Wild Life
by Alicia Daniel

Squirreling Away Food for Winter

On a warm October day when sunlight filters through the dazzling fall leaves, it may be tempting to lie down and take a nap on the dappled forest floor. However, if your forest contains oaks, your nap may well be interrupted by the frenetic rustling noises of gray squirrels harvesting and burying acorns for winter. You may also see them carrying leaves and shredded paper up to the tops of trees to line their nests or drays.
Charlotte’s tree squirrels (red and gray), flying squirrels and ground squirrels (chipmunks) must work hard this time of year in order to survive the harsh winter season. A typical squirrel diet consists of a variety of foods such as seeds, nuts, berries, some leaves, buds, mushrooms, acorns, flowers, fruits, fungi, lichen, sap, carrion, insects and sometimes birds’ eggs. But each species tends to specialize, especially when it comes to caching food for winter. With a bit of luck and some finely tuned behaviors, these small animals will live to greet the spring. And as they go through fall and winter they leave a trail of clues about how they manage to survive.
From your prone position on the ground you may see bouquets of oak leaves still attached to straw-sized twigs cascading down from the tops of oaks. Gray squirrels snip the ends of thinner branches to get acorns from the edges of trees where the fine branches cannot support their weight. (Similarly, you will see branch ends of white cedar lying around the base of the tree that red squirrels clip in order to get at the cones.)
Gray squirrels hoard acorns, hickory and other large nuts by scattering them in different places throughout the woods within a roughly one-acre home range. The squirrels find these buried nuts by using their acute sense of smell, not by remembering where they put them. This winter when you walk in the woods, you can look for plum-sized holes scattered in the snow where some of the duff has been pulled to the surface. Sometimes, if you look closely, you will see the acorn-shaped depression frozen in the dirt at the bottom of the hole. Then you will know that a gray squirrel ate lunch where you are standing.
And chances are good that the acorn he ate was a red one. Gray squirrels tend to store red acorns, which are higher in tannins, both because they preserve better and because they are less palatable than the white oak acorns. Squirrels tend to eat the tasty white oak acorns immediately. Red oak acorns also germinate in the spring instead of the fall so they don’t sprout before the squirrels can recover them.
Unlike gray squirrels who are scatter hoarders, red squirrels are larder hoarders. Red squirrels are more dependent on seeds than nuts for their winter food. They tend to pile food up into little hills called middens. These middens consist of cone cores and old bracts under which fresh cones are stored. The cool moist temperature keeps the cones from opening and the seed from being released. Also look for winter sign of red squirrels feeding where there are pinecone cores and bracts in the snow near the base of a stump or tree.
Vermont naturalist Bernd Heinrich has recorded another interesting squirrel behavior. He has observed red squirrels tapping into the sweet sap of red maple trees. Bernd saw squirrels biting the bark of sapling maples and returning to lick the sugary popsicles once most of the water had evaporated. Look for wet slicks of sap on maple saplings. And if you look closer, you will see bite marks that show where the red squirrel bit the tree.
Signs of flying squirrels are more subtle. Flying squirrels are nocturnal, so much of their winter preparation happens under the cloak of darkness. Unlike the other squirrels, lichen and fungi are a large portion of the flying squirrels’ diet. These foods leave less winter evidence than nuts and pinecones. One way to observe their presence is that they tend to nest in cavities made by birds such a woodpeckers and chickadees. Look for a hole that has teeth marks all around the edge. I once opened a blue bird nest box that had the opening enlarged by gnawing and startled a pair of sleeping flying squirrels. Some naturalists will bang on the trunks of trees where there are nest cavities to flush the squirrels. (I recommend you don’t make this a regular habit, especially at the same tree, since it stresses the animals.) Because of their large eyes and draping skin flaps, flying squirrels have a sweet, soft appearance. And yes, they really do fly – or glide – from tree to tree as a way to conserve energy. When they end their glide by landing in snow you can see a distinctive skid mark.
In the fall, chipmunks are easy to spot scurrying in and out of crevices in stone walls and running up and down the trunks of trees caching their winter stores. They have internal cheek patches for carrying food. Their bulging cheeks, bold stripes and flashy strobe motions add to their charm. Of the Charlotte squirrels, they are the only true hibernators, so winter signs of them are scarce. Unlike most ground squirrels, which store fat for energy during dormant periods, chipmunks have large underground caches of food for the occasional periods of waking and for use in early spring in areas still covered by snow.
Did you finish your nap? Or did the squirrels keep you awake? Well, brush yourself off and look around the forest floor for signs of the nuts the squirrels just buried. You won’t find any. Squirrels are masters of disguising where they have buried nuts by scuffing and fluffing the leaves. But if you return here come spring, you will see evidence of their work. Inevitably, some buried acorns escape detection and germinate. Oak seedlings will be unfurling their delicate leaves. The massive oaks they will become will feed the descendents of the squirrels you watched all those years ago in these October woods.

Field Naturalist Alicia Daniel is a big fan of forest naps and flying squirrels.

WILD LIFE nature notes are provided by Charlotte Conservation Commission in collaboration with some of the many talented naturalists in this area. Send comments and suggestions to Linda Hamilton (ferntip@gmavt.net, 425-5795).