
Chipmunks spend the fall hunting for food to keep in their underground burrows and sustain them through the winter. Russ Dillingham/Sun Journal
There is so much luck involved in spotting wildlife. I think about this all the time, whether I’m out looking for a rare bird or even just pointing things out during our walks at Gilsland Farm. We go to the right places, check the correct habitats, but at the end of the day, most wild animals don’t want to be seen by humans. This week, we got a fun series of questions from Dewey M. of Nobleboro around this concept of detectability of animals around their yard in winter, from the ever-present squirrels to the rarer porcupine sightings, so let’s think about these animals and why we do, or don’t, see them.
A good place to start: Who is active and when? We only have a few species of mammals that are true hibernators and remain dormant throughout the winter. Five of Maine’s eight bat species, those that overwinter in Maine, find hibernaculum to sleep the cold months away. The other three are migratory and depart to places farther south where food is available. Among our small rodents, there are only two that hibernate: Woodland and meadow jumping mice. And then one larger rodent, in the Sciuridae family, is the groundhog (aka woodchuck, whistlepig, Marmota monax). This is following the strict definition of hibernation, where heart rate, respiratory rate, and metabolic rate all drop, and body temperature drops significantly, nearly matching ambient temperatures. This latter trait is why black bears aren’t considered true hibernators; they keep their body temperatures up, an especially helpful thing for the females that give birth in their winter dens.
So pretty much all the other mammals are going to stay active, at least to some degree, and they have some pretty cool ways to survive. Without going one by one, because we could write a whole book doing that, I’ll mention that some mammals do go dormant for short periods in the winter, opting to save their energy when conditions are harsh or food is scarce. Skunks, for example, go from being regular backyard visitors to completely absent in the winter. Then, on the first warm(er) evening, you’ll smell the unmistakable perfume during your commute. Chipmunks are another fun one. They spend most of their winters underground. You may recall seeing eastern chipmunks running around in the fall with cheeks full of acorns, busily working to cache food in their underground burrows to sustain them throughout the winter. They also take advantage of the subnivean layer, that space between the surface of the snow and the ground, where they can tunnel around and forage. Other small mammals like eastern meadow vole and northern short-tailed shrew also tunnel around in the snow, and you can often see their routes in the snow after a melt.
One of Dewey’s questions was around the inadvertent feeding of a few species, like skunks and the occasional raccoon. These were taking advantage of bird seed that had spilled on the ground — which at that point basically makes it mammal seed. While this is generally not a problem for the animals, it is important to be clear that there is a point at which it can become a problem. That can probably be defined as the point when people start deliberately feeding wild mammals, which should not be done, for many reasons. It can lead to human-wildlife conflicts and can increase chances of disease transmission. I would even encourage people to cut back on bird feeding if they are noticing too many mammals (which I’ll leave undefined, but I bet you’ll know exactly when “too many” happens) visiting feeder stations.
As much as we may love seeing wildlife in our backyards, we do want to keep them wild. Rather than putting out food for them, you might want to provide more native plants that they can use seasonally. The plant finder at mainenativeplants.org is a great resource for narrowing down species that you can add to your yard to support wildlife; there is even a filter to search for plants that support mammals!
Have you got a nature or wildlife question of your own? It doesn’t have to be about birds! Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug and other naturalists lead free bird walks on Thursday mornings starting at 8 am, at Maine Audubon’s Gilsland Farm Audubon Sanctuary in Falmouth.
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