In March 1998, the U.S. Fish and Wildlife Service released 11 captive-bred Mexican gray wolves into the Apache National Forest, a tract of greenery extending through eastern Arizona. Extinct from the Southwest for the past two decades, the wolves that were reintroduced received the "nonessential experimental" designation under the Endangered Species Act. This label was meant to appease ranchers; it allows them to defend their livestock against the reintroduced wolves. With the label, the reintroduced animals have less federal protection than the wild ones, which cannot be legally harmed. But that creates a practical problem for ranchers, who can't always distinguish reintroduced wolves from wild ones. Now legal action by the ranchers is challenging the effectiveness of the label and could threaten the future of the program.

Conservationists got their first lesson on the legal quandaries created by the labeling from the controversy surrounding another nonessential experimental animal: the reintroduced gray wolves, Canis lupus, of Yellowstone National Park. In the early 1990s the Fish and Wildlife Service trapped wild gray wolves in western Canada and released them in the park. Listed as endangered since 1967, the gray wolf was exterminated from the American Rockies in the early 1900s to quell the fears of ranchers. But populations were allowed to thrive in parts of Canada.

"The gray wolf would've eventually reestablished itself," says Edward E. Bangs, Fish and Wildlife Service coordinator of wolf recovery at Yellowstone. "We knew they were migrating down from Canada into central Idaho and Montana." The service estimates that the northern populations will take 20 to 30 years to migrate into the U.S., whereas the reintroduction program will reestablish the populations in six to seven years.

"But the sooner we get them reestablished," Bangs adds, "the sooner we reap the benefits"--namely, a restoration of the region's precolonial ecological balance. As a result of the reintroduction program, Bangs estimates that between 155 and 170 gray wolves now roam the Rockies; as the dominant predators in the area, they have brought exploding coyote and elk populations under control.

But last December a U.S. district court ruled that the nonessential experimental designation violates the Endangered Species Act because ranchers cannot immediately identify wild wolves from reintroduced ones; they cannot be sure if it's legal to shoot a threatening wolf. So the judge ordered the wolves removed from the park--which in wildlife terms probably means they will be shot.

A similar battle could shape up in the Southwest, where ranchers in New Mexico and Arizona have filed suit to stop the reintroduction of the Mexican wolf, Canis lupus baileyi, a subspecies of the gray wolf. It has been listed as endangered since 1976, and the last confirmed sighting of the wolf in the wild was in 1980, according to David R. Parsons, leader of the Mexican Wolf Recovery Program. The Fish and Wildlife Service looks to maintain captive populations in zoos and to reintroduce these animals into the South over the next five years. Eventually, the conservationists hope to establish a minimum population of 100 wolves, which may take eight to 10 years. Parsons reports that the wolves are adapting well: three family groups were released, and the animals are sticking together, remaining within a three-mile radius of their point of release.

The problem stems from studies that estimate that 100 Mexican wolves will kill up to 34 livestock annually. That has ranchers motivated. Nine organizations, led by the New Mexico Cattle Growers Association, have filed suit to stop the reintroduction. They argue that wild Mexican wolves still roam in the Southwest and that reintroduced captive-born animals might breed with the wild wolves, thus threatening to dilute the genes of the native populations.

Parsons and his group had until late May to defend against the lawsuit. Parsons was not worried. "The situation in the Southwest is very different from the one in Yellowstone," he maintains. Contradicting the ranchers' claims, Parsons argues that "the Mexican wolf is completely extinct in the wild, so there isn't the problem of identifying reintroduced and wild animals. The nonessential experimental population isn't threatened by this lawsuit."

In contrast, the Yellowstone gray wolves face a much more uncertain future. The nonprofit group Defenders of Wildlife has appealed the ruling to remove the wolves, and any action against the animals must await a judgment on the appeals. At the moment, that decision lies in the indefinite future, so the fates of the "nonessential experiments" remain in limbo.