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fox squirrel

Sciurus niger

What do they look like?

Fox squirrels are medium-sized tree squirrels with a long, furry tail. Fur color varies greatly in this species, from overall pale grey to black with white feet. The most common fur color is reddish-brown. Often the hairs are reddish tipped with brown, giving these squirrels a frosted look. The fur on their belly is always lighter in color.

Fox squirrels have very sharp claws and muscular bodies. This enables them to climb trees and other objects extremely well.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    696.0 to 1233.0 g
    24.53 to 43.45 oz
  • Average mass
    800.0 g
    28.19 oz
  • Range length
    454.0 to 698.0 mm
    17.87 to 27.48 in
  • Average length
    595.0 mm
    23.43 in

Where do they live?

Fox squirrels are found throughout the eastern and central United States. They occur as far south as northeastern Mexico and as far north as south central Canada. They have been introduced into cities in the western United States as well.

What kind of habitat do they need?

Fox squirrels prefer open, savannah-like habitats, where trees are widely spaced and the understory is open. They are most common in oak-hickory forests but are also found in live oak, mixed forests, cypress and mangrove swamps, and pine forests. Because of this habitat preference they tend to do well in urban and suburban settings. They are rare in heavily forested areas, unlike their close relatives grey squirrels.

Fox squirrels need large trees with cavities or holes in them for building nests to raise their young. They may use these cavities to hibernate in during the winter as well. They also build leaf nests, a collection of leaves in the branches that are used by adults. They build the leaf nests high up in larger trees. They usually use large oak, elm, and other hardwood trees.

How do they reproduce?

Females can mate with several males, but the males will compete with each other to determine who gets to mate first.

Fox squirrels can mate all year long; however, most mating occurs in two mating seasons on from December to February and another from May until June. Females can begin to have babies at 6 months old and have one or two litters per year. Males can begin to mate at 10 to 11 months old. Female fox squirrels are pregnant for about 44 days. Average litter size is 3 young but it can range from 1 to 6 young per litter.

Babies are born without fur and weigh 13 to 18 g. They develop fur after 14 days old. They open their eyes at about 30 days old. They begin to explore outside of the nest after about 7 to 8 weeks. They don't travel much on their own until 3 months of age.

  • Breeding season
    Breeding occurs from December to February and May to June.
  • Range number of offspring
    1.0 to 6.0
  • Average number of offspring
    3.0
  • Average number of offspring
    3
    AnAge
  • Average gestation period
    44.0 days
  • Average gestation period
    44 days
    AnAge
  • Average time to independence
    3 months
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    353 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    1 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    353 days
    AnAge

Female fox squirrels care for their young in the nest for 6 weeks. When the mother leaves her young in the nest she covers them with nesting material. Young fox squirrels move away from their mothers in the fall of their first year. Male fox squirrels disperse farther and may die more as a result.

How long do they live?

Fox squirrels have been known to live to 18 years old in captivity. Under natural conditions the average lifespan is 8 to 18 years old, though most squirrels die before they reach adulthood.

  • Range lifespan
    Status: captivity
    18.0 (high) years
  • Average lifespan
    Status: wild
    7.0 months

How do they behave?

Fox squirrels spend most of their time in trees during the day. They live in small family groups whose home ranges overlap. They are not territorial but they will defend food and nest sources from neighboring squirrels.

How do they communicate with each other?

Fox squirrels have excellent vision, even in dim light. They have well-developed senses of hearing and smell. Fox squirrels also have several sets of vibrissae. Vibrissae are thick hairs or whiskers that are used as touch receptors to sense the environment. These are found above and below their eyes, on their chin and nose, and on each forearm.

Fox squirrels communicate many ways. They use a variety of sounds, including barks, chatters, distress screams, and high-pitched whines. They use scent marks. They also communicate through behavior. For example, they will threaten one another by standing upright with their tail over their back and flicking it.

What do they eat?

Fox squirrels are omnivores, eating everything from plant matter to insects, birds, and carrion. Their diet depends on what is available in the area in which they live. Fox squirrels mainly eat the nuts, flowers, and buds of oak trees and walnut, hickory, and pecan trees. They also eat fruits, seeds, and buds of maple trees, mulberry, hackberry, elms, buckeyes, horse chestnuts, wild cherries, dogwoods, hawthorn, hazelnut, ginkgo, and pine seeds. They eat edible varieties of fungus when they are available. They will eat bird eggs and nestlings, bones, and other small animals or animal remains as they find them. Squirrels are scatterhoarders, which means that they hide small amounts of food in various locations and go back to find it later. They find them later by remembering where they put them and by smelling for the food. They use their strong incisors to chew through the husks of the different kinds of seeds they eat. In the fall of each year fox squirrels begin eating much more than they need so that they can accumulate a large store of body fat to help them get through the winter. Fox squirrels can get some of the water they need from eating moist foods, but generally need to have standing water for drinking. They might find small pools of water that collect after rains in the holes and nooks of large trees. Female fox squirrels need foods with extra protein and calcium, such as bones, meat, and nuts, when they are pregnant and nursing their young.

  • Animal Foods
  • birds
  • mammals
  • eggs
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • Other Foods
  • fungus

What eats them and how do they avoid being eaten?

Fox squirrels are preyed on mainly by large hawks and owls. Young squirrels may also be taken by snakes. Fox squirrels take advantage of their agility and maneuverability in the trees to escape most predators. They emit alarm calls that alert other squirrels when they see a predator.

What roles do they have in the ecosystem?

Because squirrels eat so many tree seeds, they play a significant role in shaping the composition of forests. Together with other seed-eating animals, they may eat almost all of the tree seeds produced in some years. When squirrels bury seeds and forget them, these seeds are likely to sprout where they were placed. Because of this, squirrels promote the growth of certain kinds of trees. Fox squirrels are also important prey items for small predators because they are so abundant.

  • Ecosystem Impact
  • disperses seeds

Do they cause problems?

Some people think squirrels are a nuisance because they raid bird feeders and gardens. They sometimes damage corn crops. They often use electrical lines as routes of travel, and this can cause power outages.

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

Fox squirrels are hunted for food and for their fur, even though the fur is not very valuable. In addition, fox squirrels are important tree seed dispersers.

  • Ways that people benefit from these animals:
  • body parts are source of valuable material

Are they endangered?

Several subspecies of fox squirrels in the eastern United States are endangered due to overhunting and destruction of forests.

Contributors

Bridget Fahey (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that generate their own body heat through metabolic processes.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Koprowski, J. L. Sciurus niger. Mammalian species No. 479: 1-9.

Nowak, R.M. Walker's Mammals of the World, 5th Edition. Johns Hopkins University Press.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 19, 2014 at http://www.biokids.umich.edu/accounts/Sciurus_niger/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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