MNR predicting above-average winter severity for local deer

Peggy Revell

With data that has been collected so far throughout the district, the Ministry of Natural Resources is predicting an above-average winter severity for the deer population here.
Since 1953, a network of snows stations—located in Atikokan, Rice Bay, and Arbor Vitae—is used to evaluate the winter weather severity for white-tailed deer.
Data is collected weekly, which includes measuring snow depth, the crust condition of the snow using a snow penetration gauge (SPG), and the wind chill using a chillometer.
“Essentially it comes down to both the snow depth and the crusting conditions, [which] work to restrict movement of deer in the wintertime,” noted local MNR biologist Darryl McLeod.
“What that’s going to do is restrict their access to food supplies and it also restricts their abilities to avoid predators, as well,” he said.
“So those are the two key things.”
Temperature is another variable they measure for with windchill since it will affect the deer’s loss of energy just trying to stay warm during the winter months.
“Based on current conditions, we’re above average for this week when we compare it to previous years,” McLeod said of the readings that were taken last Monday before a major snowstorm hit the district.
“But we can take our current readings and make a prediction of what the severity will be at the end of winter,” he added.
“Generally, the end of April is when we’d have our final numbers in,” McLeod noted. “So right now we’re predicting that there’s a greater than 80 percent chance that the winter will be severe for deer at the end of April.”
While above-average winter severity is expected, the MNR is not predicting 2008-09 will surpass any records, McLeod said.
The “most severe” winter the MNR recorded was in 1965-66, he noted, with a record-setting snow depth of 101 cm that was measured one week in March, 1966—the maximum depth they have recorded since starting to collect data in 1953.
“We’re a long ways [from] what we saw in 1965-66, and we’re certainly not as severe as what we saw in the two back-to-back severe winters that we saw in ’95-’96 and then ’96-’97,” he added.
Finalized data at the end of April will give a better picture of the severity of the entire winter, he noted.
“And we’ll use that information to help us decide what we’re going to do with managing the [deer] population for next year in terms of hunting quotas and things like that.”
While winter severity affects all deer, deep snow and cold winters tend to have more of an affect on both adult males and fawns from previous years, McLeod said.
“Males mainly because they go into the winter in poorer condition than the adult females do because of the rutting activity in the fall,” he explained. “So they generally have less fat reserves.
“Fawns, they’re more susceptible especially because of their small body size, and they’re less able to get through the deeper snow than an adult deer.”
Winter severity also has an impact on the pre-birth and post-birth survival of fawns in the spring following that winter, McLeod added.
“So this coming spring, if it turns out the winter [was] severe, there’s likely to be a greater impact on the survival of fawns that are born in the spring of this year.”
Changes in the deer population also mean other species, such as moose, are affected, said McLeod.
With a population that has expanded “considerably” over the last 10-15 years, deer have had an impact on moose through transmitting parasites—particularly brainworm, winter tick, and liver fluke.
“That’s one of the ecological impacts of having expanding deer range or higher deer numbers,” McLeod noted, adding a reduction in the deer population will have the opposite affect on the transmission of parasites to moose.
“Then there’s also the predator/prey cycle, too,” he added. “Wolves, obviously, are highly-dependent on how the deer populations are.”
But while this winter may be severe for deer, McLeod stressed they are an adaptable species that have plenty of ways to cope with the weather.
“They have a bunch of characteristics that help them survive a winter like this,” he noted.
This includes going to “winter concentration areas,” which helps them establish trail networks that allow them to travel around easier and with less energy, as well as serve as a defence mechanism by having a number of deer concentrated in one area.
“They also are able to lower their metabolism, so they can use less energy during the winter months,” McLeod explained. “They have a really good ability to store fat reserves, so that gives them stored energy.
“It’s typical for them to lose a fair bit of body weight through the winter, even in just a normal or average winter.”
McLeod said deer also are really good at seeking out cutting activity in forests where treetops and branches are knocked down, which gives them easy access to food.
“And they also select their bedding areas to help conserve energy, as well, so the thicker stands of conifer, they tend to bed down on sunny south-facing slopes to keep them warmer,” he added.
“So they’re able to do all these things to help them survive even through a severe winter.”