The grizzly bear, symbol of the vanishing American wilds, is disappearing at an alarming rate from one of his last two habitats in the lower 48 states.

Fewer than 200 of the giant, ferocious beasts remain in the Montana and Wyoming backwoods around Yellowstone National Park, and the number of adult females may have dropped to as low as 30, according to a long-term study. Recent estimates had said there were between 300 and 400 grizzlies in Yellowstone, and a total of about 1,000 in the lower 48 states.

The bad news was compiled in an urgent-sounding memorandum by the Interagency Grizzly Bear Study Team, a state-federal group that has been monitoring the grizzly population for almost a decade and seeking ways to save the bear.

"Unless some change occurs, the probability of retaining this wildland species in Yellowstone National Park is minimal," said the Aug. 17 memo from Roland Wauer, a National Park Service official. The bear's other remaining habitat in the lower 48 states centers on Glacier National Park and the Bob Marshall wilderness in Montana, where the bear population is not as threatened. The bears are still found in large numbers in Alaska.

Hunters and poachers in the Yellowstone area are killing the wild bears illegally, in violation of the Endangered Species Act, and profiteers are selling their claws as "macho" charms to be worn around the neck, the memo says. (The claws are said to sell for up to $250 each.) The memo says the bears are also threatened by civilization -- such as vacation-home developments, which have gobbled up the grizzlies' old prowling grounds.

"Grizzly bear habitat is being nickle-and-dimed out of existence," the memo says. It warns that planned energy development near Yellowstone, including geothermal, oil and gas development now under consideration by the Interior Department, could further erode the bears' habitat.

A number of warnings have been sounded over the past 25 years about the possible disappearance of the grizzly, a creature of awesome size and strength (adult males weigh as much as 1,000 pounds) that once ruled the wilderness from Mexico to Canada.

The bears numbered about 50,000 in the Colonial period, according to the memo. While several state and federal officials questioned the latest estimate, they generally agree that the bear's numbers are shrinking.

Government agencies and wildlife enthusiasts consider it essential to save the bear, in part because it symbolizes the nation's early history.

The grizzly is "a reference point of whence we came as a culture," said Tom Hobbs, chief ranger of Yellowstone. "Once they're gone, they're gone forever."

"He's one of the few animals in the North American continent that just scares the hell out of the average person," said Dick Randall, a Rock Springs, Wyo., nature photographer who works for Defenders of Wildlife. "I think it's wonderful to have something roaming around this earth that man hasn't mastered, a creature we not only respect and love, but we're afraid of."

The memo calls for stiffening the civil penalties for killing grizzlies and for expanding the investigative arm of Interior's Fish and Wildlife Service. It also calls for continued studies of the bear's population and of the effect of "human activity" on them.

Ranchers have shot grizzlies in the Yellowstone area to protect their sheep and cattle, according to a criminal investigator for the Fish and Wildlife Service there. Although these killings are technically illegal, it is difficult to persuade federal or state prosecutors to bring charges, he said.

And spokesmen in the Yellowstone region said the budget for investigating grizzly-related crimes, now a top priority, is expected to be cut sharply next year.

Ron Tipton of The Wilderness Society, who obtained the memo and made it public, called it "a powerful argument for passage of the National Park Protection Act," a proposal to give the National Park Service the authority to stop development outside of parks that threatens their resources and wildlife.

The Interior Department opposes the measure, calling it an unnecessary expansion of federal power.

The grizzlies have dwindled with the advance of civilization. Unlike the coyote, which has adapted to human neighbors, the grizzly is a blustery beast that roams as much as 100 miles a day, with little regard for man or machine.

A National Park Service spokesmen said the agency could not respond to the memo until its director, who is out of town, returns later in the week.