{{Short description|Species of rodent}} {{Speciesbox | name = Arizona gray squirrel | image = Arizona Gray Squirrel Sciurus arizonensis.jpg | status = DD | status_system = IUCN3.1 | status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=Linzey, A.V. |author2=Timm, R. |author3=Álvarez-Castañeda, S.T. |author4=Castro-Arellano, I. |author5=Lacher, T. |date=2019 |title=''Sciurus arizonensis'' |volume=2019 |article-number=e.T20005A22247935 |doi=10.2305/IUCN.UK.2019-3.RLTS.T20005A22247935.en |access-date=12 November 2021}}</ref> | status2 = G4 | status2_system = TNC | status2_ref = <ref name="NatureServe">{{cite web|title=Sciurus arizonensis|url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.100738/Sciurus_arizonensis|website=Natureserve Explorer|access-date=12 May 2024}}</ref> | genus = Sciurus | species = arizonensis | authority = Coues, 1867 | subdivision_ranks = Subspecies | subdivision_ref = <ref name="Thorington">{{cite book|last1=Thorington|first1=R.W. Jr.|last2=Hoffmann|first2=R.S.|year=2005|pages=754–818|editor1-last=Wilson|editor1-first=D.E.|editor2-last=Reeder|editor2-first=D.M|url=http://www.bucknell.edu/msw3|chapter=Sciurus (Sciurus) arizonensis|chapter-url=https://www.departments.bucknell.edu/biology/resources/msw3/browse.asp?id=12400097|title=Mammal Species of the World: a taxonomic and geographic reference|edition=3rd|publisher=The Johns Hopkins University Press|isbn=0-8018-8221-4|oclc=26158608}}</ref> | subdivision = * ''S. a. arizonensis'' * ''S. a. catalinae'' * ''S. a. huachuca'' | range_map = Sciurus arizonensis range map.svg | range_map_caption = Arizona gray squirrel range }}
The '''Arizona gray squirrel''' ('''''Sciurus arizonensis''''') is a tree squirrel, in the genus ''Sciurus'', endemic to the canyons and valleys surrounded by deciduous and mixed forests in eastern Arizona and northern Mexico.
It is threatened by habitat loss. The only other large squirrel that is within its range is Abert's squirrel, which has ear tufts and lives in pine forests. Although they act and look like other gray squirrels, the Arizona gray squirrel is actually more closely related to the fox squirrel.{{citation needed|date=April 2026}}
==Phylogeny and description== ''Sciurus arizonensis'' is a member of the order Rodentia and the family Sciuridae. It is primarily silvery-gray, with a white to cream belly and a gray tail frosted with white.<ref name="Thorington2012"/> It is distinguishable from ''Sciurus aberti'' by its longer flatter skull, broader rostrum, and having only one molar instead of two. ''S. arizonensis'' also has smaller ears with no tufts and a red/black stripe on the underside of their tail. Some sexual dimorphism can be seen in these squirrels, but it varies with some populations having larger males, and other populations having larger females.<ref name="Sciurus arizonensis">{{cite journal |last1=Best |first1=Troy L. |title=Sciurus arizonensis |via=The American Society of Mammalogists |date=June 23, 1995 |jstor=3504161 |journal=Mammalian Species |issue=496 |pages=1–5 |doi=10.1644/0.496.1 |s2cid=253925558 |doi-access=free }}</ref>
==Distribution and habitat== ''Sciurus arizonensis'' can be found in parts of Arizona, New Mexico and Sonora, Mexico.<ref name="Sciurus arizonensis"/> They live in the mountains<ref name="Cudworth-Koprowski">{{cite journal |last1=Cudworth |first1=Nichole L. |last2=Koprowski |first2=John. L. |title= Importance of Scale in Nest-Site Selection by Arizona Gray Squirrels |journal=The Journal of Wildlife Management |date=September 2011 |volume=75 |issue=7 |pages=1668–1674 |doi= 10.1002/jwmg.194|jstor=41418210|bibcode=2011JWMan..75.1668C |s2cid=53688725 }}</ref> ranging from low-elevation pine-oak forests to higher elevation coniferous forests.<ref name="Thorington2012"/> They are also found at mid-elevations in riparian habitats, usually broadleaf riparian forests.<ref name="ReferenceA">{{cite journal |last1=Frey |first1=Jennifer K. |last2=Hill |first2=Michael T. |last3=Christman |first3=Bruce L. |last4=Truett |first4=Joe C. |last5=MacDonald |first5=Stephen O. |title=Distribution and Habitat of the Arizona Gray Squirrel (Sciurus arizonensis) in New Mexico |journal=The Southwestern Naturalist |date=June 2008 |volume=53 |issue=2 |pages=248–255 |doi= 10.1894/0038-4909(2008)53[248:dahota]2.0.co;2 |jstor=20424923|s2cid=85657187 }}</ref> Riparian forests with large cottonwood and sycamore trees host the largest populations of this species.<ref name="Thorington2012"/>
The Arizona gray squirrel has had no recent expansion or reduction in the size of their range in New Mexico, although there has been some population decline. This is due to habitat loss and the introduction of Abert's squirrel, which has in some cases outcompeted the Arizona gray squirrel for resources.<ref name="ReferenceA"/>
==Ecology== Arizona gray squirrels nest in dreys woven from twigs and leaves in the canopies of large trees or, where available, in naturally-occurring tree cavities.<ref name="Thorington2012"/>
There is significant disparity in average territory sizes between sexes. Male home ranges are typically {{convert|113|ha|acre}}, while female ranges more commonly cover {{convert|14|ha|acre}}. Male typically attempt to maximize overlap with female territories, particularly during the mating season.<ref name="Thorington2012"/>
Arizona gray squirrels are hunted primarily by large raptors, foxes, and bobcats. When alarmed, they make a barking or chucking alarm call from an elevated location.<ref name="Thorington2012"/>
===Diet=== Arizona gray squirrels have a broad diet.<ref name="Cudworth-Koprowski"/> Tree seeds are an important food source, particularly the cones of pines, Douglas fir, and true firs, which are consumed by removing individual scales to expose seeds, and deciduous seeds such as acorns and walnuts.<ref name="Thorington2012"/> Additional food sources include tree sap, tree bark, insect galls, flowers, and fungi.<ref name="Thorington2012"/><ref name="Cudworth-Koprowski"/> Scatter-hoarding of seeds in leaf litter and topsoil is observed, but rare.<ref name="Thorington2012">{{cite book |last1=Thorington |first1=Richard W. |last2=Koprowski |first2=John L. |last3=Steele |first3=Michael A. |last4=Whatton |first4=James F. |date=2012 |title=Squirrels of the World |chapter=''Sciurus arizonensis'' (Coues, 1867) Arizona Gray Squirrel |url=https://archive.org/details/squirrelsofworld0000unse/mode/2up |publisher=Johns Hopkins University Press |page=43-44 |isbn=9781421404691 |access-date=11 April 2026}}</ref>
===Reproduction=== Female Arizona gray squirrels undergo a day-long estrus between February and May. Males have external testes between winter and summer, which withdraw into the body during the rest of the year.<ref name="Thorington2012"/> Multiple males engage in a mating chase with one female,<ref name="Thorington2012"/><ref name="Sciurus arizonensis"/> and a litter of three to four young is born in late spring to early summer.<ref name="Thorington2012"/>
Arizona gray squirrels have large variations in their diet, which has led to reproduction rates that vary year by year. Not all females breed each year, which can be seen by a lack of placental scarring. The timing of Arizona gray squirrel mating correlates with the prime time for flowers, which are a high energy food source for the energetically expensive costs of mating.<ref name="Sciurus arizonensis"/> Because mating is so energetically expensive, optimal reproduction timing is very important to ensure that offspring and parent will survive. This timing can differ between sexes and is largely dependent on the environmental change present in their habitat, which can often be fluctuating throughout the year and from year to year.<ref name="jmammal.oxfordjournals.org">{{cite journal|last1=Cudworth|first1=Nichole L.|last2=Koprowski|first2=John L.|title=Foraging and reproductive behavior of Arizona gray squirrels (Sciurus arizonensis): impacts of climatic variation|journal=Journal of Mammalogy|date=11 June 2013|pages=683–690|doi=10.1644/12-mamm-a-087.1|volume=94|issue=3 |doi-access=free}}</ref> Differences in the parental investment and a lack of food are responsible for shifts in male and female ranges. The opposite sexes have ranges that overlap with each other and during good mating conditions or season these ranges will expand and overlap more.<ref name="ReferenceB">{{cite journal|last1=Cudworth|first1=Nichole L.|last2=Korowski|first2=John. L.|title=Influences of mating strategy on space use of Arizona gray squirrels|journal=Journal of Mammalogy|date=October 2010|volume=91|issue=5|pages=1235–1241|doi=10.1644/09-mamm-a-426.1|jstor=40925730|s2cid=53680929 |doi-access=}}</ref>
==Conservation== An important conservation strategy for the survival of the Arizona gray squirrel is to protect their nesting habitat. This means maintaining large trees with closed canopies that allow access to resources and protection from predators.<ref name="Sciurus arizonensis"/>
==Interaction with humans== Arizona gray squirrels are frequently hunted for meat across most of their range. It is not considered to be a significant pest species due to inhabiting areas of low human population density.<ref name="Thorington2012"/>
==References== {{Reflist}}
{{S. Sciurinae1 nav}} {{Taxonbar|from=Q777282}}
Arizona gray squirrel Category:Rodents of Mexico Category:Rodents of the United States Category:Fauna of the Southwestern United States Arizona gray squirrel Category:Mammals described in 1867 Category:Taxonomy articles created by Polbot Category:Taxa named by Elliott Coues