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The Brothers Wild

GRIZZLIES CAN WEIGH UP TO 1,000 POUNDS, RUN AS FAST AS A HORSE, crush a moose's skull with one powerful blow and, after biting a 700-pound rival's thigh, shake him, in the words of the Craigheads, as a "terrier shakes a rat." The bears' tread may be silent, their mood unpredictable and their bite powerful enough to puncture thick metal. These are hardly typical attributes of an underdog, yet in 1959, when Frank and John began their new project, that is precisely what the humpbacked bears were. With their massive bulk and menace, grizzlies, who are the very image of wild America, were considered at best nuisances and at worst threats to human life. In the lower 48 states, they were vanishing.

How much trouble the bears were in, no one really knew. What was known, the Craigheads wrote at the time, was that "the usual 'communication' between man and grizzly is through a rifle bullet." With funding from several sources, including the National Geographic Society and the National Science Foundation, the Craigheads began what the society called "Operation Grizzly Bear" in Yellowstone and surrounding forest areas. It was the largest grizzly population in the country outside of Alaska, but one that was under increasing pressure from human use. The study was meant, they wrote, "to rendezvous with grizzlies in their most intimate moments." The twins started off trying to answer the basics: How many grizzlies were part of the Yellowstone ecosystem? What did they eat? How long did they live, and what were they dying from? When did they mate? What was the size of a typical home range? Were there seasonal patterns to their movements? What was the social structure of grizzly society? Where and how did they den in winter? What were their reproductive rates?

The brothers wanted to document every detail of grizzly bear life, and to help them along the way, they almost always had a handful of graduate students -- many of whom went on to become highly regarded carnivore experts themselves. The twins started their first year by capturing 30 grizzlies (in drop-door metal traps) -- immobilizing them and taking as much data as they could before affixing plastic ID tags in the bears' ears. The next year would bring another 37, and by the end the brothers figured that upwards of 600 grizzly bears had been part of the study. Within a year of starting, they wrote, "Now we can write the terms for a badly needed grizzly life-insurance policy." What they were beginning to find out gave backbone to a management program that could help save the grizzly from extinction.

But they could have used a little insurance themselves, given all the hazards.

They had to make their way through snow sometimes 20 feet deep, over "jackstraw piles of wind-felled trees" and along miles of rough terrain in extreme weather. In order not to lose a bear they were following, they might not sleep, except for a few catnaps, for 40 hours straight; continue hiking in sweltering heat for 24 hours after their canteens ran out; or strip naked to ford the waist-high water of an icy stream at night, leaving their extremities so numb that they would stumble for the next quarter-mile of the hike.

They were always on guard not to "jump," or startle, a shortsighted bear. And the twins, masters of the one-arm pull-up, according to the family, insisted that any students on the project work on their calisthenics so they could get up a tree -- fast -- if need be. Sometimes as a prank, the brothers claimed that a bear was coming just to drive home the point.

By 1966, the Craigheads would report, "Time and again we have been treed by bears." Once, as Frank stood in the semi-darkness, he was suddenly aware of seven grizzlies running shoulder to shoulder directly at him "like an onrushing train." Fortunately, grizzly bears generally want to avoid human contact, and, at the last second, as the bears caught his scent, they veered away. Often enough, the Craigheads would have to race into a stream to prevent a bear they'd shot with a tranquilizer dart from drowning -- unsure, even as they plunged in, whether the animal was still awake enough to attack. One time, a mother bear tracked them in their truck to get her cub back. And on another adventure, they were backed out onto a high, snowy cliff ledge with nowhere to go by a black bear they thought had been knocked out with a dart. It was a relief when the bear, wanting to simply get away from the human intruders, scaled a vertical snow wall to escape them.

But the Craigheads shrugged off the notion that what they did was dangerous. They were proud of the fact that they never had to use their guns defensively, though 15 bears -- primarily in the first years of the study -- died during immobilization as the twins perfected their ability to estimate dosages. While admitting that dealing with a drugged and unpredictable grizzly was like "working over dynamite with a damp fuse," their attitude was to find humor in the face of danger. "When releasing grizzlies," Frank wrote dryly, "point them away from you."

A Yellowstone Park ranger asked the brothers if they were worried that the bears -- who could still feel, hear, see, and smell while drugged -- might recognize them and come after them at a later date. Frank replied: "Bob, we've got that all worked out. Each time we handle a grizzly, we slip into ranger jackets and put on ranger hats."

THE BROTHERS GOT TO KNOW SEVERAL BEARS VERY WELL -- and named them -- Pegleg, Shorty, Loverboy, Scarface and Beep. And they always wrote with compassion about the animals' struggles in life and, often enough, their deaths. Female grizzly No. 75 died after being darted, though the twins tried reviving her with artificial respiration. John wrote in his entry for September 28, 1963: "We had great respect for No. 75 as she was the epitome of grizzly nature . . . she was one of the fiercest and most aggressive bears we have encountered . . . She had attacked us on several occasions. We all felt depressed at losing this old friend." They were fonder still of Bear No. 40, better known to the Craigheads and to their National Geographic readers as "Marian." Once, after the brothers had startled her, she merely glared at them tolerantly, when a more aggressive bear would have charged. The Craigheads realized that all the time they were learning about her, she was taking their measure as well. "A relationship of trust, and perhaps respect, was developing," Frank wrote. Through her, the twin scientists would learn much about grizzlies -- such as the fact that females are not sexually mature until the age of about 4 1/2. They learned through her actions that grizzlies prepare their winter dens well in advance of their actual slumber. And, through many of her social interactions, they came to better understand bear hierarchies; for example, females with young -- by sheer force of necessity -- often ramp up their own aggressiveness and advance their place in the pecking order. Marian was a bear with a personality. Born in 1958, she was prolific in grizzly terms -- having seven cubs in seven years. Watching her, especially with her cubs, made the bear world seem closer to their own.

"Out in the meadow Marian was half sitting, half lying on her back, in much the same attitude as a rocking chair that a slight push would topple backwards," Frank wrote in his book Track of the Grizzly. "It was the mother bear's nursing position, and the two large cubs were sucking vigorously and roughly." The babies made a buzzing sound -- like that of bees around a hive -- that expressed their contentment. And when Marian wanted them to stop, she rolled the cubs over in an invitation to play. It was with Marian, on September 21, 1961, that the Craigheads made a technological breakthrough that would change the speed, depth and breadth of their work -- and that of countless other field biologists. That was the day they placed a radio collar around Marian's neck. For the first time out in the field, scientists could reliably find and follow a big, elusive carnivore using telemetry. In his book on grizzlies, nature writer Thomas McNamee would say this event would "make possible the first penetration of human light through the ancient opacity of bearhood."

OVER THE COURSE OF 12 YEARS, the Craigheads discovered that the grizzlies were not loners, as was previously believed, but maintained elaborate social hierarchies. They observed that females will adopt orphaned cubs and that the bears were slow reproducers. The twins were able to follow bears to their dens for the first time -- discovering when bears head for their winter sleep (it's triggered by certain snowy weather conditions), and where and how they construct their living quarters (facing north, usually at the base of trees or stumps, usually outfitted with conifer boughs as snug beds). The bears always made their own dens and never reused them. Home ranges varied widely for individual bears, the brothers learned. All bears were artful scavengers and had favorite seasonal food sites (most often including a park dump). The Craigheads found it was true that you could slice a grizzly's premolar and determine age as you would a tree, by counting the rings. Their bears sometimes lived to be 25 or 30, but the average lifespan was more like 5 or 6 years. The researchers listed all the ways grizzly bears died -- battle wounds, old age, malnutrition, even gored by bison -- but noted that humans were usually the cause.

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