When the Yellowstone grizzly bear was listed as threatened under the Endangered Species Act in 1975, there were only about 100 to 200 of them in the park and the surrounding country.
The main culprit in their decline was, oddly, garbage. Bears raiding dumpsters in a campground or, say, lapping up bacon grease behind an outfitter’s tent were often shot as scary nuisances.
A 35-year campaign to clean up dumps and bear-proof garbage cans – and to teach people to keep picnic baskets and coolers in the car – has had a significant payoff. There were 717 grizzlies at last count in the 20 million acres in and around Yellowstone National Park.
Still, the bears have all but disappeared from almost all of the continental United States, except for Yellowstone and Glacier National Parks and a few other slivers of habitat. All told, there are about 1,800 in the lower 48 states. One reason for the overall decline is that they have the lowest reproductive rate of any mammal in North America, besides humans.
Sows have their first cubs at 5 to 8 years of age, and space them three years apart. Just 1 in 3 cubs survives to adulthood. A grizzly lives about 30 years on average.
Now scientists are at a crossroads: Some biologists say that the grizzlies’ numbers are robust and that it is time to remove the most stringent protections for the bears, “delisting” them under the species act, which among other consequences means they would probably be hunted again for sport. That prospect disturbs even those in favor of lifting the restrictions.
Citing the grizzly’s recovery in the wild country in and around Yellowstone, the Fish and Wildlife Service tried to delist the bear in 2007. Environmentalists sued, and a federal court forced officials to redo an analysis of the future of the whitebark pine tree, whose nuts are an important food for the bears.
The tree’s numbers have declined widely as the climate in the Rocky Mountains has warmed, and tree-killing insects are taking a steep toll.
Nevertheless, federal biologists say the plan to manage the grizzly after delisting is adequate. But lifting protections is still a hotly contested proposition.
If delisting is completed this time – perhaps as soon as the end of the year – park officials will continue to manage the bear within Yellowstone’s 2.2 million acres, where they will essentially remain protected.
But in the rugged, wild country around the park, the Fish and Wildlife Service would turn over management of the bears to the states of Montana, Idaho and Wyoming. That would probably mean a return to the hunting of grizzlies for sport in those states.
Kerry Gunther, a biologist who heads the bear management program at Yellowstone, says he favors delisting the bear. But although he is a hunter, Gunther says he cannot imagine shooting a grizzly. “Each bear is an individual,” he said. “They are highly intelligent.”
But sympathy for the grizzlies is often accompanied by fear. The big bears – males range up to 700 pounds and females up to 400 – occasionally attack humans; last year, a hiker in Yellowstone was killed by a sow with two cubs.
There would be a limit on total grizzly deaths a year in the Yellowstone ecosystem, which would include everything from hunting to bears hit by a car or dispatched by biologists. If numbers drop below 600 in the ecosystem, “discretionary mortalities” will be halted, including hunting.
Critics say that delisting would put the big bears at risk and that it is being done for political, not scientific, reasons. Many Westerners vehemently oppose the federal authority represented by the Endangered Species Act; some ranchers say bears are preying on their herds more frequently, and some hunters are eager for a trophy.
But the grizzly population is lower than federal officials believe and is dwindling, according to David Mattson, a retired wildlife biologist who has analyzed federal data. The delisting proposal has also given short shrift to the effects of warmer and drier weather, he added. The ecosystem is “unraveling” because of climate change, he said, and will continue to do so as temperatures rise.
The decline of key bear foods, like trout, pine nuts and elk, means the population may continue to drop, Mattson said.
“Why rush with a decision to delist, when all indicators are of a population that is vulnerable and positioned to decline even more than they already have?” he said.
Other researchers argue that the grizzlies are likely to prove resilient to climate change. Studies show that the bears are wide-ranging omnivores, eating everything from ladybugs and moths to earthworms, plant roots, grass and wild berries.
If they lose one food source, Gunther said, they will switch to another. “Bears are better adapted to deal with climate change than a lot of other species,” he said. “They once ranged from Alaska to the arid regions of Mexico.”
Scientists like Gunther also argue that a great deal has been learned about grizzlies, now one of the most studied wildlife populations.
Whatever the future holds, the recovery of the Yellowstone grizzly has been remarkable. While cleaning up garbage has been central, there were other important elements: Domestic sheep have been moved out of bear habitat, and homeowners were urged to keep dog food and bird seed out of the reach of bears.
Technology has also played a key role. About 10 percent of the region’s grizzlies were fitted with GPS collars by federal biologists in the 1990s. Whereabouts of some bears now is recorded every hour and beamed to an airplane to be downloaded onto researchers’ computers.
The result is a very detailed picture of what a bear has been foraging, where it is traveling – and the habitat that needs to be protected.
Sophisticated hair analysis has opened another window into how grizzlies live. Snagged on barbed wire traps, the tufts provide clues to the bears’ diet.
“In each hair is all of the isotopes of what he’s been eating over the last six months in chronological order,” said Chris Servheen, the director of the Grizzly Bear Recovery Program at the Fish and Wildlife Service.
DNA in the hair also provides a detailed picture of the population – individual sex, families and migration – without ever touching a bear. All of this powerful science assures the grizzlies’ future, said Servheen, who is leading the delisting effort.
Perhaps the most important factor in the bears’ recovery in the Yellowstone region has been changing attitudes. Many once saw the grizzly solely as a nuisance or threat; today, it is more common to find respect, and an acceptance of the fact that Yellowstone is one place where humans are not at the top of the food chain.
“The ESA does work if it’s applied properly,” said Servheen, referring to the Endangered Species Act. “If we can recover grizzly bears, we can recover lots of things.”