BAR HARBOR — Record snows and bitter cold temperatures pose serious survival challenges for the local deer population.
But whether winter has a serious effect on the overall size of the deer herd depends in large part on another factor –spring – according to Maine state wildlife biologist Tom Schaeffer.
“Winter’s a tough time, and even in a mild winter you expect some losses,” Schaeffer told the Islander this week. “But, if they break out of winter in either a normal or an early spring, they do surprisingly well.”
Deep snows certainly make it tough for the deer and cause them to use a lot of extra energy just to move around, Schaeffer said. But the way the creatures have evolved over the years, they typically can withstand extremely difficult winter conditions, from deep snow to icy cold temperatures. The duration of those difficult conditions, however, presents a whole other story.
Deer move into the winter with a limited store of energy and weight. Their metabolism slows significantly over the cold months, Schaeffer said, allowing them to get through the winter season while slowly tapping their energy stores. This balancing act has evolved over thousands of years and allows herds to survive typical winters largely intact and healthy.
Should winter wrap up in a timely fashion, the deer’s stores of energy will last until they can begin foraging for food again. However, should wintry conditions last longer into the spring season, the deer will undoubtedly begin to suffer population losses, Schaeffer said.
“Deer always are losing weight in the winter, it’s just how much they lose. But if they are still losing when they are expecting to be finding food in the spring, that is when problems arise for them,” Schaeffer said. “You’re prolonging the agony now into what might be a normal spring breakup time.”
Does typically carry unborn deer as the spring season unfolds. It is the fawns that suffer the most, Schaeffer said. Because the mothers have so much trouble finding food, unborn deer typically suffer from malnutrition and either will not make it or will be born weak and vulnerable to predators and disease. Conditions where this happens usually cause significant decreases in local deer populations.
Also of great danger to deer as the spring unfolds after a particularly snowy winter are automobiles. As Schaeffer put is, “sometimes once they get on the road where [there’s] good footing underneath, they are awful reluctant to leave.”
During particularly harsh winters in 2008 and 2009, Schaeffer said, mortality from automobile crashes was the biggest cause of losses to the deer population in many areas of the state.
So, even while Mount Desert Island provides much good woodland shelter area for the deer, making it easier for them to get through a harsh winter, this tendency to group in the road could cause significant losses.
Schaeffer speculates that moderating coastal temperatures could allow MDI to get out of winter’s icy grasp earlier than the mainland, possibly giving the deer population here an advantage. Everything hinges, however, on the timing of the spring.
“Even in the best of winters, there’s probably going to be increased losses to deer,” Schaeffer said. “Will it be greater than what we’ve seen for the last 15 years? Probably. Will it be catastrophic or significant? It’s still too early to tell.”