Small mammals

Katie Finch For The Audubon

On a recent exploration of the snowy landscape with day campers, animal sightings were few but evidence that animals were there was abundant. We followed deer tracks, poked at holes and investigated scratches. Almost overlooked were very tiny tracks. Just a light impression made on the freshly fallen snow. The pattern looked like a thin, almost unbroken line with tiny pairs of dots every quarter inch or so straddling the line. They started at the base of a tree and stopped at a hole in the snow less than an inch in diameter.

“What’s that?” a camper asked.

“What do you think?” I said.

“A mouse.”

“Why?”

“Because they are tiny. And the line is a tail.”

“Are mice they only tiny animals?” I asked.

And so launched a discussion about what small animal might be out and about in the snow. Here are our options.

The tracks we saw were most likely made by a shrew, a mouse or a vole. They are all mammals who, with special adaptations, live out their lives both above and below the snow during the winter.

The smallest of these is the shrew. Individual species can range from two to four inches long. One species, the Least Shrew, is about the size of an adult human thumb.

There are several species of shrew in this region, all with sharp, front teeth for catching and eating mainly insects but also worms, centipedes, snails, spiders and more. Shrews don’t store food but are almost constantly hunting and eating to satiate their incredibly high metabolism. Once species, the Short-tailed Shrew has a unique mammalian adaptation to catch its much needed food. Its teeth are equipped with venom that slows down and in some cases kills prey, even those that are slightly larger than the shrew.

Shrew are common but rarely seen. They don’t tunnel in the earth like moles but move through vegetation, other animals’ tunnels and under the snow. If you were to see one, you could recognize it by its long, pointy face, tiny eyes and lack of visible ears. In the winter, evidence of shrews is left by their tracks and trails. The pattern of tracks is an inch or less wide with individual tracks on either side of a line which is made by their tail dragging on the ground. If the trail ends in a hole, brush pile or next to a tree, the hole will also be about an inch wide. Their trails under the snow are often visible as the snow begins to melt.

Next up is the mouse. Like shrews, there are several species of mice in this region. One species, the Jumping Mouse is a true hibernator, spending the winter in a burrow waiting out the cold. The two most likely out in winter are the Deer Mouse and White-footed Mouse. They move across the surface of the ground and snow, leaving tracks behind that look like miniature rabbit tracks- wide back feet and narrow front feet with an occasional tail drag. They are generally not tunnel diggers but they are good climbers. Their hopping tracks can be seen leading to a tree, bush or something else to climb where they build their nest or cache a wide array of food including nuts and seeds.

The last, but not the least – it’s actually the biggest – is the vole. No, that’s not a typo in which I meant mole. Voles are small rodents that tunnel, not into the soil but through grass and similar vegetation, eating as they go. The Meadow Vole and Woodland Vole, species common in this region, eat insects on occasion but are mainly herbivores chowing down on grass and a variety of roots, stems, seeds and fruits. Because plant material can be tough on their teeth and is difficult to digest, voles have two interesting (or disgusting, depending on your perspective) adaptations. One is that their teeth constantly grow, much like our fingernails. And, to get the most nutrients from the plant material they eat, they reingest their feces. Yup, they eat their own poop.

While you may not see this small, stocky mammal easily, you can go into field, marsh (or your yard) and see vole tunnels under the grass or snow. In winter they will occasionally pop above the snow and leave tracks similar to a shrew but a little wider and usually without a line from their tail dragging. The holes where they enter their hidden life again are one to two inches in diameter.

“What about the mole?” you ask. Moles are active in the winter but spend most of their lives in underground tunnels so the tracks we saw were most likely not made by a mole. Given the size, pattern and distinct tail drag, I think they were made by a shrew.

It is unusual to see these small creatures as we, comparative giants, go about our business. Unless they get caught in a trap, by a cat or we are looking for them, their presence may go altogether unnoticed. But our ignorance of their presence does not negate their existence. They are noticed by mink, fox, hawk and owl, all who depend on these small yet abundant mammals for food.

Audubon Community Nature Center builds and nurtures the connections between people and nature. The trails are open for hiking or skiing from dawn to dusk and the Nature Center is open from 1 p.m. – 4:30 p.m. daily except Saturdays when it opens at 10 a.m. Visit auduboncnc.org for more information or call (716) 569-2345.

Katie Finch is a naturalist at ACNC.

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