dcsimg

Lifespan, longevity, and ageing

provided by AnAge articles
Maximum longevity: 16 years (captivity) Observations: One wild born specimen was about 16 years of age when it died in captivity (Richard Weigl 2005).
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Behavior

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Fox squirrels have excellent vision, even in dim light. They have well-developed senses of hearing and smell. Scent marking is used to communicate among fox squirrels. They use a variety of sounds to communicate, including barks, chatters, distress screams, and high-pitched whines during mating. Fox squirrels will threaten one another by standing upright with their tail over their back and flicking it. Fox squirrels also have several sets of vibrissae, 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.

Perception Channels: tactile ; chemical

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Conservation Status

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Many subspecies of fox squirrels are endangered due to overhunting and destruction of mature forests.

US Federal List: endangered; no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Benefits

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Squirrels are often considered a nuisance species due to their raiding of bird feeders and gardens. They are also responsible for some damage to corn crops. They often use electrical lines as routes of travel, and this can cause power outages.

Negative Impacts: crop pest

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Benefits

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Squirrels are be hunted as a food source and for their fur, although the fur is not very valuable. In addition, fox squirrels are important agents of seed dispersal and can aid in succession by burying forest nuts. May play some role in the dispersal of mycorrhizal fungi.

Positive Impacts: body parts are source of valuable material

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Associations

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Because squirrels prey so heavily on the seeds of trees they play a significant role in shaping the composition of forests. They may eat (along with other seed-eating animals) almost all of the tree seeds that trees produce in some years. When squirrels bury seeds and forget them, these seeds are likely to sprout where they were placed. Squirrels, therefore, act to promote the growth of certain kinds of trees. Fox squirrels are also important prey items for small predators because of their abundance in the environment.

Ecosystem Impact: disperses seeds

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Trophic Strategy

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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.

Animal Foods: birds; mammals; eggs; carrion ; insects; terrestrial non-insect arthropods

Plant Foods: leaves; seeds, grains, and nuts; fruit

Other Foods: fungus

Primary Diet: omnivore

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Distribution

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Fox squirrels are found throughout the eastern and central United States, south into northern Mexico, and north into Canada. They have been introduced into urban areas in western North America as well.

Biogeographic Regions: nearctic (Native )

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Habitat

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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.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: urban ; suburban ; riparian

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Life Expectancy

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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.

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Morphology

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Fox squirrels are a medium-sized tree squirrel with no sexual dimorphism. The dorsal pelage is buff to orange and the venter is rufous. Some varieties in the southeastern United States are black. These squirrels have 8 mammae. Tail is well furred. Ear tufts often develop in winter.

Adaptations for climbing include sharp recurved claws, well developed extensors of digits and flexors of forearms, and abdominal musculature.

Range mass: 696.0 to 1233.0 g.

Average mass: 800.0 g.

Range length: 454.0 to 698.0 mm.

Average length: 595.0 mm.

Sexual Dimorphism: sexes alike

Other Physical Features: endothermic ; bilateral symmetry

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Associations

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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.

Known Predators:

  • hawks (Accipitridae)
  • owls (Strigiformes)
  • snakes (Serpentes)
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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Reproduction

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

Mating System: polygynandrous (promiscuous)

Fox squirrels can mate any time of year; this behavior peaks in December and June. Males follow females prior to estrus, smelling the perineal region. Males aggregate in the home range of a female when she begins estrus. Dominance hierarchies form among the males to determine mating privilege. Copulation lasts less than thirty seconds, and females can mate with several males. A copulatory plug forms after mating. Gestation lasts 44-45 days. Average litter size is 2-3, but litters range between 1 and 7. Young are born naked, weighing between 13-18 g. Eyes open at week 5, and young are weaned at week 8. Sexual maturity is attained at 8 months for females, 10-11 months for males. Females can produce 2 litters in a year, although 1 is the norm.

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 gestation period: 44.0 days.

Average time to independence: 3 months.

Average age at sexual or reproductive maturity (female): 1 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous

Average birth mass: 15 g.

Average gestation period: 44 days.

Average number of offspring: 3.

Average age at sexual or reproductive maturity (male)
Sex: male:
353 days.

Average age at sexual or reproductive maturity (female)
Sex: female:
353 days.

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 disperse away from their mothers range in the fall of their first year. Male fox squirrels disperse farther and may die more as a result.

Parental Investment: altricial

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Fahey, B. 2001. "Sciurus niger" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_niger.html
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Bridget Fahey, University of Michigan-Ann Arbor
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Associated Plant Communities

provided by Fire Effects Information System Animals
More info for the terms: hardwood, swamp, woodland

Eastern fox squirrels inhabit a variety of open hardwood, hardwood-pine, and
swamp communities depending on geographic location. The Delmarva fox
squirrel in Maryland prefers mature stands of hardwoods such as oaks
(Quercus spp.), hickories (Carya spp.), walnuts (Juglans spp.), and
beech (Fagus spp.) that are interspersed with mature loblolly pine
(Pinus taeda). Delmarva fox squirrels are also found in deciduous
swamps close to pine woodlands [2,5,9]. In southern Florida, fox
squirrels occupy pine hammocks and range into mangrove (Rhizophora spp.)
and cypress (Cupressus spp.) stands. In coastal regions of northern
Florida, Georgia, and the Carolinas, eastern fox squirrels are most often found
in longleaf pine (Pinus palustris)/turkey oak (Quercus laevis) habitats
[5]. In Alabama, eastern fox squirrels occur along watercourses, on the shores
of bayous and in deep bald cypress (Taxodium distichum) swamps, and in
upland dry pine stands [5].

In eastern Texas, eastern fox squirrels inhabit oak-hickory ridges. Farther
west, they occupy both timbered river bottoms and oak ridges. In the
central portions of Oklahoma and Iowa, easter4n fox squirrels are most abundant
in the transition belt between prairie and oak woodland. Here, eastern fox
squirrels also occupy upland hardwood forests, dense timber along
streams and rivers, and open pecan (Carya pecan) orchards [5]. Primary
eastern fox squirrel habitat in Wisconsin is oak-hickory woodlots with oak,
swamp hardwoods, and mixed upland hardwoods [5].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Common Names

provided by Fire Effects Information System Animals
eastern fox squirrel
stump-eared squirrel
cat squirrel
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Conservation Status

provided by Fire Effects Information System Animals
Information on state- and province-level protection status of animals in the
United States and Canada is available at NatureServe, although recent
changes in status may not be included.
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Cover Requirements

provided by Fire Effects Information System Animals
More info for the terms: cover, forest, litter, tree

Eastern fox squirrels use leaf nests or tree cavities for shelter and litter
rearing [1]. Forest stands dominated by mature to over mature trees
provide cavities and a sufficient number of sites for leaf nests to meet
the cover requirements. Overstory trees with an average d.b.h. of 15
inches (38.1 cm) or more generally provide adequate cover and
reproductive habitat. Optimum tree canopy closure for eastern fox squirrels is
from 20 to 60 percent. Optimum conditions understory closure occur when
the shrub-crown closure is 30 percent or less [1].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Distribution

provided by Fire Effects Information System Animals
Eastern fox squirrels occur along the Atlantic and Gulf coastal plains
from the Delmarva Peninsula in Maryland south to central Florida and
west to the Mississippi River floodplain [23]. Delmarva fox squirrels
occur in only four Eastern Shore counties in Maryland and one location
in Accomac County, Virginia. This subspecies was formerly found in
southeastern Pennsylvania, Delaware, New Jersey, and probably the
Virginia portion of the Delmarva Peninsula [2]. S. n. ssp. avicennia
occurs in southern Florida; S. n. ssp. subauratus occurs on the
Mississippi River floodplain [23].

The range of mid-western fox squirrels extends from the valleys of
south-central Pennsylvania south through the Appalachian Mountains and
the uplands of the Gulf States and west to the prairies and more
recently to the front range of the Rocky Mountains [23]. Mid-western fox
squirrels have also extended their range into northern Michigan and
westward to North Dakota, eastern Colorado, and Texas. In northern
Mexico, fox squirrels occur in the states of Coahuila, Nuevo Leon, and
Tamaulipas [16].

Eastern fox squirrels have been introduced into many portions of the West.
Introduced populations exist in California, Oregon, Washington, Idaho,
and Montana [1,5,12,16].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Food Habits

provided by Fire Effects Information System Animals
More info for the terms: fruit, mast, milk stage, swamp, tree

Food habits of eastern fox squirrels depend largely on geographic location [5].
In general, eastern fox squirrel foods include mast, tree buds, insects, tubers,
bulbs, roots, bird eggs, seeds of pines and spring-fruiting trees, and
fungi. Agricultural crops such as corn, soybeans, oats, wheat, and
fruit are also eaten [1,5,16,23]. Mast eaten by eastern fox squirrels
commonly includes turkey oak, southern red oak (Q. falcata), blackjack
oak (Q. marilandica), bluejack oak (Q. incana), post oak (Q.
stellata), and live oak (Q. virginiana) [23].

In Illinois, eastern fox squirrels rely heavily on hickories from late August
through September. Pecans, black walnuts (Juglans nigra), osage orange
(Maclura pomifera) fruits, and corn are also important fall foods. In
early spring, elm buds and seeds are the most important food. In May
and June, mulberries (Morus spp.) are heavily utilized. By early
summer, corn in the milk stage becomes a primary food [5].

During the winter in Kansas, osage orange is a staple item supplemented
with seeds of the Kentucky coffee tree (Gymnocladus dioicus) and honey
locust (Gleditsia triacanthus), corn, wheat, eastern cottonwood (Populus
deltoides var. deltoides) bark, ash seeds, and eastern redcedar
(Juniperus virginianus) berries. In the spring, eastern fox squirrels feed
primarily on buds of elm, maple, and oaks but also on newly sprouting
leaves and insect larvae [5].

Eastern fox squirrels in Ohio prefer hickory nuts, acorns, corn, and black
walnuts. The squirrels are absent where two or more of these mast trees
are missing. Eastern fox squirrels also eat buckeyes, seeds and buds of maple
and elm, hazelnuts (Corylus spp.), blackberries (Rubus spp.), and tree
bark. In March, they feed mainly on buds and seeds of elm, maple, and
willow. In Ohio, eastern fox squirrels have the following order of food
preference: white oak (Quercus alba) acorns, black oak (Q. velutina)
acorns, red oak (Q. rubra) acorns, walnuts, and corn [5].

In eastern Texas, eastern fox squirrels prefer the acorns of bluejack oak,
southern red oak (Q. falcata), and overcup oak (Q. lyrata). The least
preferred foods are acorns of swamp chestnut oak (Q. michauxii) and
overcup oak. In California, eastern fox squirrels feed on English walnuts (J.
regia), oranges, avocados, strawberries, and tomatoes. In midwinter,
they feed on eucalyptus seeds [5].

In Michigan, eastern fox squirrels feed on a variety of foods throughout the
year. Spring foods are mainly tree buds and flowers, insects, bird
eggs, and seeds of red maple (Acer rubrum), silver maple (A.
saccharinum), and elms. Summer foods include a variety of berries, plum
and cherry pits, fruits of basswood (Tilia americana), fruits of box
elder (Acer negundo), black oak acorns, hickory nuts, seeds of sugar (A.
saccharum) and black maple (A. nigrum), grains, insects, and unripe
corn. Fall foods consist mainly of acorns, hickory nuts, beechnuts,
walnuts, butternuts (J. cinerea), and hazelnuts. Caches of acorns and
hickory nuts are heavily used in winter [5].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat-related Fire Effects

provided by Fire Effects Information System Animals
More info for the terms: cone, cover, duff, forest, ground fire, hardwood, mast

Fire often has a positive effect on eastern fox squirrel habitat. Fire
maintains the pine-oak habitat preferred by eastern fox squirrels and has a
direct effect on eastern fox squirrel foods. Under presettlement conditions
longleaf pine savannas (preferred eastern fox squirrel habitat) may have burned
at average intervals of 3 to 5 years, usually between April and October.
The open stands produced by fire result in better pine cone and mast
production. Pines and oaks growing in the open receive more light,
maintain more branches at lower levels, and produce heavier crops of
cones and nuts [23]. Additionally, nutrient availability and the
enhanced vigor of burned pine forest are associated with larger crops of
fungi. which are also important eastern fox squirrel foods [23]. A lush, grassy
understory maintained by fire is important as protective cover [15].

Fire has probably been a determining factor in the niche separation
between gray and eastern fox squirrels on the Coastal Plain. Both exist in
mixed pine-oak forests and feed heavily on acorns, but the more
competitive gray squirrel dominates where the overlap of oak crowns
allows tree-to-tree travel throughout the canopy. Eastern fox squirrels are
more abundant where patches of oaks comprise less than 30 percent of
pine-hardwood stands and do best in fire-type pine forests with
scattered hardwood inclusions [15]. Fire could be a deciding factor in
determining the availability of suitable habitat and resources for one or
the other species [23].

Fire can also have a negative effect on eastern fox squirrel habitat.
Low-intensity ground fire may destroy acorns in the forest duff [15].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Cover Types

provided by Fire Effects Information System Animals
More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the terms: hardwood, swamp

14 Northern pin oak
16 Aspen
17 Pin cherry
18 Paper birch
19 Gray birch - red maple
20 White pine - northern red oak - red maple
24 Hemlock - yellow birch
25 Sugar maple - beech - yellow birch
26 Sugar maple - basswood
27 Sugar maple
28 Black cherry - maple
39 Black ash - American elm - red maple
40 Post oak - blackjack oak
42 Bur oak
43 Bear oak
44 Chestnut oak
51 White pine - chestnut oak
52 White oak - black oak - northern red oak
53 White oak
55 Northern red oak
59 Yellow-poplar - white oak - northern red oak
60 Beech - sugar maple
61 River birch - sycamore
62 Silver maple - American elm
65 Pin oak - sweetgum
71 Longleaf pine - scrub oak
70 Longleaf pine
76 Shortleaf pine - oak
78 Virginia pine - oak
80 Loblolly pine - shortleaf pine
81 Loblolly pine
82 Loblolly pine - hardwood
85 Slash pine - hardwood
87 Sweet gum - yellow-poplar
88 Willow oak - water oak - diamondleaf oak
89 Live oak
91 Swamp chestnut oak - cherrybark oak
92 Sweetgum - willow oak
93 Sugarberry - American elm - green ash
94 Sycamore - sweetgum - American elm
95 Black willow
96 Overcup oak - water hickory
100 Pondcypress
101 Baldcypress
105 Tropical hardwoods
108 Red maple
109 Hawthorn
110 Black oak
203 Balsam poplar
217 Aspen
221 Red alder
222 Black cottonwood - willow
233 Oregon white oak
235 Cottonwood - willow
236 Bur oak
241 Western live oak
246 California black oak
249 Canyon live oak
250 Blue oak - Digger pine
252 Paper birch
255 California coast live oak
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Ecosystem

provided by Fire Effects Information System Animals
More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES10 White-red-jack pine
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES28 Western hardwoods
FRES41 Wet grasslands
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Plant Associations

provided by Fire Effects Information System Animals
More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

K025 Alder - ash forest
K026 Oregon oakwoods
K030 California oakwoods
K080 Marl - everglades
K090 Live oak - sea oats
K091 Cypress savanna
K092 Everglades
K098 Northern floodplain forest
K099 Maple - basswood forest
K100 Oak - hickory forest
K101 Elm - ash forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K105 Mangrove
K106 Northern hardwoods
K108 Northern hardwoods - spruce forest
K110 Northeastern oak - pine forest
K111 Oak - hickory - pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
K115 Sand pine scrub
K116 Subtropical pine forest
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Management Considerations

provided by Fire Effects Information System Animals
More info for the terms: forest, natural

The range of eastern fox squirrels in the the eastern states has been greatly
reduced in the past 100 years [5]. Habitat reduction is one cause. The
Coastal Plain of North Carolina and other southern states is undergoing
rapid deforestation and forest modification due to accelerated
residential and agricultural development, and intensive management
techniques in commercial forests [23]. Another major cause of eastern fox
squirrel population decline is mange mite (Cnemidoptes sp.) along with
severe winter weather [5].

One of the primary reasons for the decline of the endangered Delmarva
fox squirrel is timber harvest. As large trees are removed so are much
of the areas that provide the Delmarva fox squirrel with an open
understory habitat. With loss of habitat, this subspecies is forced to
compete with gray squirrels (Sciurus carolinensis) for food and nesting
resources. Logging practices that include harvesting all the big
hardwoods and replacing them with stands of pure loblolly pine are also
detrimental to Delmarva fox squirrels, since stands of pure species do
not provide good fox squirrel habitat [19].

In addition, the effects of timber harvest prohibit eastern fox squirrel habitat
from developing. At the point where trees become of a salable size,
they are not large enough to provide sufficient food and den sites for
squirrel utilization [19].

Habitat can be improved for eastern fox squirrels by selective cutting to
encourage nut-bearing trees and other food species; planting corn and
soybeans; leaving overmature and large-crowned trees; and opening up the
forest understory by burning or light grazing [5]. Maintenance of
wooded fencerows and breaking up forests into small, 5- to 10-acre (2-4
ha) woodlots of irregular shapes also would promote eastern fox squirrel
populations [5].

In cut-over areas where all den trees have been removed, den boxes can
be used to supplement natural den trees. Den boxes are very useful on
prairies and young woodlots where there is a shortage of natural
cavities [20]. Use of artificial den boxes is an important part of the
recovery plan for the Delmarva eastern fox squirrel [9].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Predators

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More info for the term: natural

Relatively few natural predators can regularly capture adult eastern fox
squirrels. Of these predators, most only take eastern fox squirrels
opportunistically [23]. Eastern fox squirrel predators include: bobcats (Felis
rufus), foxes (Vulpes spp. and Urocyon spp.), red-tailed hawks (Buteo
jamaicensis), red-shouldered hawks (Buteo lineatus), great-horned owls
(Bubo virginianus), barred owls (Strix varia), and dogs (Canidae)
[3,5,23]. Nestlings and young eastern fox squirrels are particularly vulnerable
to climbing predators such as raccoons (Procyon lotor), opossums
(Didelphis virginiana), rat snakes (Elaphe obsoleta), and pine snakes
(Pituophis melanoleucus) [23]. In those states where eastern fox squirrels are
not protected, they are considered a game animal [5,23]. Eastern fox squirrels
are hunted more for trophy than for food [23]. Overharvest by hunting
has been reported from small woodlots and public shooting areas in Ohio,
Michigan, and Indiana [5].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Preferred Habitat

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More info for the terms: forest, natural, tree, woodland

Eastern fox squirrels are most abundant in open forest stands with little
understory vegetation; they are not found in stands with dense
undergrowth. Ideal habitat is small stands of large trees interspersed
with agricultural land [1,9]. The size and spacing of pines and oaks
are among the important features of eastern fox squirrel habitat. The actual
species of pines and oaks themselves may not always be a major
consideration in defining eastern fox squirrel habitat [23]. Eastern fox squirrels are
often observed foraging on the ground several hundred meters from the
nearest woodlot. Eastern fox squirrels also commonly occupy forest edge habitat
[6].

In general, the woodland habitats occupied by the Delmarva fox squirrel
are similar to those occupied by other subspecies of eastern fox squirrels [6].
The Delmarva fox squirrel habitat consists primarily of relatively small
stands of mature mixed hardwoods and pines that have relatively closed
canopies, open understories, and a high proportion of forest edge.
Occupied areas include both groves of trees along streams and bays and
small woodlots near agricultural fields. In some areas, particularly in
southern Dorchester County, Maryland, occupied habitat includes areas
dominated by mature loblolly pine located adjacent to marshes and tidal
streams.

Nest - Eastern fox squirrels have two types of shelters: leaf nests and tree
dens. They may have two tree cavity homes or a tree cavity and a leaf
nest. Tree dens are preferred over leaf nests during the winter and for
raising young. When den trees are scarce, leaf nests are used
year-round [3,16]. Leaf nests are built during the summer months in
forks of deciduous trees about 30 feet (9 m) above the ground. Eastern fox
squirrels use natural cavities and crotches (forked branches of a tree)
as tree dens [3]. Den trees in Ohio had an average d.b.h. of 21.2
inches (53 cm) and were an average of 58.6 yards (52.7 m) from the
nearest woodland border. Eighty-eight percent of den trees in eastern
Texas had an average d.b.h. of 12 inches (30 cm) or more [1]. Dens are
usually 6 inches (15.2 cm) wide and 14 to 16 (35-41 cm) inches deep.
Den openings are generally circular and about 2.9 to 3.7 inches (7.3-9.4
cm). Eastern fox squirrels may make their own den in a hollow tree by cutting
through the interior; however, they generally use natural cavities or
cavities created by northern flickers (Colaptes auratus) or redheaded
woodpeckers (Melanerpes erythrocephalus). Crow nests have also been
used by eastern fox squirrels [16].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Regional Distribution in the Western United States

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More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
8 Northern Rocky Mountains
11 Southern Rocky Mountains
13 Rocky Mountain Piedmont
14 Great Plains
16 Upper Missouri Basin and Broken Lands
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Taxonomy

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The currently recognized scientific name for the eastern fox squirrel is Sciurus
niger L. Ten subspecies are recognized: four eastern, four mid-western,
and two isolated subspecies [5,23].

Eastern fox squirrels are very large (2.4 to 3.2 pounds [900-1200 g]);
gray, agouti, or black; and often have black markings on the head and
white nose, ears, and paws [23]. Eastern fox squirrel subspecies are
listed below:

S. niger ssp. cinerea (Delmarva fox squirrel)
S. niger ssp. niger
S. niger ssp. shermani (Sherman's fox squirrel)
S. niger ssp. bachmani

Mid-western fox squirrels are smaller (1.6 to 2.4 pounds [600-900 g]) and
reddish. Subspecies are as follows [23]:

S. niger ssp. rufiventer
S. niger ssp. vulpinus
S. niger ssp. ludovicianus
S. niger ssp. limitis

A third group is composed of two small, variably colored, and isolated
subspecies: S. n. ssp. avicennia Howell (Big Cypress fox squirrel) and
S. n. ssp. ubauratus [23,24].

While eastern and mid-western subspecies are now widely separated in the
Atlantic States, considerable gene flow is possible in the Gulf Region
[23].

Where appropriate, the Delmarva fox squirrel will be highlighted
in this report.
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Timing of Major Life History Events

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More info for the terms: litter, tree

Breeding season - Female eastern fox squirrels come into estrus in mid-December
or early January and again in June. Eastern fox squirrels normally produce two
litters a year [3,5]. However, yearling females may produce only one
litter, and poor food conditions may prevent some adult females from
breeding [5].

Breeding age - Females become sexually mature at 10 to 11 months of age.
They usually produce their first litter when they are 1 year old [5].

Gestation/litter size - The gestation period of eastern fox squirrels is 44 to
45 days. Earliest litters appear in late January; most births occur in
mid-March and July [5]. The average litter size is three, but litter
size can vary according to season and food conditions [5].

Development of young - Tree squirrels develop slowly compared to other
rodents. Eyes open when eastern fox squirrels are 4 to 5 weeks old, and ears
open at 6 weeks. Eastern fox squirrels are weaned between 8 and 10 weeks but
may not be self-supporting until 12 weeks [5,16]. Juveniles usually
disperse in September or October, but they may den together or with
their mother the first winter [3,22].

Longevity - Eastern fox squirrels generally live up to 6 years in the wild but
have survived 13 years in captivity [5,16].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

U.S. Federal Legal Status

provided by Fire Effects Information System Animals
The Delmarva fox squirrel is Endangered [21].
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Use of Fire in Population Management

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More info for the terms: fire management, fire regime

Prescribed fire can be used to maintain eastern fox squirrel habitat.
Prescribed burning at 2- to 5-year intervals can be beneficial to eastern fox
squirrels by maintaining an open understory and better foraging habitat
[11]. According to Humphrey [24], ground fires are valuable in
maintaining habitats of Big Cypress fox squirrels. In the habitat of
this subspecies, future fire management plans call for an increase in
prescribed burning to 50,000 acres a year. Pinelands are expected to be
burned on a 5- to 7-year rotation [24].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".
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Tesky, Julie L. 1993. Sciurus niger. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Fox squirrel

provided by wikipedia EN

The fox squirrel (Sciurus niger), also known as the eastern fox squirrel or Bryant's fox squirrel,[2] is the largest species of tree squirrel native to North America. Despite the differences in size and coloration, it is sometimes mistaken for American red squirrels or eastern gray squirrels in areas where the species co-exist.[3]

Description

The squirrel's total length measures 20 to 30 in (50.8 to 76.2 cm), with a body length of 10 to 15 in (25.4 to 38.1 cm) and a similar tail length. They range in weight from 1.0 to 2.5 pounds (453.6 to 1,134.0 g).[4] There is no sexual dimorphism in size or appearance. Individuals tend to be smaller in the west. There are three distinct geographical phases in coloration: In most areas the animal's upper body is brown-grey to brown-yellow with a typically brownish-orange underside, while in eastern regions such as the Appalachians there are more strikingly-patterned dark brown and black squirrels with white bands on the face and tail. In the south are isolated communities with uniform black coats. To help with climbing, the squirrels have sharp claws, developed extensors of digits and flexors of forearms, and abdominal musculature.[5] Fox squirrels have excellent vision and well-developed senses of hearing and smell. They use scent marking to communicate with other fox squirrels.[5] "Fox squirrels also have several sets of vibrissae, 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."[5] The dental formula of S. niger is 1.0.1.31.0.1.3 × 2 = 20.[6]

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Fox squirrel foraging in the grass in Indianapolis, Indiana

Distribution

The fox squirrel's natural range extends through most of the eastern United States, north into the southern prairie provinces of Canada, and west to the Dakotas, Colorado, and Texas. They are absent (except for vagrants) in New England, New Jersey, most of New York, northern and eastern Pennsylvania, Ontario, Quebec, and the Atlantic provinces of Canada. They have been introduced to both northern and southern California,[7] Oregon,[8] Idaho,[9] Montana,[9] Washington,[9] and New Mexico,[9] as well as Ontario and British Columbia in Canada. While very versatile in their habitat choices, fox squirrels are most often found in forest patches of 40 hectares or less with an open understory, or in urban neighborhoods with trees. They thrive best among oak, hickory, walnut, pecan and pine trees, storing their nuts for winter. Western range extensions in Great Plains regions such as Kansas are associated with riverine corridors of cottonwood. A subspecies native to several eastern US states is the Delmarva fox squirrel (S. n. cinereus).[4]

Invasiveness

In Europe, Sciurus niger is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list).[10] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.[11]

Habitat

Fox squirrels are most abundant in open forest stands with little understory vegetation; they are not found in stands with dense undergrowth. Ideal habitat is small stands of large trees interspersed with agricultural land.[12] The size and spacing of pines and oaks are among the important features of fox squirrel habitat. The actual species of pines and oaks themselves may not always be a major consideration in defining fox squirrel habitat.[4] Fox squirrels are often observed foraging on the ground several hundred meters from the nearest woodlot. Fox squirrels also commonly occupy forest edge habitat.[13]

Fox squirrels have two types of shelters: leaf nests (dreys) and tree dens. They may have two tree cavity homes or a tree cavity and a leaf nest. Tree dens are preferred over leaf nests during the winter and for raising young. When den trees are scarce, leaf nests are used year-round.[14][15] Leaf nests are built during the summer months in forks of deciduous trees about 30 feet (9 m) above the ground. Fox squirrels use natural cavities and crotches (forked branches of a tree) as tree dens.[14] Den trees in Ohio had an average diameter at breast height (d.b.h.) of 21 inches (53 cm) and were an average of 58.6 yards (53.6 m) from the nearest woodland border. About 88% of den trees in eastern Texas had an average d.b.h. of 12 inches (30 cm) or more.[12] Dens are usually 6 inches (15 cm) wide and 14–16 inches (36–41 cm) inches deep. Den openings are generally circular and about 2.9 to 3.7 inches (7.4 to 9.4 cm). Fox squirrels may make their own den in a hollow tree by cutting through the interior; however, they generally use natural cavities or cavities created by northern flickers (Colaptes auratus) or red-headed woodpeckers (Melanerpes erythrocephalus). Crow nests have also been used by fox squirrels.[15]

Fox squirrels use leaf nests or tree cavities for shelter and litter rearing.[12] Forest stands dominated by mature to over mature trees provide cavities and a sufficient number of sites for leaf nests to meet the cover requirements. Overstory trees with an average d.b.h. of 15 inches (38 cm) or more generally provide adequate cover and reproductive habitat. Optimum tree canopy closure for fox squirrels is from 20% to 60%. Optimum conditions of understory closure occur when the shrub-crown closure is 30% or less.[12]

Fox squirrels are tolerant of human proximity, and even thrive in crowded urban and suburban environments. They exploit human habitations for sources of food and nesting sites, being as happy nesting in an attic as they are in a hollow tree.[16]

Diet

 src=
Backyard fox squirrel searching for a location to bury its acorn, in Berkeley, California
Manipulation of food items by paws and head
 src=
Eating a Santa Rosa plum in Fullerton, California

Food habits of fox squirrels depend largely on geographic location.[17] In general, fox squirrel foods include mast, tree buds, insects, tubers, bulbs, roots, bird eggs, seeds of pines and spring-fruiting trees, and fungi. Agricultural crops such as corn, soybeans, oats, wheat, and fruit are also eaten.[4][12][15][17] Mast eaten by fox squirrels commonly includes turkey oak (Quercus laevis), southern red oak (Quercus falcata), blackjack oak (Quercus marilandica), bluejack oak (Quercus incana), post oak (Quercus stellata), and live oak (Quercus virginiana).[4]

In Illinois, fox squirrels rely heavily on hickories from late August through September. Pecans, black walnuts (Juglans nigra), osage orange (Maclura pomifera) fruits, and corn are also important fall foods. In early spring, elm buds and seeds are the most important food. In May and June, mulberries (Morus spp.) are heavily used. By early summer, corn in the milk stage becomes a primary food.[17]

During the winter in Kansas, osage orange is a staple item supplemented with seeds of the Kentucky coffee tree (Gymnocladus dioicus) and honey locust (Gleditsia triacanthos), corn, wheat, eastern cottonwood (Populus deltoides var. deltoides) bark, ash seeds, and eastern red cedar (Juniperus virginiana) berries. In the spring, fox squirrels feed primarily on buds of elm, maple, and oaks but also on newly sprouting leaves and insect larvae.[17]

Fox squirrels in Ohio prefer hickory nuts, acorns, corn, and black walnuts. The squirrels are absent where two or more of these mast trees are missing. Fox squirrels also eat buckeyes, seeds and buds of maple and elm, hazelnuts (Corylus spp.), blackberries (Rubus spp.), and tree bark. In March, they feed mainly on buds and seeds of elm, maple, and willow. In Ohio, eastern fox squirrels have the following order of food preference: white oak (Quercus alba) acorns, black oak (Quercus velutina) acorns, red oak (Quercus rubra) acorns, walnuts, and corn.[17]

In eastern Texas, fox squirrels prefer the acorns of bluejack oak, pecans, southern red oak (Q. falcata), and overcup oak (Q. lyrata). The least preferred foods are acorns of swamp chestnut oak (Q. michauxii) and overcup oak. In California, fox squirrels feed on English walnuts (J. regia), oranges, avocados, strawberries, and tomatoes. In midwinter, they feed on eucalyptus seeds.[17]

In Michigan, fox squirrels feed on a variety of foods throughout the year. Spring foods are mainly tree buds and flowers, insects, bird eggs, and seeds of red maple (Acer rubrum), silver maple (Acer saccharinum), and elms. Summer foods include a variety of berries, plum and cherry pits, fruits of basswood (Tilia americana), fruits of box elder (Acer negundo), black oak acorns, hickory nuts, seeds of sugar (Acer saccharum) and black maple (Acer nigrum), grains, insects, and unripe corn. Fall foods consist mainly of acorns, hickory nuts, beechnuts, walnuts, butternuts (Juglans cinerea), and hazelnuts. Caches of acorns and hickory nuts are heavily used in winter.[17]

Behavior

 src=
Fox squirrel eating an acorn
 src=
Fox squirrel on Pebble Beach, California, USA.

Fox squirrels are strictly diurnal, non-territorial, and spend more of their time on the ground than most other tree squirrels. They are still, however, agile climbers. They construct two types of homes called "dreys", depending on the season. Summer dreys are often little more than platforms of sticks high in the branches of trees, while winter dens are usually hollowed out of tree trunks by a succession of occupants over as many as 30 years. Cohabitation of these dens is not uncommon, particularly among breeding pairs.

Fox squirrels will form caches by burying food items for later consumption.[18] They like to store foods that are shelled and high in fat, such as acorns and nuts. Shelled foods are favored because they are less likely to spoil than non-shelled foods, and fatty foods are valued for their high energy density.[19][20]

They are not particularly gregarious or playful, in fact they have been described as solitary and asocial creatures, coming together only in breeding season.[21] They have a large vocabulary, consisting most notably of an assortment of clucking and chucking sounds, not unlike some "game" birds, and they warn of approaching threats with distress screams. In the spring and fall, groups of fox squirrels clucking and chucking together can make a small ruckus. They also make high-pitched whines during mating. When threatening another fox squirrel, they will stand upright with their tail over their back and flick it.[5]

They are impressive jumpers, easily spanning fifteen feet in horizontal leaps and free-falling twenty feet or more to a soft landing on a limb or trunk.

Reproduction

 src=
Pup

Female fox squirrels come into estrus in mid-December or early January, then again in June. They normally produce two litters a year; however, yearling females may only produce one.[17] Females become sexually mature at 10 to 11 months of age and usually produce their first litter when they are a year old.[17]

Gestation occurs over a period of 44 to 45 days. Earliest litters appear in late January; most births occur in mid-March and July. The average litter size is three, but can vary according to season and food conditions.[17]

Tree cavities, usually those formed by woodpeckers, are remodeled to winter dens and often serve as nurseries for late winter litters. If existing trees lack cavities, leaf nests known as dreys are built by cutting twigs with leaves and weaving them into warm, waterproof shelters. Similar leafy platforms are built for summer litters and are often referred to as "cooling beds."[22]

Tree squirrels develop slowly compared to other rodents. At birth, the young are blind, without fur and helpless. Eyes open at 4 to 5 weeks of age and ears open at 6 weeks. Eastern fox squirrels are weaned between 12 and 14 weeks but may not be self-supporting until 16 weeks.[15][17] Juveniles usually disperse in September or October, but may den either together or with their mother during their first winter.[14]

Mortality

 src=
Fox squirrel pausing from building its nest in an attic in Berkeley, California.

In captivity, fox squirrels have been known to live 18 years, but in the wild most fox squirrels die before they become adults.[5] Their maximum life expectancy is typically 12.6 years for females and 8.6 years for males. Because of overhunting and the destruction of mature forests, many subspecies of fox squirrel (the Delmarva fox squirrel for example) are endangered.[5] Another major cause of fox squirrel population decline is mange mite (Cnemidoptes sp.) along with severe winter weather.[17]

Relatively few natural predators can regularly capture adult fox squirrels. Of these predators, most only take fox squirrels opportunistically.[4] Predators include: bobcats (Lynx rufus), Canada lynx (Lynx canadensis), foxes (Vulpes vulpes and Urocyon cinereoargenteus), red-tailed hawks (Buteo jamaicensis), red-shouldered hawks (Buteo lineatus), great horned owls (Bubo virginianus), barred owls (Strix varia), and coyotes (Canis latrans). Former predators extirpated from most of the fox squirrel's range included cougars (Puma concolor) and grey wolves (Canis lupus).[4][14][17] Nestlings and young fox squirrels are particularly vulnerable to climbing predators such as raccoons (Procyon lotor), opossums (Didelphis virginiana), rat snakes (Elaphe obsoleta), and pine snakes (Pituophis melanoleucus). In those states where fox squirrels are not protected, they are considered a game animal.[4] Fox squirrels were an important source of meat for European settlers in the 17th and 18th centuries. They are still hunted over most of their range. [4] Overhunting has been reported from small woodlots and public shooting areas in Ohio, Michigan, and Indiana.[17]

See also

References

  1. ^ Thorington, R.W., Jr.; Hoffmann, R.S. (2005). "Sciurus (Sciurus) niger". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: a taxonomic and geographic reference (3rd ed.). The Johns Hopkins University Press. pp. 754–818. ISBN 978-0-8018-8221-0. OCLC 26158608.
  2. ^ a b Linzey, A. V.; Timm, R.; Emmons, L. & Reid, F. (2008). "Sciurus niger". IUCN Red List of Threatened Species. 2008. Retrieved 2009-01-06.old-form url
  3. ^ Graham, Donna. "Fox Squirrel (Sciurus niger)". Northern State University. South Dakota Department of Game, Fish and Parks. Retrieved 2013-12-07.
  4. ^ a b c d e f g h i Van Gelden, Richard George. (1982). Mammals of the National Parks. Baltimore, MD: Johns Hopkins University Press
  5. ^ a b c d e f "Sciurus niger page". University of Michigan Museum of Zoology. Retrieved 2009-04-23.
  6. ^ Koprowski, John L. (1994-12-02). "Sciurus niger". Mammalian Species (479): 1–9. doi:10.2307/3504263. ISSN 0076-3519. JSTOR 3504263..
  7. ^ "Southern California Fox Squirrel Page". www.calstatela.edu. Retrieved 2008-04-25.
  8. ^ "Mammal Species of Oregon – Squirrels". Oregon Dept. of Fish and Wildlife. Retrieved 2014-03-29.
  9. ^ a b c d "TREE SQUIRRELS AS INVASIVE SPECIES: CONSERVATION AND MANAGEMENT IMPLICATIONS" (PDF). www.ag.arizona.edu. Retrieved 2014-10-08.
  10. ^ "List of Invasive Alien Species of Union concern - Environment - European Commission". ec.europa.eu. Retrieved 2021-07-27.
  11. ^ "REGULATION (EU) No 1143/2014 of the European parliament and of the council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species".{{cite web}}: CS1 maint: url-status (link)
  12. ^ a b c d e Allen, A. W. 1982. Habitat suitability index models: fox squirrel. FWS/OBS-82/10.18. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service
  13. ^ Dueser, Raymond D.; Dooley, James L., Jr.; Taylor, Gary J. (1988). Habitat structure, forest composition and landscape dimensions as components of habitat suitability for the Delmarva fox squirrel. In: Management of amphibians, reptiles, and small mammals in North America: Proceedings of the symposium; 1988 July 19–21; Flagstaff, AZ. Gen. Tech. Rep. RM-166. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 414–421
  14. ^ a b c d Banfield, A. W. F. (1974). The mammals of Canada. Toronto, ON: University of Toronto Press.
  15. ^ a b c d MacClintock, Dorcas. (1970). Squirrels of North America. New York: Litton Educational Publishing, Inc.
  16. ^ "Wild Care: Meet the Fox Squirrels".
  17. ^ a b c d e f g h i j k l m n Chapman, Joseph A.; Feldhamer, George A., eds. 1982. Wild mammals of North America. Baltimore, MD: The Johns Hopkins University Press
  18. ^ Koprowski, John L. (1994-12-02). "Sciurus niger". Mammalian Species (479): 1–9. doi:10.2307/3504263. ISSN 0076-3519. JSTOR 3504263.
  19. ^ Preston, Stephanie D.; Jacobs, Lucia F. (2009). "Mechanisms of Cache Decision Making in Fox Squirrels (Sciurus niger)". Journal of Mammalogy. 90 (4): 787–795. doi:10.1644/08-mamm-a-254.1. JSTOR 27755064.
  20. ^ Kotler, Burt P.; Brown, Joel S.; Hickey, Michael (1999). "Food Storability and the Foraging Behavior of Fox Squirrels (Sciurus niger)". The American Midland Naturalist. 142 (1): 77–86. doi:10.1674/0003-0031(1999)142[0077:fsatfb]2.0.co;2. JSTOR 2426894.
  21. ^ Carraway, Mike. "Fox Squirrel, North Carolina Wildlife Profiles" (PDF). The North Carolina Wildlife Resources Commission. n.p. Retrieved 2013-12-07.
  22. ^ "DNR: Fox Squirrel". www.in.gov. Retrieved 2015-09-29.

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Fox squirrel: Brief Summary

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The fox squirrel (Sciurus niger), also known as the eastern fox squirrel or Bryant's fox squirrel, is the largest species of tree squirrel native to North America. Despite the differences in size and coloration, it is sometimes mistaken for American red squirrels or eastern gray squirrels in areas where the species co-exist.

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