Cool weather is a fine time for harvesting produce, fertilizing the lawn and checking for mice. Checking for mice? you might ask. Well, it's true, cool weather brings those miniature eating machines indoors looking for a place to cozy up for the winter. Having dispatched 30 mice in five weeks from my pump house and hay barn, I'd have to say that thoughts of them still gnaw at my brain and I continue to set traps.
Mice, along with their habit of stealing food, have followed humans down thorough the ages. Even the word "mouse" can be traced back to the Sanskrit word musha, which means "to steal." And frankly, I'm tired of their stealing. The mice don't seem to bother the chickens or their eggs in the barn, but they do eat the grain put out for the hens, and knowing that they eat and foul the hay with their urine and droppings is enough to gag a horse.
They say there's never just one mouse; that's because rodents have large extended families. House mice have a long breeding season with a gestation period of only 21 to 24 days. They become sexually mature in two to three months and have an average of five per litter. A single female can have up to eight litters a year--you do the math.
I've become the top cop on mouse patrol on my property, even though I own five barn cats. You'll find me in the barn at night with a flashlight setting mousetraps with Gorgonzola cheese. That's right, my mice are connoisseurs. Peanut butter got boring for them and plain cheese just wasn't smelly enough to be attractive, but place a bit of Gorgonzola on the trap and the little nibblers will race to be sacrificed.
The house mouse's country cousins, the short tailed voles are sometimes called field mice. Voles live outdoors and are the ones who engineer those half pipe runways in the grass under snow. Together, the two rodents can destroy young trees and shrubs by stripping bark above and below ground in windbreaks, orchards, Christmas tree plantations, nurseries, and yes, even in landscapes close to open fields. Dense beds of ground covering junipers are favorite havens for rodents. Their handiwork shows up as dry, dead branches scattered here and there in the planting. Follow the dead branch back to where it joins the main trunk and you'll see where the little buggers have chewed the bark off.
Mice compete with livestock for pasture grasses and forbs (non-grass plants). Their tunnels hasten erosion, especially on steep slopes, and they can destroy the eggs of game birds. In buildings and parked vehicles (that have sat idle for long periods), rodents can chew insulation off wires and munch holes in hoses. They are definitely destructive critters, especially when their numbers skyrocket. Vole populations can rise as high as 200 animals per acre! And if all that damage isn't enough, we have mice and other rodents to thank for spreading plague-carrying fleas. There are 14 genera of rodents that hold that honor.
Rocky Mountain Spotted Fever, carried by ticks, has been isolated from rodents (as well as rabbits, sheep and dogs). The hantavirus, another serious health threat for humans, is commonly carried by the deer mouse, who's easily identified by its white feet, white stockings and white underbelly. This mouse has bigger ears and eyes than a normal house or field mouse. Deer mice, luckily, are not common in urban areas.
So why don't rodents proliferate and overrun the planet? Probably because great numbers of them are eaten by hawks, owls, foxes, coyotes, skunks, weasels, mink and snakes. Those predators are wonderful allies in demousing (my word) an area. Cats can help, too, if they aren't too fat and lazy from a pampered life.
Sanitation is also important in keeping mice populations in check. Put garden seeds and grain into metal garbage cans with tight-fitting lids. Because mice can squeeze through small cracks, use door sweeps to eliminate space under doors. Rodents can gain entry where utilities like plumbing and wiring enter a building; remember to seal those overlooked pathways. Eliminate grass and brush close to buildings to remove the precious cover that rodents need.
To prevent the hairy little thieves from chewing young trees, mow or remove high grass cover in a three-foot radius around young fruit and ornamental trees. The trunks can also be encircled with half-inch mesh hardware cloth for added protection. The mesh should be set into the ground three inches and extended 20 inches above the soil surface. Higher guards may be needed where deeper snow is expected. Rodents work under the cover of snow in winter. For them, it's like a big blanket.
Poisoned baits are available, but not recommend in areas where pets or birds might find them. Keep in mind that bait-killed mice can be a hazard for pets and other wildlife later if eaten. Trapping is a safer alternative. Use peanut butter, oatmeal, apple slices or cheese for bait and don't be squeamish. (They can't bite you once they're dead.) I bury all the dead burrowers in my compost pile; it seems a fair trade. My gardens will eventually be enriched with their nutrients, and I have the satisfaction of getting at least some return on what was originally stolen. R.I.P.
Suzann Bell is a horticulturist with the University of Idaho Extension Service in Ada County. Send gardening questions to Suzann, c/o Boise Weekly, or e-mail: firstname.lastname@example.org.