Download Sciurus carolinensis, Eastern Gray Squirrel

The IUCN Red List of Threatened Species™
ISSN 2307-8235 (online)
IUCN 2008: T42462A10699433
Sciurus carolinensis, Eastern Gray Squirrel
Assessment by: Linzey, A.V., Koprowski, J. & NatureServe (Hammerson, G.)
View on www.iucnredlist.org
Citation: Linzey, A.V., Koprowski, J. & NatureServe (Hammerson, G.). 2008. Sciurus carolinensis. The
IUCN Red List of Threatened Species 2008: e.T42462A10699433.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
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THE IUCN RED LIST OF THREATENED SPECIES™
Taxonomy
Kingdom
Phylum
Class
Order
Family
Animalia
Chordata
Mammalia
Rodentia
Sciuridae
Taxon Name: Sciurus carolinensis Gmelin, 1788
Common Name(s):
• English:
Eastern Gray Squirrel, Gray Squirrel, Grey Squirrel
Assessment Information
Red List Category & Criteria:
Least Concern ver 3.1
Year Published:
2008
Date Assessed:
June 30, 2008
Justification:
Listed as Least Concern because of its wide distribution, large population, occurrence in a number of
protected areas, no major threats, and it is tolerant to habitat disturbance and its population is
increasing.
Previously Published Red List Assessments
1996 – Lower Risk/least concern (LR/lc)
Geographic Range
Range Description:
This species is found in the eastern United States and adjacent southern Canada; southern Quebec to
Manitoba, south to eastern Texas and Florida. Its range has been extended through introductions into
Quebec, Ontario, New Brunswick, Manitoba, Saskatchewan, British Columbia, Nova Scotia, California,
Oregon, Washington, and Montana (Teaford 1986, Koprowski 1994). It is also introduced in the British
Isles, Italy, South Africa, and Australia (extirpated by 1973), but these introduced ranges are not
included in the map here (see Koprowski 1994).
Country Occurrence:
Native: Canada; United States
Introduced: Italy; South Africa; United Kingdom
© The IUCN Red List of Threatened Species: Sciurus carolinensis – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
1
Distribution Map
© The IUCN Red List of Threatened Species: Sciurus carolinensis – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
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Population
This species is widespread and abundant. Reported densities vary from 3/ha in continuous woodlands to
>21/ha in urban parks. Population and range are increasing (J Koprowski pers. comm.).
Current Population Trend: Increasing
Habitat and Ecology (see Appendix for additional information)
It is found in large blocks of hardwood or mixed forests, as well as in urban and suburban areas. Prefers
mature deciduous and mixed forests with abundant supplies of mast (e.g., acorns, hickory nuts). A
diversity of nut trees is needed to support high densities. Also uses city parks and floodplains. Seldom
far from permanent open water. In southern Alabama, narrow bands of hardwoods along ephemeral
streams were an important component of the habitat in even-aged pine and mixed pine-hardwood
stands. Rests in tree cavity or leaf nest; leaf nests apparently are made primarily by dispersing juveniles
18-19 weeks old. Nests in tree cavities or in leaf nests, usually 25 feet or more above the ground. Most
winter-spring litters are born in tree cavities, most spring-summer litters in leaf nests (Teaford 1986).
Cavities suitable for nesting are dry, 15-25 cm in diametre, 40-50 cm deep, with an entrance hole about
eight cm in diameter (Teaford 1986). Females may move young from tree cavity nest to leaf nest,
possibly to escape fleas.
In Illinois, most breeding occurs in December-February and May-June; slightly later in more northern
latitudes (see Koprowski 1994). One or two litters per year. First litter is produced mostly in FebruaryMarch, sometimes as early as January in some areas; second litter, July or August. Gestation lasts 44
days. Litter size most often is 2-3. Young are tended by female. Weaning is completed at about 10-12
weeks (in spring and/or late summer-early fall). Most breed as yearlings, sometimes sooner (as early as
five months) or later. Reproductive output, including the percentage of adults that produce young and
the number of litters per year, is positively correlated with mast abundance. Maximum reproductive
longevity is about a decade.
Home range averages 0.5-10 ha, with older males tending to have the largest ranges (Teaford 1986);
usually home range is less than five hectares (see Koprowski 1994). Not territorial, home range overlap
is extensive; social system is characterized by a linear dominance hierarchy. Disperses up to a few
kilometres from natal area upon approaching sexual maturity. Large-scale one-way emigrations have
been observed, generally coinciding with high population density and mast crop failure.
Taken by many predators, but predation does not appear to limit populations (Teaford 1986). Mean
annual mortality reported for adults is 42-57% (Koprowski 1994). Diet consists of seeds, fruits, nuts,
fungi, occasional insects and small vertebrates (e.g., bird eggs). Scatterhoarder; buries nuts and acorn in
fall for later consumption (winter-spring). Active during the day, particularly in the morning and late
afternoon, though unimodal activity may occur in winter. May be inactive for a day or two during
extremely cold, snowy weather.
Systems: Terrestrial
Threats
There are no major threats to this species.
© The IUCN Red List of Threatened Species: Sciurus carolinensis – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
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Conservation Actions (see Appendix for additional information)
The species occurs in a number of protected areas throughout its range.
Credits
Assessor(s):
Linzey, A.V., Koprowski, J. & NatureServe (Hammerson, G.)
Reviewer(s):
Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global
Mammal Assessment Team)
© The IUCN Red List of Threatened Species: Sciurus carolinensis – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
4
Bibliography
Koprowski, J. L. 1994. Sciurus carolinensis. Mammalian Species 480: 1-9.
Teaford, J. W. 1986. Eastern gray squirrel (Sciurus carolinensis). Section 4.7.1, US Army Corps of
Engineers Wildlife Resources Management Manual. Technical Report.
Wilson, D. E. and Ruff, S. 1999. The Smithsonian Book of North American Mammals. Smithsonian
Institution Press, Washington, DC, USA.
Citation
Linzey, A.V., Koprowski, J. & NatureServe (Hammerson, G.). 2008. Sciurus carolinensis. The IUCN Red List
of Threatened Species 2008: e.T42462A10699433.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
Disclaimer
To make use of this information, please check the Terms of Use.
External Resources
For Images and External Links to Additional Information, please see the Red List website.
© The IUCN Red List of Threatened Species: Sciurus carolinensis – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
5
Appendix
Habitats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Habitat
Season
Suitability
Major
Importance?
1. Forest -> 1.4. Forest - Temperate
-
Suitable
-
14. Artificial/Terrestrial -> 14.3. Artificial/Terrestrial - Plantations
-
Suitable
-
14. Artificial/Terrestrial -> 14.4. Artificial/Terrestrial - Rural Gardens
-
Suitable
-
Conservation Actions in Place
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Conservation Actions in Place
In-Place Land/Water Protection and Management
Conservation sites identified: Yes, over entire range
Additional Data Fields
Population
Population severely fragmented: No
© The IUCN Red List of Threatened Species: Sciurus carolinensis – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T42462A10699433.en
6
The IUCN Red List Partnership
The IUCN Red List of Threatened Species™ is produced and managed by the IUCN Global Species
Programme, the IUCN Species Survival Commission (SSC) and The IUCN Red List Partnership. The IUCN
Red List Partners are: BirdLife International; Botanic Gardens Conservation International; Conservation
International; Microsoft; NatureServe; Royal Botanic Gardens, Kew; Sapienza University of Rome; Texas
A&M University; Wildscreen; and Zoological Society of London.
THE IUCN RED LIST OF THREATENED SPECIES™