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Rodents deal with the coming of winter

A deer mouse (white-footed mouse) seeks seeds for its cache. (Photo by Larry Weber)1 / 2
A chipmunk feeds in preparation for the coming cold. (Photo by Larry Weber)2 / 2

For the first two-thirds of November, the month felt more like that of October. Temperatures were much above normal; we recorded 50 degrees or warmer during 12 of the first 18 days. And so, we had no snow or ice cover.

But things began to change, not with snow and cold, but with rain and wind. Once the 2-inch rain and winds subsided, I went out to visit the swamps and ponds. This is a regular November ritual for me. I always want to see how high the level is on these small bodies of water before the freeze-up. And thanks to these rains, they all are holding plenty. All held water, no ice.

Almost on schedule, these same ponds were ice-covered the next day as the anticipated cold finally arrived. Though we did get some rain that changed to snow, it was not much, nor did it cover much. The cold was able to penetrate the ground. Are we now at freeze-up time? Will ponds and lakes keep the ice and the frozen ground hold a lasting snow cover? Is our wintertime beginning?

At this time of year, we take note of these changes and prepare for the coming cold. We are not alone in this preparation. Other critters that live in the Northland need to deal with this annual change as well. Nature has come up with four ways for the wildlife to cope with cold and the long dark winter. Many small critters, especially insects, will die as the frosts of fall move in. Before they succumb to the cold, they lay eggs in various protected sites to insure the presence of their kind next year. As late as Nov. 15 I saw a dragonfly, moths and crane flies. Most likely, they did not last long after. Among the birds and bats, those that are with us in the warmer times leave to migrate to milder climates south.

Not taking either of these options, a group of our local residents go off to sleep throughout the cold. This long nap is usually referred to as hibernation. There are many variations in this wintering strategy and a diversity of winter sleepers exists here. We usually think of hibernation being bears and woodchucks, but so do snakes, frogs and many insects use this dormancy type of protection. And there are those that make a few adaptations to their diet and coats but continue to be active through the whole cold season. In our area, this is seen mostly with birds and mammals. Looking out nearly every day we will see birds at the feeders or tracks of active mammals that tell us of their persistence in the chill.

As we have been going through these days of AutWin this year, I have been observing two kinds of rodents, both very common in the yard and woods, that choose two different ways of coping with winter: chipmunks and deer mice, or white-footed mice. Though deer mice and white-footed mice are slightly different, most of us find it hard to tell them apart. Both live here, but deer mice have a range extending further north.

It seems like every day throughout October and early November, the diurnal chipmunks have been arriving in the yard to gather seeds for caching in their wintering den. The bird feeders, the compost piles or nearby fruit trees were the source of discovery. The little ground squirrels with stripes on their face and sides then go off to store food for winter snacks. When enough has been carried off — maybe more than enough — and cold dark weather moves in, they will go to sleep in the den.

Why bother to store food if they sleep? Though we often say that chipmunks hibernate, their sleep is not complete. They wake periodically in the winter, relieve themselves, have a bite to eat and go back to sleep. A few times I have seen these small rodents in January.

Meanwhile the other common rodent resident, the deer mouse, takes a different approach to the coming winter. During their nocturnal rounds in autumn they seek food and shelter. The food, mostly seeds and nuts are also cached. With a high population at this time, shelter becomes important and they may move into sites already occupied, by us.

It is now these cute mice with two-toned fur, big eyes and big ears will invade our houses, garages and cabins. Here they may use our materials to make a snug nests and cache food in various sites. It is not unusual to find seeds and nuts in shoes, shelves or even on the engine of a car and they move in and they are not so cute anymore. Though they do not hibernate, we might wish they did. Winter can be hard for these mice and even without our intervention, many die in the cold or by predators, as the chipmunk sleeps. Two common small rodents, two different ways of coping with winter.

Retired teacher Larry Weber is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods” and “Webwood.” Contact him c/o budgeteer@duluthbudgeteer.com.

Larry Weber

Retired teacher Larry Weber is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods,” “Webwood” and “In a Patch of Goldenrods.” Contact him c/o budgeteer@duluthbudgeteer.com.

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