Two Common House-Invading Mice and a Shrew

(This column first appeared in the November 10, 1997 Buffalo News.)

    Each year at this time our homes are invaded.

    Through every crack and crevice it seems, crickets, wasps, spiders and even small mammals find their way into our houses.

    We may not welcome them but we can hardly blame them for trying to join us. They too have taken note of ever shortening days and have felt the chill of boreal breezes.

    Now is the time we have to guard against red or flying squirrels turning our attics into vast storage bins and to protect against raccoons or opossums or starlings scrambling down our chimneys to find room and board for the cold months ahead.

    My wife sets out mouse traps at this time of year. This is her defense against another invading force: meadow voles and house mice -- the country mouse and city mouse of the fable -- that seek shelter in our basement or attic. In previous years they have made winter nests in stored luggage and clothing, turning them into their version of Swiss cheese and effectively destroying them in the process.

    But already she has caught the wrong culprit. We found another short-tailed shrew in our trap in the garage. This is the third year this has happened and I do not understand why. Perhaps this little beastie was driven inside by the recent rains. More likely he and his predecessors of previous years were after still earlier invaders: arthropods or even mice. But we've trapped no mice yet this year.

    It would have been easy to mistake this shrew for a mouse. That is even suggested by one of its common names: shrew mouse. There are differences between the short-tailed shrew and these two common mice of our area but their general size and shape is similar. That ephemeral view you usually get of the little furballs skittering into hiding is seldom enough to differentiate them.

    Although the vole is almost twice as heavy as the others, size is not a good basis for identification as you would never see them together for comparison. If they did meet, the shrew -- a violent carnivore -- would immediately kill either of these mice -- herbivores with few defensive skills -- and make a meal of it.

    Found in a trap as this one was, it is easy to separate the three. If the captive has big ears and a bare tail as long as its body, it is the house mouse. As soon as it is eliminated, distinguish the other two by body color and eye size: The vole's back is brown, the shrew's is lead gray; the vole has big eyes, the shrew's are tiny. There are other differences and specialists can identify small mammals by what they call "jizz," a sense of their general appearance and activity gained through experience. The rest of us see these little furbearers so seldom that we don't have a chance to develop that kind of skill and most don't want to anyway.

    Shrews belong to an entirely different order from rodents like mice. That order is Insectivora, the name an indication of a diet staple although they also feed on earthworms, snails, spiders and mice. Moles also belong to this order.

    Most wild animals bite in self-defense, but the shrew's bite carries a tiny dose of a cobra-like venom that often leads to local but usually minor and short term irritation. Although these aren't rabies carriers, your best bet is not to handle any of them.

    Doris's traps are baited again, but I hope the predicted El Nino-influenced mild winter will keep these little animals outside skampering about their snow-covered tunnels.