Winter is Mouse Season

Nov 18, 2019

This is the time of year when mice invade your home. Well maybe not yours, but definitely the home of the Masked Biologist, as he shares in this week’s Wildlife Matters.

I hate mice. Sounds like a mean thing for a biologist to say, doesn’t it? normally, you tune in and hear me talk about some fascinating animal and what I love about it, what makes it unique. And here I am hating mice. When I say I hate mice it’s because back in college I simply could not pass my rodent test in mammalogy. There are way too many mice, and it is a lot of work to tell them apart. You have to be able to remember how many dentine lakes on which molar represented which species. Or maybe a smooth lingual face on the upper third molar would tell you it was this mouse instead of that mouse. Other mammals were far easier to distinguish. You could discern between foxes, for example, or felines. Even squirrels and chipmunks had reasonable external features you could identify and describe. But I had no interest at all in being a mouse dentist.

Okay, in truth I don’t hate mice at all. I rather like the rodent family; if you think back, you have heard me talk about squirrels, chipmunks, porcupines, and even our largest rodent, the beaver. But I have never written or talked about mice, except when I list them as one of the animals eaten by birds, snakes, or other mammals.

I am thinking about mice because it is the mouse season. When we were winterizing our camper, we found mouse droppings. in our house, up in the kid’s closets, mouse droppings. Down in the basement, more mouse droppings. we had mice everywhere. It seems in the fall there is a flurry of mouse activity. I think that non-hiberating mice seek out warm, dark, dry locations to wait out the winter. And, with our old house with its rock walls, mice have no trouble getting in. Then all they have to do is wait until after the late news to go and gather up nesting materials, goldfish crackers and bird seed. Unfortunately for them, they also like peanut butter. Or at least they did. I set several snap traps around the house, and caught over a dozen in short order. They have stopped licking the traps clean, though, so I think maybe I have reclaimed my turf. You can never be too careful, though. One female can raise four to five litters of four to five young in a breeding season. That means one family could add 16-25 or more young mice to an area, and they can live four years or more in the wild.

I don’t know what kind of mice they were. We have over a dozen kinds of mice and voles in Wisconsin, several of which live up here in the Northwoods. I think based on the eyes, ears, and tails that they were white-footed deer mice. They didn’t look much like field mice. When I used to set pitfall traps in the field, I would just call these Peromyscus species, which gets you close enough. Deer mice in the house or yard should be taken seriously, because they carry bacteria and spread disease. Diseases like anaplasmosis and Lyme disease come from ticks feeding on white-footed mice and other rodents, not deer. Mice carry hantavirus and salmonellosis too. And they freak you out with their big bulgy eyes.

You should never set out poison for rodents, as this could be hazardous to pets and wild animals alike. Use humane kill traps or live traps to remove rodents from living areas. Thoroughly clean and disinfect locations where you find their droppings. discard any food containers or household items chewed on by mice. Wear gloves when disposing of mouse carcasses, and if you use poison, make sure to dispose of them away from wild animals, children, or pets.