Saturday, October 2, 2010

Adirondack Small Mammals: Mice

Another day, another blog. What to write about? I could muse about the preponderance of liquid precipitation we recently acquired (I am bowled over by how high the Hudson has risen). I could expound on my latest theory about birds having a sense of taste (based on the fact that they zeroed in on the few apples on my heirloom trees while ignoring the thousands of little green apples that laden the many feral apples trees in the neighborhood). But I think I will share with you an amusing experience I had at the library this morning.

I’d just walked in the back door and had set my laptop, my bag of files (transcripts, job notes, resumes, etc.), and such on the table. Grabbing the movies I was returning, I headed toward the front desk, only to be distracted by a movement on the floor. A small grey ball of fur, with a long tail, large ears, big black bead-like eyes, and large back feet scooted across the rug from underneath the book cart. It stopped, started, stopped, started, changed direction, zipped about.

“A mouse,” I stated, for all who were interested, which turned out to be zero.

“You have a mouse,” I repeated. One of the library staff looked up from her work. “What?”

“You have a mouse. On the floor.” I pointed at the rounded form as it scooted a little further across the lobby.

By now I had the head librarian’s attention. “A mouse? What should we do?”

I suggested we try herding it toward and out the front door, and managed to chase it behind the water cooler. A young man who was in the library offered to catch it. “Mice are my specialty,” he declared, and sure enough, in less than thirty seconds he flattened his hand on the mouse’s tail, scooped it up, and took it outside. I guess the mouse was less than grateful, for it bit its rescuer on the thumb. Perhaps it was unhappy to be evicted from what were no doubt pretty comfortable lodgings.

The ten cent question is, of course, “what kind of mouse was it?” (Okay, for some the ten cent question is probably “how did it get in here,” but I’m a naturalist, so I’m more interested in identifying it.) Based on the size of the ears and eyes, I was pretty sure it was a deer mouse or a white-footed mouse, and these two species can be very difficult to tell apart, even by the pros. In D. Andrew Saunders’ book Adirondack Mammals, however, the author lists some differences that one can look for.

For example, he writes that the deer mouse had softer, more luxuriant fur than the white-footed mouse. While that can be a bit subjective, his further description of the deer mouse being more grey above, and the white-footed more reddish- or orangish-brown, is a bit more telling. He also tells us that the white-footed mouse had a darkish brown band running down the back from head to rump.

The tails of these mice can also be used as a diagnostic. The deer mouse had a long, strongly bicolored tail (dark above, white below) that ends in a small tuft of white hairs. The white-footed’s tail, on the other hand, is merely pale below (as opposed to white), and lacks the terminal tuft.

While I noted that the library’s mouse was grey in overall appearance (and white below), I must admit that I didn’t get a close look at its tail. Still, based on the coloration I saw, I’m leaning toward deer mouse.

According to Saunders, the white-footed mouse is not quite as ubiquitous as the deer mouse. In the Adirondacks, it seems to be relegated more to the lowlands and the Park’s periphery, while the deer mouse prefers the higher elevations. Of course, there is overlap at the median elevations, but all things considered, I think I’ll stick with the deer mouse.

Both of these mice are in the genus Peromyscus, which is from the Greek and means “booted mouse.” I suspect this name was assigned because these rodents have white feet – kind of like socks (if they were horses), or mittens (if they were cats).

This is the time of year when, if you haven’t already mouse-proofed your house, you will likely find you have some of these wee guests taking up lodging for the winter. I hear them scurrying through my walls already, and occasionally I’ll see one scamper across my floor. Sometimes the cat does his job, but these days the dog is more likely to show interest than the cat.

Every year I find a cache of sunflower seed husks on the back porch, squirreled away (moused away?) under shelves or behind various containers used in my gardening endeavors. Sometimes I even find the little dears inside the birdseed bin; if they are lucky, they make it out alive. When the birds are not feeding, however, the mice are bound to perish – not from starvation, but from dehydration. It’s very sad – what a terrible way to go.

When the presence of mice in my house becomes problematic, however, I get out the traps, both live and snap. Because I don’t visit the basement very often, snap traps are set in the bowels of the house (I’d rather kill them outright than have them starve in a live trap). In the house, however, I stick to the live traps. When a mouse is caught, it is relocated…preferably several miles from my house.

Which brings up potentially controversial problem. In the summer, relocating mice is probably not a big deal, but by fall, and certainly in the winter, a relocated mouse is likely doomed: it is dropped away from its home range, its food stores, and its nest. If cold and starvation don’t kill it, something else probably will. While on an individual level this pulls at my heartstrings, on a population level it doesn’t bother me too much. There are plenty of mice to go around, and predators have to eat, too.

The next time you see a mouse scamper by, see if you can catch enough details in its appearance to tell which species it is. This could become a family project. Keep a tally of how many of each species you find. Who knows…a research project might come out of this and lead to a learned paper in a prominent journal. Careers could be made. I just hope you remember this article as your inspiration when you make your speech to accept the Nobel Prize in science.


Photo credit: http://www.esf.edu/aec/adks/mammals/deer_mouse.htm


Ellen Rathbone

Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.





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