“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 em ergency 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.

