West Virginia Wildlife Magazine
“What’s That Clump of Leaves?”
By Art Shomo
Winter has come. Hardwood trees, stripped of their colorful fall garb, yield        secrets previously hidden from all but the most careful observer. “Hey,        there’s a new house!” “I’ve never noticed that cave        on the side of the hill.” “What’s that clump of leaves        in that tree—a bird nest?” Well, not quite. Many hunters and        wildlife enthusiasts could tell you quick as a wink that those leaf clumps        are tree squirrel nests.
Leaf nests are a common sight throughout West Virginia since the abundance        of oak, hickory, beech and tulip poplar trees usually provides a cornucopia        of food for tree squirrels. Three species of these arboreal acrobats inhabit        the Mountain State. At home in cities as well as rural areas, gray squirrels        live throughout our state. To the dismay of some people, but to the delight        of others, old bushytail is a master at breaking and entering all but the        most secure birdfeeder to dine on sunflower and other seeds.
Fox squirrels, largest of the tree squirrels, also reside throughout West        Virginia but are associated more with farmland than their gray cousins.        Preferring pine seeds to nuts, the small red squirrel lives mostly in the        eastern portion of the Mountain State where coniferous forests are most        abundant. All three squirrels are active year-round but may hole up for        several days during severe winter storms or periods of extreme cold.
Tree squirrels build two general types of nests: tree cavity dens and leaf        nests. Whether located in abandoned woodpecker holes or in natural cavities, tree dens offer better protection        from wind, rain and snow. Studies have identified another advantage. Squirrels        living in dens use less energy in maintaining their body temperature. Leaf        nests are common in woods that have a shortage of natural den trees. Oaks,        beeches, elms and red maples are favored by squirrels for dens or leaf nests.        Ground holes may be used as emergency shelters by tree squirrels.
Location of a leaf nest is important. Whether built near the tree trunk,        in a crotch where several small branches depart a large limb, or on a strong        limb, the ragged-looking nests are located at least 20 feet up in the tree.        One biologist found that most of the leaf nests on his study area were built        in conjunction with grapevines which provided additional support for the        nests.
Construction begins with a platform of twigs roughly woven together, upon        which damp leaves and moss are compacted to form a solid base. A spherical        skeleton of interwoven twigs and vines is erected around the base. The outer        shell is then completed with the addition of leaves, moss, twigs, and even        paper.
The inner nest cavity is six to eight inches in diameter and is lined with        shredded bark, grass, and leaves. This soft lining is especially important        to cradle the delicate infants which weigh about half an ounce at birth        and whose skin is almost transparent.
Nests of gray and fox squirrels may measure up to two feet wide and a foot        high. Red squirrel nests are proportionately smaller. Opposite the main        entrance, the wary bushytail builds a leaf-concealed escape hatch.
Durward Allen, a noted biologist, wrote: “From the ground, most leaf        nests look small and flimsy, although a closer examination shows that they        are by no means so frail as they appear. On several occasions after a rain        I evicted a squirrel and found its nest to be dry and warm.”
Second and third homes are popular with tree squirrels. More loosely constructed,        these secondary leaf nests are erected at varying distances from the main        nest. Having
several homes provides refuge from predators when squirrels        are out feeding and also allows squirrels to temporarily set up home when        food around their main nests run short.
Secondary homes are especially abundant in summer and frequently consist        of a pile of leaves and bark heaped onto a twig platform. A roofed-over        cavity isn’t necessary as the green leaves on the tree provide ample        protection. Sometimes leaf platforms or old bird nests are used for resting        during feeding and exploration bouts.
Leaf nests host a variety of activities throughout the year. The beginning        of a year finds squirrels in the midst of their mating period. Although        squirrels usually live alone, males and females may share their nest with        their mate for a short time during mating season in December and January.        Squirrels may also double up in a nest for warmth during winter.
During spring, females busy themselves with nursing and raising their young.        Young squirrels first venture outside the nest when about six weeks old.        The young usually leave the nest for good when 10 to 12 weeks old. However,        some of the spring litter linger until their mother is ready to have her        next litter in August (two litters per year is the rule in West Virginia).
Nest building activity mushrooms in June and July when the spring-born squirrels        practice building nests. These nests are often flimsy and seldom last long.        Also busy building or remodeling nests at the same time are pregnant females        about to have their summer litter. Adults may also build several temporary        nests during the warmer months. Fall is the most active time for nest construction        as both males and females prepare nests for winter.
In the author’s backyard, the resident squirrels usually move their        nest from the outer branches closer to the main tree trunk in preparation        for winter. Females with young don’t always stay in one nest. They        may shuttle their litters between leaf nests and cavity dens in response        to weather changes, danger from predators such as raccoons and snakes, or        parasite infestation. Sometimes females choose to defend their nest from        predators rather than move their young. More than one human has a battle        scar to show for fooling with a squirrel’s nest!
Leaf nests become a hub of activity, not only for squirrels but also a variety        of other creatures. Insects—spiders, mites, ticks, centipedes and        especially fleas—congregate in leaf nests.
The three species of tree squirrels in West Virginia seem to prefer den        cavities but will construct leaf nests where natural cavities are scarce.        Red squirrels use cavity dens extensively because hardwood trees, necessary        for leaf nest construction, are often scarce in the coniferous forests in        which they live.
John Burroughs, a famous naturalist of the late 1800s and early 1900s wrote: “One secret of success in observing nature is capacity to take a hint:        a hair may show where a lion is hid.” We might learn more things during our visits in the West Virginia woods if we heed Burrough’s words.        Winter reveals many hints: a clump of leaves may show where a squirrel is “hid”!
Art Shomo is the editor of West Virginia Wildlife and a public information        specialist stationed in Charleston.