Issue link: http://digital.canadawide.com/i/170490
science M arsha mostly kept to herself. A true west coast native, she lived about 500 kilometres northwest of Vancouver in rugged, steep terrain, amidst trees and shrubs. She was happy to lounge around on occasion and spent other days intently searching for food. Weighing close to 300 kilograms, she was a majestic sight, inspiring awe in those who crossed her path, usually accidentally. Unfazed by what others might see as a formidable nature, Tony Hamilton followed Marsha for five years. "She taught me a lot," says Hamilton, the province of British Columbia's large carnivore expert. A bear researcher for more than 30 years, Hamilton tends to name the bears he follows in the the field. He sits behind his desk in his Victoria office, a big box of hair samples at his feet. A skull rests on a filing cabinet, its toothy grin frozen under a long snout. Marsha? The scientist smiles and shakes his head. "No, a different bear." Hamilton met Marsha in 1984 when he first started studying grizzly bears in the Kimsquit River system. The bear, a teen at the time, led Hamilton along a mysterious journey, from winter slumber to winter slumber. Though bears follow patterns, their behaviour will vary, depending on their environment and whether they are a grizzly, or a black, a female or a male, or a mother. Still, all bears need the same things. Food. Water. Shelter. Space. And whether they live on the coast, in the Interior, in the mountains, or on the plateau, bears move through a yearly five-stage cycle: hibernation, walking hibernation, normal activity, hyperphagia, and fall transition. The following fictionalized account was inspired by Hamilton's study bear, Marsha, and is based on facts provided by him and other bear biologists. The winter dive Marsha's fat. And a little bit pregnant. Sometime after entering her den, a couple of free-floating embryos implanted in her uterus. Mating was a time consuming and exhausting summer exercise— multiple times, multiple males, about 24 minutes for each encounter. But it was also a year rich with berries and salmon. Restoring her energy supplies and putting on the pounds, 80 percent of it fat, was easy. Outside, snow carpets the den. Her home holds her bulk but squeezing through the opening, smaller than the average human doorway, took a ninja move. The tunnel was a tight fit too. But she'll need the security. When the cubs arrive in the next six to eight weeks, they'll be hairless, the size of chipmunks, and voracious sucklers. When bears in B.C. hole up in winter what exactly do they do? It's a matter of semantics, says Øivind Tøien, a University of Alaska Fairbanks researcher who studies black bear hibernation, a term he prefers to "state-of-torpor." Most hibernators, like rodents, bats, and chipmunks, go into a deep torpor, putting the brakes on bodily functions and decreasing body heat so they're close to the ambient temperature, with any temperature variations following a daily rhythm. Bears are different. Tøien implanted radio transmitters into five black bears, tucked them into artificial dens, and spent three winters monitoring their physiology and watching them via video camera—sometimes all night long—to tease out their secrets. Pregnant bears maintain their core temperature at a normal summer level of about 37.5 C. The core temperatures of males and non-pregnant females will drop a few degrees, although rarely dipping below 30 C. Tøien's research also suggests core body temperatures fluctuate on a two- to seven-day cycle, a rhythm not seen in other animals. • wayne lynch left: A hibernating black bear with its three-month-old cub. 22 B r itish C olumbia Magazine • fa ll 2013 opposite: A lean-looking black bear and cubs cross a road north of Fort St. John.