Little vole holds key to the forest

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This article was published 22/08/2003 (8326 days ago), so information in it may no longer be current.

HOLDING a small steel trap tightly in her left hand, Monica Reid pulls back its main spring with the middle and index fingers of her right hand.

She then uses a looped string to secure the “snap trap” — which is baited with a mixture of peanut butter, bacon fat, rolled oats and chopped nuts — to a marker on the pine-needle-littered boreal forest floor.

Reid has set 600 such traps within a two-kilometre radius of the Taiga Biological Station — located 250 kilometres northeast of Winnipeg in what used to be part of Atikaki Provincial Park — in the expectation of catching a red-backed vole.

This mouse-sized mammal — prey for foxes, weasels, owls and other animals — is the backbone of the vertebrate food chain in the largely unknown boreal forest, or taiga (a Russian word) — the predominant forest region in Canada, stretching from the Yukon to the East Coast and making up 82 per cent of the country’s total forest area.

“I’m looking at long-term population trends, particularly population cycles (peaks and troughs) of small mammal abundance,” says Reid.

She adds that red-backed voles are the most common mammal at the TBS, as well as in the rest of Canada.

Dr. William O. Pruitt, Jr., of the University of Manitoba’s Department of Zoology and founder of the TBS, says the red-backed vole is intimately dependent on the future of the taiga, and the health of the animals is a key indicator of the health of the boreal forest.

He says Reid’s research helps explain how well plants and animals have regenerated around the Taiga Biological Station since a massive forest fire there in 1980.

One of the planet’s largest terrestrial ecosystems, the boreal forest covers roughly half of Manitoba’s land area, sweeping from the northwest to Whiteshell Provincial Park in the southeast.

The taiga plays a vital role in sustaining ecological cycles, including wildlife diversity and carbon storage, says Pruitt. This vast ecosystem — which consists mostly of white and black spruce, trembling aspen, paper birch and jack pine and is home to woodland caribou, moose, black bears and wolves — also provides timber resources from which we derive valuable wood products and jobs in our communities. Wetlands, composed of acidic peat bogs, fens and marshes, cover large areas of the taiga.

But the world’s boreal forest, “a resource of which Canada is the major trustee, is under siege” because of logging, energy and other development, according to a 1999 report of the Canadian Senate sub-committee on the boreal forest.

That’s why more independent, non-commercial research is required on the taiga, especially the interrelationship of its plant and animal species, says Pruitt.

The lack of information about the boreal forest prompted him to found the TBS back in 1973.

“I started the station to study the natural history of organisms of the taiga in a natural condition. You have to start at the source of those creatures in nature before you take it into the lab for analysis. What are the parameters of the natural conditions? You have to know this,” says Pruitt.

Flora and fauna

“We don’t know very much about any of the organisms in the taiga. We know something about the distribution of flora and fauna and something about some of the sexy mega-fauna, like black bear and moose. But for many of the mammals, we don’t know distribution levels, reproductive characteristics, numbers of young and how long it has taken them to mature.

“So, most of the taiga is a big blank with occasional blips of knowledge. The critical gap in our knowledge is of species other than humans.”

Upon finding a dead red-backed vole, shrew or deer mouse in one of her traps, Reid first records the plot location, a brief habitat description plus some other information on a brown paper bag before placing the small corpse inside the bag for a later detailed dissection by Pruitt.

“When the 1980 fire struck, the steep rock face acted as a chimney and the fire consumed all mature canopy,” says Reid.

She says the current jack pine saplings have all sprung up since the fire, while the lichens and moss are slowly returning across the rocks, as are the red-backed voles and related mammals.

In northern Finland and Scandinavia, biologists have found peaks in red-backed vole populations every three to four years, while in North America such cycles have not been detected.

“What I found at the TBS after plotting data, including my own, for the past 25 years is that we do get ups and downs in small mammal populations.

But, we don’t get a three- or four-year cycle here,” she says.

In the past five years, fungi and lichens have returned to the area and with that, the red-backed vole have been increasing, as well.

“All of this diversity of habitat in the taiga from jack pine ridges to mixed deciduous and coniferous forest is needed to support a healthy population of red-backed voles (and other creatures).”

Pruitt says Reid’s research eventually will lead to other important research by students.

“We desperately need to continue some sort of mechanism that enables students to do field work in the natural history of the taiga,” he says.

The TBS Web site is www.wilds.mb.ca/taiga