great successes of the Endangered Species Act and a reminder of how much California has changed since wolves last roamed within its borders, more than 80 years ago.

It's been easy to cheer from afar the wolf's return from extinction in the lower 48 states. But OR7's border crossing from southern Oregon on Thursday puts Californians on notice that one day, the reintroduced gray wolf population is expected to at least partly reestablish itself in the state. OR7 might not be the one — he might move back and forth between states or permanently rejoin his pack in Oregon, and in any case, he doesn't appear to have a mate. But wildlife biologists are certain that other wolves will venture into the state. Unfortunately, they have not yet planned how to deal with their arrival.

California is one of the most environmentally progressive states in the nation. It is also home to 10 times as many humans as when wolves last were present, which means far more opportunity for clashes between the two species. Antipathy to the wolves in other Western states led to a disturbing act of Congress in 2011 to override the Endangered Species Act and undermine the wolves' recovery by delisting them in Idaho and Montana, states that are more sparsely populated. The two states promptly approved hunting of the wolves, which has already thinned the numbers of the Northern Rockies group by at least 150 (after it had reached 1,651 in 2010). It remains to be seen how the Great Lakes states will contend with their wolves, which now number more than 4,000; the U.S. Fish and Wildlife Service is delisting that group, an action that is expected to take effect this month.

Assuming that Congress doesn't pass any more laws to countermand science, the wolves would be protected in California. But ranchers here dread their return; the wolves almost certainly will threaten at least some cattle, as they have elsewhere, though they mostly hunt wildlife. California should consider following Oregon's lead, by creating a fund to compensate ranchers for any losses while encouraging nonlethal ways of discouraging wolves from preying on livestock.

It would be nice to think the wolf could simply return to its role as a wild predator that helps preserve the balance of nature — the reduction of deer and elk populations, for example, has helped restore waterways in other Western states. But much has changed in California's wild spaces in the past 80 years. With the number of invasive species throughout the state, natural balance has become a rare thing. And it's too much to expect that the human-wolf relationship will ever be easy. What we can realistically hope for is that the wolf will reach healthy, self-sustaining numbers, and resume a place in the life of this state.