Nov. 10, 1995
Current logging practices should be altered to be more compatible with the housing needs of B.C.'s black bears, says a Simon Fraser University graduate student.
Helen Davis, an SFU master's student in biological sciences, has spent the last three years in the woods of northern Vancouver Island studying the effects of logging on the denning needs of coastal black bears.
In the fall, every black bear seeks out a winter shelter, or den, in which it hibernates until spring. Coastal black bears den in or under hollow trees, stumps, and fallen logs.
"Finding the right den can be the difference between life and death for a bear," explains Davis. "Not only does the bear have to be kept sheltered for several months, but it also has to be hidden from predators, such as wolves and other bears."
Davis's thesis work, partially funded by Canadian Forest Products Ltd., was part of a larger research project on the habitat ecology of black bears in the Nimpkish Valley. The study area is actively logged, and has large tracts of old second-growth forest.
Davis trekked throughout the 20,000-hectare study region, locating and describing bear dens, and taking a detailed inventory of the vegetation and landscape. She also 'consulted' directly with the local ursine population, capturing bears and attaching radio collars, following them around until they denned, and returning in the spring to examine their dens once they'd left.
In the end, Davis confirmed previous suspicions that the bears do indeed rely on old-growth structures for dens. Worse yet, these structures are all decaying, with no hope of replacement under current forest practices.
"Dens are, on average, about 140 cm in diameter, yet second-growth trees on an 80-100-year rotation will only reach about 80 cm in diameter," she says. "So once the old- growth structures in these second-growth forests have decayed, what are the bears going to use?"
Davis describes her study as the first step toward guidelines for maintaining denning supply for bears, which may be enforceable under the new Forest Practices Code.
"The logging industry is being very positive about this," she reports. "In the past, they've cut into trees with bears in them; they've even cut through bears. But now, they want to know the right thing to do when they find a den, and what to do if there's a bear in it. Many times they can just move the cut block boundary."
Another bear problem - possibly linked to logging - may not be as easy to solve, adds Davis, who has submitted a paper on the disturbingly high degree of cannibalism she saw among the bears. "We had five cases in one year, the highest anyone has ever seen anywhere," she says. "We think it might have something to do with the spatial relationship of clearcuts, and the way bears are concentrating in them to feed, but more study needs to be done."
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