Richard Gleeson
Northern News Services

Yellowknife (Jun 19/00) - Next time you're tempted to consider the meaningless of your existence consider the lowly vole.

If it had brain and spare time to think such thoughts, the vole and others of its kind would be completely depressed by them.

Voles, mice, lemmings, shrews and hares of the North live fast and die hard.

In the comparative comfort and safety of a laboratory, for example, deer mice will live from four to eight years. In the NWT, with foxes, hawks, eagles, owls, martens, minks and wolves ready to snap them up at any moment, their average lifespan is one year.

But it's an action-packed year. Deer mice breed two to four times a year. The young they bear breed within five to seven weeks of being born. When they're not breeding, deer mice are either eating leaves and other plant matter, sleeping or avoiding being eaten.

As insignificant as each individual animal may seem, take these prey species out of the ecological picture and everything collapses.

"It's almost like the heartbeat of the ecosystem," said territorial small mammal biologist Suzanne Carrier, referring to the dramatic population swings rodent species go through in four-to-five-year cycles.

There will be 10 times as many deer mice in the NWT when the population peaks compared to the low end of the cycle. The variation in vole and lemming populations is a bit lower at three-to-five times more in peak years than in the low years.

Carrier said there's no mistaking peak lemming years.

"On the tundra you can see so many when their population peaks," she said. "You can't take a step without seeing one."

Or stepping on one.

A measure of the important role rodents and other small mammals, such as hares, play in Northern ecosystems is how closely predator and prey populations are linked.

Trappers look to vole population studies, carried out in the NWT each year, to determine how plentiful marten and other predators will be in the coming seasons.

A year-and-a-half after prey populations peak their predators' numbers peak, since it is the successful breeding of young that would not have survived that drives the dramatic increases.