This past spring, when we went up to the cottage, we spoke to a local guy who said there had been no mice that winter. He said it was because of the voles. But I thought voles are mostly vegetarians. So how could voles drive the mice out? Where did all the mice go? —Margo and Ivan Gullickson, Uxbridge, Ont.
If you’re thinking “voles don’t eat mice,” you’re right. For the most part, they don’t even eat the same food as mice. (Species example: meadow voles feed on grass, leaves, and roots, and deer mice feed on seeds, berries, and insects.) And they also don’t tend to use the same habitat. “Voles seem to appear rarely in cottages and cabins. Deer mice are the usual culprits,” says Tom Sullivan, a professor emeritus in wildlife biology and conservation with the University of British Columbia. So our experts think it’s unlikely that an increase in voles could cause a decrease in mice pests. “I would assume the two groups are simply independently fluctuating out of synchrony,” says the University of Illinois’ Lowell Getz, who has authored several papers on vole populations.
Food, predators, weather, diseases, and stress can all play a role in population ups and downs. But, says Sullivan, a “site-specific” decrease in mice—at one cottage, say—is more likely because predators have moved into the area. “If predation is responsible, and the predators move around to new sources of prey, the mouse numbers may recover.”
Translation: just because there were no mice last winter doesn’t mean that you’ll be mouse-free this winter. Rats.
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