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
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
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
Art Shomo is the editor of West Virginia Wildlife and a public information
specialist stationed in Charleston.