Anyone who has ever spotted a grizzly bear ambling amid the natural grandeur of Yellowstone National Park has witnessed a living tribute to the power of the federal Endangered Species Act.

The grizzly, protected by the federal law for more than 30 years, has bounced back from fewer than 150 to the point where today there are an estimated 600 in and around Yellowstone, and a total of perhaps 1,400 in the lower 48 states.

Indeed, the grizzly -- Ursus arctos horribilis, a subspecies of the brown bear -- has recovered so well that the U.S. Fish and Wildlife Service is removing those in the western park's vicinity from the endangered list. Other groups of these magnificent animals in Montana, Idaho and Washington will remain protected.

This development might be welcome news in the world of conservation if the Bush administration could be trusted to be a careful steward of wildlife. The strong suspicion that it cannot is only confirmed by news that the Department of the Interior is mulling over ways to weaken the Endangered Species Act, passed by Congress in 1973.

Work to "update" the law reportedly is being undertaken at the behest of Interior Secretary Dirk Kempthorne, who unsuccessfully tried to water down the law in 1998 when he was in the U.S. Senate. The key this time is that the changes, which may include reducing protection for wildlife habitat and turning some authority over certain species to the states, would not require approval by Congress.

Circumventing the legislative process would be a bad idea even if the law really needed to be amended, but there is no real evidence that political appointees inside the Interior Department want to do anything more than abandon its protections in favor of increased man-made development in wild areas.

The Endangered Species Act has served admirably to protect not only the grizzly but the bald eagle, manatee, condor and Florida panther -- in all, some 1,400 creatures that otherwise would disappear forever from the natural environment.

Now that they've been given a chance to thrive, neither the grizzly nor its similarly endangered cousins should face a new threat from ideologues.