Cold weather has an upside, if you’re a grey wolf or whitefish
Frigid temperatures were a boon to an endangered population of grey wolves and helped kill the invasive emerald ash borer, researchers say

Toronto Star
By Kate Allen
January 30, 2014

Frigid Torontonians cheered the return of slightly less terrible weather Thursday. But January’s dispiriting cold had an ecological upside, and some people — lovers of a beleaguered wolf population, haters of an invasive pest and anyone who likes whitefish — were deeply appreciative of the deep freeze and perhaps even hopeful for more.

For just the third time in 15 years, an ice bridge has formed linking Isle Royale in Lake Superior to the mainland near Thunder Bay.

Isle Royale is home to a threatened grey wolf population: eight wolves remained at last count and they are deeply inbred, so their pups have trouble surviving. The last addition to the island gene pool, a male nicknamed Old Grey Guy, arrived from the stable mainland population by ice bridge in 1997.

“This is a huge opportunity,” said Carolyn Peterson, logistics coordinator for a long-running experiment tracking the wolf and moose populations on Isle Royale. “We’re just hoping. It would be marvellous.”

Ice bridges used to form in three out of every four winters in the 1950s and 1960s, Peterson added; the population then hovered between 20 and 30 wolves.

Of course, the ice bridge is a risk as well as an opportunity. The Isle Royale wolves “could decide to go to Thunder Bay and take in a movie and maybe mate with somebody” and never return, Peterson said. When an ice bridge last formed, in 2008, two wolves went missing permanently.

Still, scientists have their hopes up that wolves will come rather than go: it could be one of the last chances for new individuals to augment the native population naturally, since research has predicted that by 2040 no ice bridges will reach the island at all.

The deep freeze was not so advantageous for the emerald ash borer. That is good news: the invasive Asian beetle has already wiped out millions of trees across Ontario, Quebec and the United States.

Insect species native to Canada have a variety of strategies for surviving the cold. One of those is “supercooling,” when an insect produces compounds called cryoprotectants that work exactly like a car’s antifreeze and lower the body’s freezing point.

The emerald ash borer can supercool too, but only up to about -30 C, said Barry Lyons, a research scientist with the Canadian Forestry Service.

Unfortunately, since the temperatures in Toronto never dipped lower than -24 C, and borers burrow into tree bark where it’s slightly warmer, there likely won’t be much of an effect on the pest here.

“But up here in Sault Ste Marie, where we also have emerald ash borer, the temperatures might have dipped low enough to affect some of the population,” said Lyons.

“We’re probably getting some mortality, but not a total population collapse.”

The frozen Great Lakes, meanwhile, benefit more than just wolves. This week, ice coverage reached 60 per cent, a level not seen this early in winter since 1994.

The freeze could be a boon to some fish populations, such as whitefish, that spawn in fall and winter — if there is a stable ice cover, it protects the fish from storms and predators.

It could also help water levels in the Great Lakes come spring and reduce shore erosion, though both of those processes are complicated by other factors.

Ice coverage on the Great Lakes in February and March could be reduced if a storm blows in and breaks some of it up, said Denis Dubé, senior ice forecaster at Environment Canada.

But “if it were to stay cold, we could certainly challenge the maximum,” he said. That was in 1979, when 94 per cent of the lakes were frozen over.

Beyond the cold, this winter’s heavy snow has also been a plus for moose. White-tailed deer have co-evolved with a brain worm; the parasites don’t harm the deer, but have a seriously damaging effect when they “jump ship” to moose, says Dennis Murray, a biologist at Trent University.

As winters and springs have warmed, the deer and moose have mingled more in the critical season when deer are shedding these parasites. “It’s had a pretty dramatic negative effect on moose populations.”

But this winter’s deep snow drifts will limit deer mobility and confine them to agricultural spaces away from the forested habitats that moose prefer.

Likewise, “it’s going to be a good year for amphibians,” says Murray. Frogs and other amphibians breed in seasonal spring ponds that dry up by summer, and more snow means more ponds.

The cold and snow have one more environmental upside, said Franz Hartmann, executive director of the Toronto Environmental Alliance.

“If it sparks conversations among people about why we are seeing these extremes, that’s only a good thing,” Hartmann said. “Hopefully that will get people to start realizing, well guess what? Climate change is here.”