San Francisco Chronicle Magazine

Sometime in the night our bunkhouse shuddered. Then something roared. I looked out the barred window, which separated the inky night into disjunctive frames. Earlier, eight bears had been milling around outside. Now I was just able to discern their milky forms moving about like Martha Graham dancers on a ghostly set.

I was in Canada, peering out from a mobile lodge on wheels parked 20 miles east of Churchill, Manitoba, on the western shore of Hudson Bay. The tundra buggy bunkhouse shook again, and I heard a familiar howl. Fine. It was the wind (an 100-mile-an-hour wind, I later learned). I gathered my quilt and snuggled in.

The north wind signaled the arrival of winter, when the Hudson Bay waters freeze and polar bears go out on the ice to hunt their most nutritious food, ringed seals. When the ice melts in June or July, the bears come ashore to pass the next four months in "walking hibernation" -- fasting and resting.

It is because of the Hudson Bay bears' unique sea/land life cycle that an interesting event occurs near Churchill every fall. In October, the normally solitary bears gather together -- as many as 1,000 of them -- to await the coastal freeze-up. A fascinating convergence of species takes place as travelers arrive by the thousands to observe.

I was not one of those bear-crazed types. If it hadn't been for my mom, I wouldn't have come. When she'd described "living among the polar bears in the tundra buggy lodge," the thrill in her voice reminded me that Mom rarely closes windows on possibilities. She's always game. I would be, too.

The next morning over wild-blueberry pancakes, I cupped strong coffee in both hands, calculating when to ask the lodge managers if the wind had ever capsized one of these tundra buggy bunkhouses. Before I could speak, Mom whispered, "There's Dancer!"

Yesterday we'd seen the 1,300-pound bear standing 12 feet tall on his hind legs, poking his nose through an open lodge window. Now, in the early light, Dancer was doing polar aerobics, pawing the air, rolling in the snow, stretching his massive neck and anvil head.

Dancer is often the biggest bear around camp. Looking at him up close and remembering what I'd read in biologist Ian Stirling's book "Polar Bears," I felt percolations of wonder. Coating Dancer's massive shoulders and flanks were two layers of insulating fur that kept him warm in temperatures below minus 50 degrees Fahrenheit. Although polar bears appear white, their fur is transparent, each strand a hollow core. When Dancer and the other bears move about, they lumber as if their bones are made of concrete. Part of that slowness is intentional. They are conserving energy, waiting to eat the food that fuels them best, the ringed seal, which has plenty of tasty fat rich with omega-3 fatty acids, something I prefer to get from walnuts. Part of the bears' sluggish behavior comes also from their massive weight, as much as 1,800 pounds for the most formidable males. They have some amazing powers, too. Our guide, wildlife photographer Jenny Ross, marvels at how sea bears navigate home on constantly drifting ice with no landmarks. They had also had a rather accelerated evolution, over 2,000 years, from ancestors that were dramatically different, the brown bear. Dancer's distant cousin is the grizzly.

Watching Dancer stretch, I couldn't wait to get next to him in the roving tundra buggy we used for bear-watching. Most days the sun was stingy, but on this morning it streamed under thick clouds. Our driver, Saskatchewan native Chris Hendrickson, stocked the vehicle with lunch, snacks and warm drinks, then handed one travelmate a broom. "I need to check something from the ground," he said. "If a polar bear gets close, whack him."

A tundra buggy isn't cute like a VW Bug, as its name implies. Instead, it looks like an ice box made for the jolly green giant -- dropped on its side, punched with windows and hoisted eight feet off the ground on giant tires made for farm tractors. On the horizon it resembles a spooky creature from "Star Wars."

Tundra buggies are equipped with propane heaters, double seats and big windows. "No arms or hands hanging out the windows please," Hendrickson warned. Years ago, when an excited photographer rested his elbow on a sill, a bear made a snack of his arm.

Tundra buggy lodges like the one we were staying in are made of individual buggies converted into kitchen, dining and bunk rooms and linked together, Amtrak-style. Bands of windows give constant visual access to the bears. Only two companies have permits to run tundra buggy lodges in the Cape Churchill Wildlife Management Area. Our tour operator, Tundra Buggy Adventures, was the first buggy concessionaire and still had its No. 1 tundra buggy in operation, not for tours but to carry a mounted video camera that streams images to www.polarbearcam.com.

Every day it took awhile to organize our cold-weather gear and camera equipment. We were all amateur photographers, some with professional lenses big enough to spot bruises at a Super Bowl. When the bears moved, the whir-click of camera shutters followed. The only other sounds were our own giggles. Despite being a cliche, the wild white teddies were just too cute.

Jenny Ross, who lives in Truckee, has photographed every bear species in the world. She recently spent two years on assignment capturing photos for her traveling exhibition, "Bears! Icons of the Wild." Ross, a former Harvard-trained attorney who chucked the legal life for a more creative pursuit, didn't conceal her childlike affection for the bears. She said things like, "This magnificent animal is an evolutionary masterpiece," and she talked easily about why some people love the bears so much. "We tend to think they are like us," she said. "They inspire emotion, they're playful, they appear to be affectionate toward one another, and they are good mothers." They also survive by their wits, contemplate challenges, sleep eight hours and break ice in frustration when they miss a meal.

Our group didn't have to travel far from the lodge for action; bears were everywhere. Polar bears congregate near Cape Churchill because ice usually forms there first along the 30-mile coastline extending eastward from the town of Churchill to the cape. While the bears wait for the freeze-up, the 780 Churchill inhabitants adjust their habits. Rule No. 1 is, don't leave town on foot. A "polar-bear promenade" nearby is a death walk for humans. At night, "polar bear police" scare interloping bears with rubber bullets and flares. In the mornings, patrol members ensure children get safely onto school buses, and on Halloween they circulate with the little devils and goblins. Bears have more trouble adjusting. Those addicted to the town dump either end up confined in a holding cell, affectionately called the polar bear jail, or tranquilized and transported away by helicopter.

Remarkably, in recent decades, deaths by bears in Churchill have been few. The last was in 1983. One night a man scavenged meat from the refrigerator of a burned-down hotel, stuffed the food in his pockets, then rounded the corner smack into a bear.

However, close calls continue. Bears normally run from helicopters, but last year one didn't. It hid in a depression, and when a researcher jumped out of the helicopter, the bear knocked her down. Other people were able to scare the animal away. The woman suffered minor injuries.

One night last year two Italians broke down in a rental car. They walked the five miles to town with all senses alert, no doubt appreciating each breath. They saw amazing Northern Lights and made it to bed without trouble.

Inside the buggies I didn't worry; the vehicles were like rolling fortresses. Our only occasional discomfort was the cold. With windows open, I sometimes shivered in my knee-length coat. On the open-air viewing balcony, my nose froze. Mom warmed hers with a thumb-sized fur cap.

Mom also made me put warming packs in my boots and mittens, even though I didn't want them. Soon everyone was wearing them. The days living among the bears were luxuriously timeless. We saw three young adults having a standoff, mothers trailed by twins, bears curled under crusts of snow, bears spread-eagled on their bellies to cool down, two young bears rolling together in a shallow snow pit. We never wanted to move away from any scene.

We spotted almost every activity bear lovers yearn for, including a ritualized sparring between males called play fighting. Why expend the extra energy when they need to conserve it, I asked Ross. She explained that play fighting most likely develops the motor and coordination skills bears need on the ice. Then she added with a mischievous grin, "Scientists try to avoid anthropomorphizing, but the play-fighting polar bears in the western Hudson Bay do seem to be enjoying themselves immensely."

Bears mate in April and May. Instead of returning to ice in the fall, pregnant females enter dens where they typically have two cubs. Newborns weigh less than 1.5 pounds, according to Ross, who once crawled into a den to photograph tiny twins. Mothers nurse them with milk that contains 35 percent fat. When the new families emerge in the summer, the mother hasn't eaten for eight months. Mothers and cubs are fun to watch and hard to spot, but we located several groups.

I was beginning to feel especially small. How physically humble we humans are when stripped of weapons, man-made tools, energy resources and speedy transportation. Around Churchill, our monolithic vehicles gave us tremendous advantages. Looking beyond that, however, I found a new sense of myself as a player of equal, rather than dominant, status in the natural world. Not only the polar bears reminded me of this, but also the three other species that, with the sea bear, make up the subarctic Big Four, including the arctic fox, the arctic hare and the ptarmigan. Also impressive was the complex landscape, rigid with permafrost yet supporting a food chain that began with the lemming and ended with the largest carnivore on Earth. And then there was the climate, which made its stormiest presence known to me that unforgettable bunkhouse night when the north winds bore the promise of winter.

Ironically, the climate may be the bear's final predator. Their ice-bound habitat is disappearing as a result of global warming. Scientific modeling predicts that if the warming trend continues, polar bears may be trying to survive in a nearly ice-free Arctic by the summer of 2080.

Last June, the International Union for the Conservation of Nature announced the Hudson Bay population has declined recently from 1,200 to 1,000. The decline is related to an early break-up and later freeze-up of the ice, the group said. Also this year, the Center for Biological Diversity has asked the U.S. Fish & Wildlife Service to list the polar bear as a threatened species under the Endangered Species Act. It's a sad day when one realizes that for all of the pleasure and knowledge the bears give us, we are poisoning their world in return.

As the tour ended, I admitted the bear cuteness factor was acceptable. I even bought my own National Geographic video. In the Churchill airport, however, I lamented that the Northern Lights, usually easy to see at this latitude, had eluded us. Thirty minutes later, on the Calm Air flight to Winnipeg, we had a surprise: All across the blackened sky ethereal green lights leaped and shimmered in their own boundless dance. I offered my window seat to a woman on the aisle so she could see them. As I stood waiting, head bowed awkwardly under the airplane's low ceiling, I noticed Mom patting her lap. "Sit here, honey," she said. I paused, but only briefly.