No one knows why so many black bears are crossing the road in Sequoia and Kings Canyon National Parks this year, but park officials are alarmed that so many aren't making it to the other side.
So far in 2001, 21 bears have been hit by vehicles in the parks or just outside their boundaries. The latest casualty was a mother bear killed near the Grant Grove entrance to Kings Canyon in mid-September. Its two orphaned cubs were recently captured and relocated by the state Department of Fish and Game.
At least three bears have been found dead on or near roads, but park officials suspect there have been other fatalities among bears that were struck on the roads but died elsewhere. The officials say no motorists have been hurt.
Park officials are perplexed because no more than five bears have been hit by cars in any previous year in Sequoia and Kings Canyon. Unusually dry weather, biologists believe, has caused more bears to forage at lower elevations, near the heavily traveled General's Highway.
But it is not just traffic that is waylaying the bears. It is speeding traffic, park staff members say. Too many visitors are driving too fast on the winding mountain roads of the southern Sierra Nevada.
"It's tacky to hit wildlife, no matter where you are," said David Graber, science advisor at the parks. "But when you visit a national park, it's incumbent upon you to pay enough attention to not damage wildlife or other natural resources. There's no excuse for hitting a bear."
Nevertheless, many drivers have managed to do it.
One bear this summer was hit by a motorcyclist. The bear lived. Another one wasn't so lucky, dying after being dragged an eighth of a mile down a road by a driver who never reported the incident. An abandoned cub was found near the Grant Grove of giant sequoias, leading biologists to suspect its mother was probably hit and then crawled off to a remote den to die.
One of the most upsetting episodes to park staff involved a bear known as Belle. At the age of 1, she was captured as part of a study in 1984, then released. For the last 17 years, Belle led a relatively uneventful life, quietly foraging for food in the park's back country.
But in mid-July, Belle's carcass was found by the side of a road in the Lodgepole area of Sequoia. Her cub was nearby, also dead. Rachel Mazur, a park biologist, thinks the cub was still nursing and refused to abandon its mother. Another bear then wandered along and probably killed the cub.
Again, no driver reported the accident.
"Sometimes a bear will be hurt and will heal very well; some of the bears will go and really suffer and die," said Mazur. "Some of the injured bears become beggar bears and end up hanging out near the road and other developed areas."
The worry, said Mazur, is that Sequoia and Kings Canyon already have their hands full keeping human food from bears. Although bear sightings have dropped at nearby Yosemite National Park, they have inexplicably increased this year at Sequoia and Kings Canyon. Mazur said a small cadre of employees at the park has done a good job holding down bear incidents, but beggar bears remain a chronic problem.
Road kill of wildlife also remains a problem in Yosemite National Park, where 22 bears were hit by cars in 1999 and 2000, with 10 dying.
By contrast, bear deaths on roads in heavily visited Yellowstone National Park, in Wyoming, are low. There, one black bear is killed by a car once every 2 1/2 years, and grizzly bear road mortality averages one every 4 1/2, according to Yellowstone's bear management team. No studies have been done that explain the contrasting numbers.
At Sequoia, "wildlife crossing" signs with a drawing of a bear being trailed by two cubs were posted along park roads in August. Rachel Mazur said she is cautiously hopeful that people will heed them. But she worries about becoming a casualty herself.
"I used to bike to work every day," she said. "But this summer I started driving because it's getting really scary. Drivers have changed."