by Joe D. Shorthouse
Professor Emeritus, Laurentian University, Sudbury
MANITOULIN—Rain on snow events in mid-winter are always a source of concern for residents of Manitoulin Island, livestock, wildlife and the environment. The storm during the night of Thursday, February 7 was particularly harsh as it turned the entire Island into a giant skating rink and hillsides that looked like luge runs at an Olympic site.
The storm resulted in one cm of ice forming on the surface of about 100 cm of snow from Manitoulin to Sudbury where we began our perilous trip to Mindemoya at around noon the next day. Like everyone on Manitoulin, getting out of our Sudbury driveway and onto roads that had yet to receive sand or salt was a major challenge. Our plan was to visit Manitoulin to photograph the ice fishing derby and winter sports.
Thankfully, the roads from Sudbury to Manitoulin were mostly ice-free but one dare not step out of your car in a parking lot once onto the Island without taking extreme caution. We waited until noon on Saturday to visit Lake Manitou and Manitowaning Bay to watch the fishers, but if it was not for tracks made by snowmobiles, we could not have walked onto the lakes.
Over the two days we drove from Mindemoya to Manitowaning, Providence Bay, Gore Bay and Kagawong, venturing down side roads where we were amazed that our Grand Caravan remained firmly on track. However, it was an eerie feeling seeing fields free of footprints and realizing that deer were unable to walk on the surface without breaking through the ice crust and damaging their legs.
There were no signs of deer along the boardwalk at Providence Bay and few footprints at the sites we usually see deer in Gore Bay.
As reported in the February 6 issue of The Expositor, deer on Manitoulin were already in trouble this winter before the rain event. Deer Save has been calling on volunteers to cut trails around feeding grounds with snowmobiles, but with the ice storm, the need for more trails and compacted deer yards with feed is even more important.
Unfortunately, the layer of ice will have an impact on more than deer, cattle and people. Small mammals such as voles and mice that remain active throughout the winter under the snow will have their lives altered.
Shrews, voles and mice live in a space under the snow where the temperature remains near 0°C throughout the winter, there is abundant food, and they are protected to some degree from predators. This space is called the subnivean environment and small mammals, insects and spiders are able to move about in relative comfort regardless of the temperature above the snow.
Oxygen and carbon dioxide freely passes through the snowpack but with the formation of an ice layer, an exchange of gases will be impeded, to the peril of subnivean animals. Plants that continue to photosynthesize in the subnivean environment throughout the winter will also suffer from the ice barrier.
Mice and voles often tunnel to the surface to disperse to new feeding sites, but will be unable to penetrate the ice layer. This in turn has implications for foxes and owls that feed on mice and voles.
The high insulative nature of snow is also used by grouse that dive into the snow pack on cold nights making a kind of quinzhee (a shelter made by digging a cavity in a mound of settled snow). Grouse will not be able to penetrate ice one cm thick and will likely be severely damaged when they attempt to do so.
Rain on snow events have occurred on Manitoulin Island in the past; however, the event on February 7 appeared to be more severe, widespread and damaging than usual.
A 2015 report on the impact of climate change on the Great Lakes Basin, prepared by the Ontario Climate Consortium and Ontario Ministry of Natural Resources and Forestry, predicted an increased intensity of winter rain and snow. Hopefully future rain events in the winter will be accompanied by warmer temperatures and thick layers of ice as we just witnessed will be avoided.