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Outdoors/Adventure

In Alaska, a mouse is not always a mouse

Mice are mice. Or are they? I remember catching mice as a kid. The ones I caught where I grew up along the Old Seward Highway were gray with long tails. My dad said they were “house mice.” Undoubtedly he was right. They sure liked our house.

House mice are not native to Alaska. However, there are plenty of them in Anchorage.

These transplanted visitors most likely came north on a ship or a container truck. Without a doubt, they are in Alaska to stay.

The inability of this medium-sized mouse to handle extreme temperatures has kept them from spreading outside of urban habitat.

The majority of what Alaskans term “mice” are red-backed voles. Red-backed voles are the most common of the five vole species found here. Voles are easily distinguishable from mice by their short tail. Tundra voles are also found in good numbers throughout Alaska.

A northern red-backed vole climbing down a tree (UAF photo by Todd Paris)

Tundra voles lack the distinctive reddish brown on their backs that distinguish red-backed voles. Singing, meadow and yellow-cheeked voles fill out the remainder of Alaska’s voles species. All are found outdoors.

Some voles burrow underground, others live exclusively in grass mats and under downed trees. Winter months they spend most of their time in the subnivean layer, the area between earth and snow. Low snow years, like this one, can be tough on the vole population. These tiny critters rely on an insulating blanket of snow to keep them from freezing.

Conversely, too much snow, or a layer of frozen snow, can cause carbon dioxide buildup, which drives the voles to the surface in search of oxygen. On the snow’s surface, they become easy targets for larger predators.

Alaska is known for its lemmings. The Disney movie “White Wilderness,” produced in 1958, depicted the mass migration/suicide of lemmings as a result of over-population. Disney staged the event, but the myth of lemming suicide continues to this day.

The three types of lemmings are found in Alaska. They are all similar to voles in body style and behavior. Lemmings live on the northern tundra and, like voles, may have rare population spikes that cause them to migrate in search of greener pastures. Mass suicide is not an option. Collared lemmings, found on the North Slope, turn white in winter.

Another “mouse” species is shrews. Six types live in Alaska and all but one are relatively common though rarely seen.

Shrews, like voles and mice, are nocturnal and seldom seen in the daylight. They are extremely small and rank as some of the tiniest mammals on earth. The rarest Alaska shrew is the tiny shrew. This little guy weighs less than a dime.

Despite their lack of size, shrews are ferocious hunters. They are insectivores, but also readily consume meat. They have few predators, because their smell and taste discourage most of the medium-size carnivores. It is common to find dead shrews laying on the snow, where they have been killed by foxes and left. Ravens and magpies will willingly consume shrews, though it is doubtful if either of these birds are major predators.

One of the strangest characteristics of shrews is their ability to physically shrink the size of their skull and brain during the winter months. Their skull will shrink by 15 percent, while the brain may see as much as a 30 percent reduction in size. Obviously these mammals aren’t going to get smarter with age. Shrews rarely live longer than 18 months anyway.

The only true mouse in our state is the meadow jumping mouse. Jumping mice are found throughout Southcentral. They prefer moist meadows but will also live on the fringes of woodlands. Jumping mice are built like miniature kangaroos with long powerful hind legs and short front limbs. They can jump at least three feet, more if startled.

Mice, shrews and voles are a welcome and necessary addition to our wildlife population. They provide an excellent food source for larger animals. All species rely heavily on insects and insect larvae for food. In years of unfavorable weather, some voles, especially red-backed and tundra voles, may invade our houses. But because structures are not their normal preferred habitat, they are relatively easy to eradicate.

Too many “mice” in the house can be a little more than irritating, but an occasional vole scampering through the garage can be viewed as an urban wildlife treat.

John Schandelmeier is a lifelong Alaskan who lives with his family near Paxson. He is a Bristol Bay commercial fisherman and a two-time Yukon Quest champion.

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