Squirrels are nimble, bushy-tailed rodents found all over the world. They belong to the
Sciuridae family, which includes prairie dogs, chipmunks and marmots.
There are more than 200 species of squirrels and they are categorized into three types: tree
squirrels, ground squirrels and flying squirrels. Wisconsin has 5 native species of squirrel:
Eastern Grey Squirrel, Sciurus carolinensis
Eastern Fox Squirrel, Sciurus niger
Red Squirrel, Tamiasciurus hudsonicus
Northern Flying Squirrel,Glaucomys sabrinus
Southern Flying Squirrel, Glaucomys vilans
All five species are popular with people who enjoy watching wildlife, although flying
squirrels, because of the nocturnal habits, are rarely seen. As abundant animals low
in the food chain, squirrels are important prey species for many mammalian and avian
predators.
They are huge contributors in shaping plant composition due to their eating and food
saving habit. While they eat seeds and nuts though they have this peculiar habit of
burying some of them for future consumption throughout the environment for later, but
their forgetfulness helps the ecosystem to thrive.
The seeds or nuts they stored later sprout and grow into trees. After a considerable
amount of time this caching leads to altering the composition of the forest. New types
of trees become present in the forest. Over a long length of time, the forest can even
expand.
Another important role of squirrels in the ecosystem is being a food source for other
animals. They hold a significant place in the natural food chain and are preyed on by
several avian and mammalian predators. Squirrels become food for air and land predators.
To determine the health of a forest ecosystem, and to measure how well it is doing,
researchers take into account the population of tree squirrels there. Demographics of
squirrels are important indicators for a forest’s condition, and these can be studied to
determine the impact of climate changes, global warming, logging, fires, and other events
on forest habitats.
| Eastern Grey Squirrel |
| Length: |
18-21 inches |
| Tail Length: |
8-10 inches |
| Coloration: |
Yellowish brown summer coat becomes thicker and gray in winter |
| Lifespan: |
1-2 years |
| Gestation: |
40-44 days |
| Litter Size: |
1-9 (average 2-3) |
The deciduous forests of Wisconsin provide the optimum habitat for the eastern
gray squirrel. Home for an eastern gray squirrel may be a leafy nest, a dome-shaped
mass of twigs and leaves with an inner chamber of shredded bark and leaves, or a
tree cavity which it seems to prefer.
The principle foods are seeds and nuts with acorns, beechnuts, butternuts, and
hickory nuts providing the mainstay of the autumn and winter diet. Beech and nuts,
because of their relative abundance in parts of the Adirondacks, make the greater
contribution. The smaller seeds of maples, ashes and basswood are of lesser importance.
The buds, flowers, and inner bark of all these species, and others, contribute to the late
winter and spring diet. Gray squirrels feed extensively on fungi, berries, and fruits during
the summer, especially the fruit of the black cherry.
| Eastern Fox Squirrel |
| Length: |
21 inches |
| Tail Length: |
8-10 inches |
| Coloration: |
Gray and black fur on its back and orange-colored fur on its belly |
| Lifespan: |
Average is 7 months |
| Gestation: |
44 days |
| Litter Size: |
3-4 |
Eastern Fox Squirrels, like other tree squirrels, use trees for escaping from
predators. They are fast and agile in the trees. They can readily escape
predators on the ground and large birds of prey if they can seek refuge
in the trees. Fox squirrels are found in a diverse array of deciduous
and mixed forest. Areas with a good variety of tree species are preferred
due to variability in mast production.
A wide variety of foods are taken, ranging from vegetative matter to gall
insects, moths, beetles, bird, eggs, and dead fish. Acorn, hickory, walnut,
mulberry, and hawthorne seeds are preferred. Food can often become
limiting in the winter, so squirrels commonly cache seeds in a scattered
fashion for the colder months. Nuts are opened by a levering technique
of the lowering incisors, a skill at which squirrels become proficient quickly.
| Red Squirrel |
| Length: |
10-15 inches |
| Tail Length: |
3-6 inches |
| Coloration: |
Reddish back and white underside with dark colored lines |
| Lifespan: |
Average is 5 years |
| Gestation: |
35 days |
| Litter Size: |
1-8 |
Red squirrels occupy coniferous forests abundant with conifer
seeds, fungi, and interlocking canopies. Populations of red squirrels occur in
different habit conditions due to the vastness of their range. They
are considered to be primarily arboreal. They can be found in a mixed variety
of forests including coniferous, deciduous, and mixed forests and they are also
able to thrive in suburban and urban settings, as long as cool, coniferous forests
with dense, interlocking canopies and abundant fungal resources are present.
The Red Squirrel eats a wide-variety of foods including insects, seeds, bark,
nuts, fruits, mushrooms and pine seeds or cones. Sometimes it eats insects,
young birds, mice and rabbits. A large part of its diet is made up of pine seeds.
In the fall, it will cut green pine cones from trees and store them in the ground.
It also stores nuts and seeds in piles or middens under logs, at the base of trees
and underground.
| Northern Flying Squirrel |
| Length: |
10-13 inches |
| Tail Length: |
3-6 inches |
| Coloration: |
Silky grey and cinnamon brown fur, with white tipped and grey based
belly hairs |
| Lifespan: |
Average is 4 years |
| Gestation: |
37-42 days |
| Litter Size: |
1-6 |
Most often found in areas dominated by conifers, northern flying squirrels
can also be relatively abundant in deciduous and mixed coniferous/deciduous
forests. The Northern Flying Squirrel has been found in diverse areas including
regions dominated by spruce, fir, and mixed hemlocks, in beech maple forests,
and in areas dominated by white spruce and birch with interspersed aspen
groves. The Northern Flying Squirrel often nests in conifers 4-50 feet above
the ground. The nests are made of twigs and bark, and they are softened with
feathers, fur, leaves, and conifer needles. They clumsy on the ground, but can
glide gracefully from tree to tree.
The Northern Flying Squirrel eats nuts, acorns, fungi, and lichens, supplemented
by fruits, buds, sap and the occasional insect and bird egg. Northern Flying Squirrels
diverge from many squirrels in that lichens and fungi are a large portion of the diet
and are not just supplements. It is thought that northern flying squirrels hoard food
for the winter, though this has not been confirmed.
| Southern Flying Squirrel |
| Length: |
11 inches |
| Tail Length: |
3-6 inches |
| Coloration: |
grey brown fur on top with darker flanks, and are a cream color
underneath. |
| Lifespan: |
Average is 4 years |
| Gestation: |
40 days |
| Litter Size: |
2-3 |
Southern Flying Squirrels are commonly found in beech-maple, oak-hickory,
and poplar forests.Southern flying squirrels are nocturnal animals. They occasionally display
social behavior and can be found in pairs. In order to conserve heat during
the winter months, these rodents form groups of 10 - 20 squirrels, which
huddle together in a den, typically located in a hollow tree. Southern Flying
Squirrels do not hibernate. In spite of their name, these rodents don't fly, but
glide. During the 'flight', they are able to avoid trees and other obstacles with
ease. Moreover, they can glide from a height of up to 60 feet.
As omnivorous animals, Southern flying squirrels have a rather diverse diet.
They feed upon nuts, acorns, seeds, berries, fruit, moths, june bugs, leaf buds,
bark, eggs and cheeks of birds, young mice, insects, carrion as well as fungus.
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