Examine individual changes

'{{more footnotes|date=July 2009}} {{Taxobox | status = LC | status_system = iucn3.1 | status_ref = <ref name=iucn>{{IUCN2008|assessors=Linzey, A. V. & NatureServe (Hammerson, G.)|year=2008|id=39553|title=Glaucomys sabrinus|downloaded=6 January 2009}}</ref> | trend = unknown | image = Glaucomys_sabrinus.jpg | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | subphylum = [[Vertebrate|Vertebrata]] | classis = [[Mammal]]ia | ordo = [[Rodent]]ia | familia = [[Sciuridae]] | genus = ''[[Glaucomys]]'' | species = '''''G. sabrinus''''' | binomial = ''Glaucomys sabrinus'' | binomial_authority = ([[Shaw (taxonomy)|Shaw]], 1801) | range_map = File:Northern flying squirrel Glaucomys sabrinus distribution map.png | range_map_caption = Northern flying squirrel range<ref>IUCN (International Union for Conservation of Nature) 2008. ''Glaucomys sabrinus''. In: IUCN 2014. The IUCN Red List of Threatened Species. Version 2014.3<br />http://www.iucnredlist.org. Downloaded on 12 January 2015</ref> }} The '''northern flying squirrel''' (''Glaucomys sabrinus'') is one of two species of the genus ''[[Glaucomys]]'', the only [[flying squirrel]]s found in [[North America]] (the other is the somewhat smaller [[southern flying squirrel]], ''G. volans''). Unlike most members of their family, flying squirrels are strictly nocturnal. ==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 west to [[California]]. Populations from the Pacific Coast of the United States are genetically distinct from those of ''G. sabrinus'' found elsewhere in North America, although they are considered to belong to the same species. Two [[subspecies]] are found in the southern [[Appalachians]], the Carolina northern flying squirrel, ''G. s. coloratus'', and the Virginia northern flying squirrel ''G. s. fuscus'', both of which are [[endangered]], although the Virginia subspecies has recovered enough that it was delisted in August 2008.<ref>[http://ecos.fws.gov/tess_public/DelistingReport.do USFWS Delisting Report dated 8/09]</ref> In California, the range extends to [[Yosemite Valley]].<ref name=LSN>Lichens in relation to management issues in the Sierra Nevada national parks, McCune, B., J. Grenon, and E. Martin, L. Mutch, Sierra Nevada Network, Cooperative agreement CA9088A0008. Oregon State University, Corvallis, Oregon, and Sequoia and Kings Canyon National Parks, Three Rivers, California, [http://openjournals.wsu.edu/index.php/pnwfungi/article/view/1031]</ref> The U.S. Fish and Wildlife Service put the flying squirrel back under protection on June 6, 2011. ==Description== The nocturnal, arboreal rodents have thick light brown or cinnamon fur on their upper body and greyish on the flanks and whitish 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">Forsyth A. (1999). ''Mammals of North America: Temperate and Arctic regions.'' Willowdale: Firefly Books.</ref> From atop of 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">Walker EP, Paradiso JL. (1975). ''Mammals of the World.'' Baltimore: Johns Hopkins University Press.</ref> 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 in order 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 in order 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 an 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, [[mushroom]]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], 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. The lichen ''[[Bryoria fremontii]]'' is likely an important winter food source in the United States [[Sierra Nevada (US)|Sierra Nevada]] range.<ref name=LSN/>{{rp|4}} ==Ecology== The northern flying squirrel also rekts spores of the fungi that they eat. ==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|suirrel 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. 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. In the United States [[Sierra Nevada (US)|Sierra Nevada]] range, they use the lichen ''[[Bryoria fremontii]]'' as a material for building nests, in addition to as a winter food source.<ref name="LSN"/>{{rp|4}} Northern flying squirrel gliding distances tend to be between 5 and 25 metres, though glides of up to 45 m and longer have been observed. Average glides are about 5 m less for females than for males. [[Glide angle]] has been measured at 26.8 degrees and [[glide ratio]] at 1.98., width is 4&nbsp;ft. 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, polyestrus behaviour (two litters per year) has been documented for the first time.<ref>{{cite news|last=Patterson & Patterson|first=Jesse E.H. & Stephen J.|title=Multiple Annual Litters in Glaucomys sabrinus (Northern Flying Squirrel)|year=2010|publisher=Northeastern Naturalist|location=Steuben, ME|volume= 17/1 |pages=167–169}}</ref> This observation has since been confirmed by a second research team in New Brunswick, Canada.<ref>{{cite news|last=Smith|first=Matthew|title=Evidence of Multiple Annual Litters in Glaucomys sabrinus (Northern Flying Squirrel)|year=2011|publisher=Northeastern Naturalist|location=Steuben, ME|volume= 18/3 |page=386|display-authors=etal}}</ref> In southern Ontario, Canada, genetic evidence has recently shown that hybridization with the rapid northward expansion and increased sympatry of southern flying squirrels.<ref>{{cite news|last=Garroway|first=Colin J.|title=Climate change induced hybridization in flying squirrels|year=2009|publisher=Global Change Biology|location=Mississauga, Canada|doi= 10.11.11/j.1365-2486.2009.01948.x|display-authors=etal}}</ref> ==Predation== Northern flying squirrels, along with [[pine squirrel]]s, are an important prey species for the [[spotted owl]] (''Strix occidentalis'') and [[eastern screech owl]] (''Megascops asio'').<ref>Direct observation of Screech Owl nesting box, Tom Knapp 3 Jan 2014</ref> Other predators include various other large birds, especially the [[great horned owl]], [[Accipitridae|hawks]], the [[American marten]], the [[Canadian lynx]], the [[red fox]], and the domestic [[cat]]. ==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 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}} [[Category:Flying squirrels]] [[Category:Mammals of the United States|Squirrel, Northern Flying]] [[Category:Mammals of Canada]] [[Category:Natural history of the Great Smoky Mountains]] [[Category:Animals described in 1801]]'