Editing Northern flying squirrel

{{Short description|Species of rodent}}
{{speciesbox
| image = Northern Flying Squirrel, D'Alembert, 6400 Route d'Aiguebelle, Rouyn-Noranda, QC, Canada imported from iNaturalist photo 41110662.jpg
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn">{{cite iucn |author=Cassola, F. |date=2016 |title=''Glaucomys sabrinus'' |volume=2016 |page=e.T39553A22256914 |doi=10.2305/IUCN.UK.2016-3.RLTS.T39553A22256914.en |access-date=11 November 2021}}</ref>
| genus = Glaucomys
| species = sabrinus
| authority = ([[George Shaw (biologist)|Shaw]], 1801)
| subdivision_ranks = Subspecies
| subdivision = see text
| range_map = Glaucomys sabrinus map.svg
| range_map_caption = Northern flying squirrel<br />range<ref name="iucn"/><sup>(excludes ''[[Glaucomys oregonensis]]'')</sup>
}}

The '''northern flying squirrel''' ('''''Glaucomys sabrinus''''') is one of three species of the genus ''[[New World flying squirrel|Glaucomys]]'', the only [[flying squirrel]]s found in [[North America]].<ref name = "Walker and Paradiso 1975">Walker EP, Paradiso JL. 1975. ''Mammals of the World''. Baltimore: Johns Hopkins University Press.</ref><ref name = "Forsyth 1999">Forsyth A. 1999. ''Mammals of North America: Temperate and Arctic Regions''. Willowdale: Firefly Books.</ref>  They are found in coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and south to the mountains of North Carolina and west to [[Utah]] in the United States. They are light brown with pale underparts and grow to a length of {{convert|25|to|37|cm|in|0|abbr=on}}. They are proficient gliders but uncoordinated walkers on the ground. They feed on a variety of plant material as well as tree sap, fungi, insects, carrion, bird eggs and nestlings. They mostly breed once a year in a cavity lined with lichen or other soft material. Except when they have young, they change nests frequently, and in winter a number of individuals may huddle together in a shared nest. Unlike most members of their family, flying squirrels are strictly nocturnal.

==Subspecies==
Currently, 25 subspecies are recognized:<ref name=cat>{{Catalogue of Life 
     |id=ee65f583-647c-4dee-93dc-412c246e2b9e
     |title=Glaucomys sabrinus (Shaw, 1801)
     |option=
     |access-date= 25 October 2023
}}</ref>
{{div col}}
* ''G. s. sabrinus''
* ''G. s. alpinus''
* ''G. s. bangsi''
* ''G. s. californcus''
* ''G. s. canescens''
* ''G. s. coloratus''
* ''G. s. columbiensis''
* ''G. s. flaviventris''
* ''G. s. fuliginosus''
* ''G. s. fuscus''
* ''G. s. goodwini''
* ''G. s. gouldi''
* ''G. s. griseifrons''
* ''G. s. klamathensis''
* ''G. s. lascivus''
* ''G. s. latipes''
* ''G. s. lucifugus''
* ''G. s. macrotis''
* ''G. s. makkovikensis''
* ''G. s. murinauralis''
* ''G. s. reductus''
* ''G. s. stephensi''
* ''G. s. yukonensis''
* ''G. s. zaphaeus''
{{div col end}}

==Habitat and range==
The northern flying squirrel is found in [[coniferous]] and [[mixed coniferous forest]]s across the top of North America, from [[Alaska]] to [[Nova Scotia]], south to the mountains of [[North Carolina]] and [[Tennessee]] and west to Utah. The [[Humboldt's flying squirrel]] was formerly considered conspecific, but was found to be a [[cryptic species]], and now considered distinct. It is generally smaller and darker than northern flying squirrel and occurs in British Columbia, northern California, Washington and Oregon.

Two [[subspecies]] are found in the southern [[Appalachians]], the Carolina northern flying squirrel, ''G. s. coloratus'', and the West Virginia northern flying squirrel ''G. s. fuscus'', both of which are [[endangered]], although the West Virginia subspecies has recovered enough that it was delisted in August 2008.<ref>{{Cite web |url=http://ecos.fws.gov/tess_public/DelistingReport.do |title=USFWS Delisting Report dated 8/09 |access-date=2009-08-27 |archive-url=https://web.archive.org/web/20070728035106/http://ecos.fws.gov/tess_public/DelistingReport.do |archive-date=2007-07-28 |url-status=dead }}</ref><ref name=delisting/>

The U.S. Fish and Wildlife Service temporarily put the West Virginia northern flying squirrel back under protection on June 6, 2011, in response to a court order.  On appeal, the delisting was reinstated in March 2013.<ref name=delisting>{{cite web |title=Federal Register |url=https://www.govinfo.gov/link/fr/78/14022?link-type=pdf |website=govinfo.gov |access-date=6 December 2019 |date=4 March 2013}}</ref>

''G. s. californicus'', the San Bernardino flying squirrel, is found in the San Bernardino National Forest in California.<ref name=":0">{{cite web |title=San Bernardino Flying Squirrel (Glaucomys sabrinus californicus) {{!}} U.S. Fish & Wildlife Service |url=https://www.fws.gov/species/san-bernardino-flying-squirrel-glaucomys-sabrinus-californicus |access-date=18 October 2023 |website=FWS.gov |language=en}}</ref> In 2010, the [[Center for Biological Diversity]] petitioned the U.S. Fish and Wildlife Service to give the San Bernardino flying squirrel protections as an endangered species, but ultimately their request was denied.<ref name=":1">{{cite web |date=5 April 2016 |title=Federal agency declines to list San Bernardino flying squirrel as endangered |url=https://www.sbsun.com/2016/04/05/federal-agency-declines-to-list-san-bernardino-flying-squirrel-as-endangered/ |access-date=21 October 2023 |website=San Bernardino Sun}}</ref>  The U.S. Fish and Wildlife Service said, "in a thorough status review of the species using the best available science, the Service has found that the squirrel is abundant where it is found and that the threats to habitat loss from urban development, [[habitat fragmentation]], wildfire, urban air pollution and climate change do not pose significant threats to its long-term survival.".<ref name=":1" /> The Center for Biological Diversity argues that temperature changes are reducing the San Bernardino flying squirrel's forest habitat and negatively affecting the availability of the truffles it feeds on, with urban development impacting the area as well.<ref>{{cite web |title=San Bernardino flying squirrel |url=https://www.biologicaldiversity.org/species/mammals/San_Bernardino_flying_squirrel/index.html |website=www.biologicaldiversity.org}}</ref>

==Description==
These nocturnal, arboreal rodents have thick light brown or cinnamon fur on their upper body and greyish fur on the flanks and whitish fur underneath. They have large eyes and a flat tail. They can also be identified by their long whiskers, common to nocturnal mammals. The adult northern flying squirrel measures from 25 to 37&nbsp;cm long, and their weight can range from 110 to 230&nbsp;grams.

==Gliding==
[[File:Flying squirrel in a tree.jpg|left|thumb|Gliding]]

Flying squirrels do not actually fly, they glide using a [[patagium]] created by a fold of skin.<ref name = "Banfield 1974" /><ref name = "Forsyth 1999"/> From atop trees, flying squirrels can initiate glides from a running start<ref name = "Forsyth 1999" /> or from a stationary position by bringing their limbs under the body, retracting their heads, and then propelling themselves off the tree.<ref name = "Banfield 1974">Banfield AWF. 1974. The mammals of Canada. Toronto: University of Toronto Press.</ref><ref name = "Forsyth 1999" /> It is believed that they use [[triangulation]] to estimate the distance of the landing as they often lean out and pivot from side to side before jumping.<ref name = "Walker and Paradiso 1975"/> Once in the air, they form an "X" with their limbs, causing their membrane to stretch into a square-like shape<ref name = "Walker and Paradiso 1975" /> and glide down at angles of 30 to 40&nbsp;degrees.<ref name = "Forsyth 1999" /> They maneuver with great efficiency in the air, making 90&nbsp;degree turns around obstacles if needed.<ref name = "Forsyth 1999" /> Just before reaching a tree, they raise their flattened tails, which abruptly changes their trajectory upwards, and point all of their limbs forward to create a [[parachute]] effect with the membrane to reduce the shock of landing.<ref name = "Walker and Paradiso 1975" /> The limbs absorb the remainder of the impact, and the squirrels immediately run to the other side of the trunk or to the top of the tree to avoid any potential [[predator]]s.<ref name = "Walker and Paradiso 1975" /> Although graceful in flight, they are very clumsy walkers and if they happen to be on the ground in the presence of danger, they will prefer to hide rather than attempt to escape.<ref name = "Banfield 1974" /><ref name = "Forsyth 1999" />

==Diet==
A major food source for the squirrels are [[fungi]] of various species, although they also eat [[lichen]]s, all mast-crop nuts, tree sap, insects, carrion, bird eggs and nestlings, buds and flowers. The squirrels are able to locate truffles by [[olfaction]], though they also seem to use cues such as the presence of [[coarse woody debris]], indicating a decaying log, and [[spatial memory]] of locations where truffles were found in the past.<ref>[http://www.nature.ca/notebooks/english/flysquir.htm Northern Flying Squirrel], Natural History Notebooks</ref><ref>[http://www3.northern.edu/natsource/MAMMALS/Northe1.htm Northern Flying Squirrel] {{Webarchive|url=https://web.archive.org/web/20140910195400/http://www3.northern.edu/natsource/MAMMALS/Northe1.htm |date=2014-09-10 }}, Northern University</ref>

The northern flying squirrel is also known to cache food for when food supplies are lower. These caches can be in cavities in trees, as well as in the squirrels' nest. Lichens and seeds are commonly cached.{{citation needed|date=October 2023}}

==Behaviour==
[[File:Northern Flying Squirrel.JPG|thumb|Northern flying squirrel]]
[[File:Sue Cameron installs a new squirrel box (8554236001).jpg|thumb|Installation of a new [[Nest box|squirrel box]] off the [[Blue Ridge Parkway]]]]

Northern flying squirrels generally nest in holes in trees, preferring large-diameter trunks and dead trees, and will also build outside leaf nests called dreys and will also nest underground. Tree cavities created by [[woodpecker]]s as suitable nest sites tend to be more abundant in [[Old growth|old-growth forests]], and so do the squirrels, though harvested forests can be managed in ways that are likely to increase squirrel numbers. Nests may also be established in buildings, including parts of occupied homes. Except when rearing young, the squirrels shift from nest to nest frequently. They often share nests during winter months, forming aggregations. Usually, aggregate nests contain 4 to 10 individuals. The sharing of nests in winter by northern flying squirrels is important in maintaining body temperature (biothermal regulation), as northern flying squirrels do not hibernate, nor do they enter torpor states.

Northern flying squirrels gliding distances tend to be between 5 and 25&nbsp;metres, though glides of up to 45&nbsp;m and longer have been observed. Average glides are about 5&nbsp;m less for females than for males. [[Glide angle]] has been measured at 26.8 degrees and [[glide ratio]] at 1.98.

Since first documented by Shaw in 1801, the general understanding was that northern flying squirrels bred but once per year. Recently, in southern Ontario, Canada, polyestrous behaviour (two litters per year) has been documented for the first time.<ref>{{cite journal|last1=Patterson |last2=Patterson|first1=Jesse E.H. |first2=Stephen J.|title=Multiple Annual Litters in ''Glaucomys sabrinus'' (Northern Flying Squirrel)|year=2010|journal=Northeastern Naturalist|volume= 17 |issue=1 |pages=167–169|doi=10.1656/045.017.0115|s2cid=86589689}}</ref> This observation has since been confirmed by a second research team in New Brunswick, Canada.<ref>{{cite journal|last=Smith|first=Matthew|title=Evidence of Multiple Annual Litters in ''Glaucomys sabrinus'' (Northern Flying Squirrel)|year=2011|journal=Northeastern Naturalist |volume=18 |issue=3 |page=386|display-authors=etal|doi=10.1656/045.018.0312|s2cid=84791345}}</ref>

In southern Ontario, Canada, genetic evidence has recently shown hybridization with the rapid northward expansion and increased sympatry of [[southern flying squirrel]]s.<ref>{{Cite journal | doi=10.1111/j.1365-2486.2009.01948.x| title=Climate change induced hybridization in flying squirrels| journal=Global Change Biology| volume=16| issue=1| pages=113–121| year=2010| last1=Garroway| first1=Colin J.| last2=Bowman| first2=Jeff| last3=Cascaden| first3=Tara J.| last4=Holloway| first4=Gillian L.| last5=Mahan| first5=Carolyn G.| last6=Malcolm| first6=JAY R.| last7=Steele| first7=Michael A.| last8=Turner| first8=Gregory| last9=Wilson| first9=Paul J.| bibcode=2010GCBio..16..113G}}</ref>

==Predation==
Northern flying squirrels, along with [[pine squirrel]]s, are a primary prey species for the [[spotted owl]] (''Strix occidentalis'') and [[eastern screech owl]] (''Megascops asio'').<ref>{{Cite journal |last=Smith |first=Winston P. |date=2007-08-20 |title=Ecology of Glaucomys sabrinus : Habitat, Demography, and Community Relations |url=https://academic.oup.com/jmammal/article-lookup/doi/10.1644/06-MAMM-S-371R1.1 |journal=Journal of Mammalogy |language=en |volume=88 |issue=4 |pages=862–881 |doi=10.1644/06-MAMM-S-371R1.1 |issn=0022-2372|url-access=subscription }}</ref> Other predators include various other large birds, especially the [[great horned owl]] and [[Accipitridae|hawks]], as well as mammals including [[American marten]]s, [[Canadian lynx]]es, and [[red fox]]es.<ref>{{cite web |last=Studelska |first=Rebecca |title=Northern Flying Squirrel |url=https://www.sdgs.usd.edu/naturalsource/fauna/mammals/NorthernFlyingSquirrel.pdf |access-date=June 18, 2024 |publisher=South Dakota Department of Game, Fish and Parks, Division of Wildlife}}</ref>

==References==
{{Reflist}}
*Arbogast, B. S. (1999). Mitochondrial DNA phylogeography of the New World flying squirrels  ''[[Glaucomys]]'': implications for Pleistocene biogeography. ''[[Journal of Mammalogy]]'', '''80''', 142–155.
*Arbogast, B. S., Browne, R. A., Weigl, P. D. and [[Jim Kenagy|Kenagy, G. J.]] (2005). Conservation genetics of endangered flying squirrels from the Appalachian mountains of eastern North America.  ''Animal Conservation'',  '''8''', 123–133.
*Bakker, V. J., & Hastings, K. (2002). Den trees used by northern flying squirrels (''Glaucomys sabrinus'') in southeastern Alaska.  ''Canadian Journal of Zoology'', '''80''', 1623–1633.
*Carey, A. B., Kershner, J., Biswell, B., & De Toledo, L. D. (1999). Ecological scale and forest development: squirrels, dietary fungi, and vascular plants in managed and unmanaged forests.  ''Wildlife Monographs'' 5–71.
*Carey, A. B., Wilson, T. M., Maguire, C. C., & Biswell, B. L. (1997). Dens of northern flying squirrels in the Pacific northwest.  ''Journal of Wildlife Management'', '''61''', 684–699.
*Cotton, C. L., & Parker, K. L. (2000). Winter activity patterns of northern flying squirrels in sub-boreal forests.  ''Canadian Journal of Zoology'', '''78''', 1896–1901.
*Forsman, E. D., Otto, I. A., Aubuchon, D., Lewis, J. C., Sovereign, S. G., Maurice, K. J., & Kaminski, T. (1994). Reproductive chronology of the northern flying squirrel on the Olympic peninsula, Washington.  ''Northwest Science'', '''68''', 273–276.
*Martin, K. J., & Anthony, R. G. (1999). Movements of northern flying squirrels in different-aged forest stands of western Oregon.  ''Journal of Wildlife Management'', '''63''', 291–297.
*Mitchell, D. (2001). Spring and fall diet of the endangered West Virginia northern flying squirrel (''Glaucomys sabrinus fuscus'').  ''American Midland Naturalist'', '''146''', 439–443.
*Pyare, S., & Longland, W. S. (2001). Mechanisms of truffle detection by northern flying squirrels.  ''Canadian Journal of Zoology'', '''79''', 1007–1015.
*Pyare, S., Smith, W. P., Nicholls, J. V., & Cook, J. A. (2002). Diets of northern flying squirrels, Glaucomys sabrinus, in southeast Alaska.  ''Canadian Field-Naturalist'', '''116''', 98–103.
*Odom, R.H., W.M. Ford, J.W. Edwards, C.W. Stihler, and J.M. Menzel. 2001. Developing a habitat model for the endangered Virginia northern flying squirrel (Glaucomys sabrinus fuscus) in the Allegheny Mountains of West Virginia. [[Society for Conservation Biology|Biological Conservation]] 99: 245–252.
*Vernes, K. (2001). Gliding performance of the northern flying squirrel (''Glaucomys sabrinus'') in mature mixed forest of eastern Canada.  ''[[Journal of Mammalogy]]'', '''82''', 1026–1033.

==External links==
*[http://animaldiversity.ummz.umich.edu/site/accounts/classification/Glaucomys_sabrinus.html Animal Diversity Web - Glaucomys sabrinus]

{{S. Sciurinae2 nav}}
{{Taxonbar|from=Q1094722}}

[[Category:Glaucomys]]
[[Category:Rodents of the United States]]
[[Category:Rodents of Canada]]
[[Category:Natural history of the Great Smoky Mountains]]
[[Category:Mammals described in 1801]]
[[Category:Taxa named by George Shaw]]