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By Chris Marchand
One step to either side of the well-trodden path to the MNR’s snow study site is evidence enough of winter’s challenges on local wildlife. Even with my weight distributed on six square feet of snowshoes, I’m left post-holing through nearly a metre of snow, punching through nearly to the ground.
It’s been an interesting winter for the Dryden area, one that has shown only the slightest signs of loosening its grip. It’s years like this in particular when an MNR program, which has been quietly gathering data for over 60 years can give provincial biologists a useful tool for evaluating winter severity on wildlife.
How do you quantify something like ‘severity’?
Once a week, MNR Forest Management Technician Mike Durocher faithfully straps on his snowshoes and with clipboard in hand heads out onto the MNR’s snow course, located in the vicinity of Aaron Park to record data for SNOW 4.0 (Snow Network for Ontario Wildlife), one of 40 stations across the province.
At the ‘chillometer’ station, an old pressure cooker has been hooked up to electricity which maintains water at a temperature of around 40 degrees celcius, close to the internal body temperature of a mammal. Exposed to the wind and the ambient temperatures, biologists use electrical meter readings from the chillometer to extrapolate the calorie requirements of animals like deer or moose to maintain their core temperature under winter conditions.
Durocher takes readings from a set of ten snow-depth meters along a trail under the forest canopy. At each station he drops a spring-loaded telescoping pole (not unlike a pogo stick) into the snowpack, pushing it down to the ground measuring the amount of force needed to penetrate the snow.
“This information (chillometer) compiled with the observations from the measurement sticks and the compaction tool — those three numbers put together formulate a final result to determine the severity index. Between the wind and the temperature, how cold is it on the animal? How much snow are they dealing with? How does it affect them when they put their hoof into the snow?”
The winter of 2012-13 has crossed the threshold of what biologists call ‘severe’ in wildlife terms. While snow depths are high, though short of records, the data indicates that animals are enduring a deeper, softer snowpack later than normal.
“If you look at the (snow depth) graphs of past years, in a lot of them you see that it tops out in the last few weeks and then starts a downward plunge,” said Durocher. “At the same time this year it’s still ramping upwards. This is the time when animals are depleting all of their reserves, all the fat they stored up to sustain themselves through the winter. They almost seem like they drop into first gear, trying not to expend energy.”
Snow compaction is another game changer in a Northwestern Ontario Spring that seems to be lagging behind the historical data. A firm crust favours deer moving away from their winter yarding areas in search of new food sources, but it also works to the advantage of predators or can damage the legs of deer and moose leading to infection.
Dryden MNR Biologist Lisa Eddy says winter conditions in 2012-13 will play a natural role in helping to control the deer population. The energy requirement on the animals will make it more difficult for offspring to thrive.
“We’ve had other severe winters in the past five years, just not with the same dynamics as this year,” said Eddy. “We don’t really consider winter feeding in this area, particularly because our (deer) population up here in Northwestern Ontario is controlled by severe winters, it’s a natural cycle. The population fluctuates so much that a feeding program wouldn’t have any long-term impact. Over the past few years a lot of communities have had concerns about deer populations within the municipalities — so those two things are in conflict with each other.”