Tamias minimus Bachman 1839
Creators: name: Wilson, Don E.
name: Thomas E. Lacher, Jr
name: Mittermeier, Russell A.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Sciuridae
Tamias
Tamias minimus

description: 171. Least Chipmunk <i>Tamias minimus</i> <b>French:</b> Tamia mineur / <b>German:</b> Kleines Backenhornchen / <b>Spanish:</b> Ardilla listada minima <b>Other common names:</b> Penasco Least Chipmunk (atristriatus), Selkirk Least Chipmunk (selkirki) <b>Taxonomy.</b> Tamias minimus Bachman, 1839, “Green River, near mouth of Big Sandy Creek,” Sweetwater County, Wyoming, USA. Twenty-one subspecies are recognized. <b>Subspecies and Distribution.</b> T.m.minimusBachman,1839—SonoranplateausofWyoming,NEUtahandNWColorado(USA). T.m.arizonensisA.H.Howell,1922—PrietoPlateau,extremeSofBlueRange,GreenleeCounty,Arizona(USA). T:m.atristriatusBailey,1913—SacramentoMts,SNewMexico(USA). T.m.borealisJ.A.Allen,1877—NMontana(USA),andlikelyNintoSaskatchewan(Canada). T.m.cacodemusCary,1906—WhiteRiverBadlands,PenningtonCounty,WSouthDakota(USA). T.m.canicepsOsgood,1900—YukonandNBritishColumbia(Canada). T:m.caryiMerriam,1908—SanLuisValley,Colorado(USA). T.m.chuskaensisSullivan&amp;Petersen,1988—ChuskaMts,ArizonaandNewMexico(USA). T:m.confinisA.H.Howell,1925—BighornMtsinNWyoming(USA). T.m.consobrinusJ.A.Allen,1890—Utah,Colorado,andtheborderareaofIdahoandWyoming(USA). T.m.grisescensA.H.Howell,1925—CWashington(USA). T.m.hudsoniusR.M.Anderson&amp;Rand,1944—NManitoba(Canada). T:m.jacksoniA.H.Howell,1925—OneidaCounty,NWisconsin(USA). T:m.neglectusJ.A.Allen,1890—SManitobaandSOntario(Canada),NMinnesotaandWisconsin(USA). T.m.operariusMerriam,1905—WColorado,NNewMexico,borderregionofUtahandWyoming(USA). T.m.oreocetesMerriam,1897—extremeSoftheborderareaofAlbertaandBritishColumbia(Canada),andMontana(USA). T.m.pallidusJ.A.Allen,1874—Montana,ENorthDakota,NEWyoming,extremeWSouthDakotaandNebraska,andadjacentWyoming(USA). T:m.pictusJ.A.Allen,1890—SIdahoandNUtah(USA). T. m. scrutator Hall &amp; Hatfield, 1934 — S &amp; C Washington, C Oregon, SW Idaho, W Nevada and California, on the E side of the Sierra Nevada (USA). T.m.selkirkiCowan,1946—knownonlyfromthetypelocalityatParadiseMine,nearTobyCreek,WofInvermere,BritishColumbia(Canada). T. m. silvaticus White, 1952 — border area between Wyoming and South Dakota (USA). The subspecific affinity of the populations in N Ontario and E Quebec is unknown but is likely to be the subspecies neglectus. <b>Descriptive notes.</b> Head—body 106-114-2 mm, tail 80-3-84-9 mm; weight 43-7-50-5 g. The Least Chipmunk is one of the smallest species of Tamias and is easily confused with other small sympatric Tamias species. Tail and ventral pelage vary from reddish yellow to brown. Nominate minimus has a general dull gray appearance, with buff and grizzled gray dorsal pelage and white ventral pelage. Ventral side oftail has rufous hairs, with black bands and buffy edge. Subspecies arizonensis has pale smoke-gray shoulders and bright tawny fur on ventral side oftail. It is similar to consobrinus, but with grayer and less tawny fur. Subspecies atristriatus has grayish fulvous sides, yellowish venter, and rusty gray to buffy white dorsal stripes. It is similar to operarius, but slightly larger and with darker and duller pelage. Subspecies borealis has a pale yellowish gray dorsal pelage, with black dorsal stripes and gray pale stripes. Sides are washed with yellowish brown, and ventral pelage is grayish white tinged with buff. Outer pair of pale stripes is white tinged with yellow. Subspecies cacodemusis very similar to pallidus, but paler and with a longer tail. Subspecies caniceps is very similar to borealis, but grayer, with more prominent postauricular patches and pure white ventral fur. The grayer fur is especially visible on head, feet, and tail. Subspecies cary: is similar to minimus, but paler, grayer, and with white facial stripes. Subspecies chuskaensis has the same dorsal coloration as minimus, but is slightly paler. Ventralside oftail varies from yellowish to reddish brown, and is outlined by pale buff. Upper surfaces offeet are gray. Subspecies confinis is similar to consobrinus but larger. It has some ocherous tawny coloration in the black dorsal stripes and during the winter, the white ventral fur becomes more buff in color. Subspecies consobrinus has a fulvous tail and ventral pelage. Subspecies grisescens is similar to pictus, but with narrower dark dorsal stripes, palertail, smallersize, and grayer and less buffy pelage. Subspecies hudsonius is similar to borealis, but generally darker and grayer. Hindlegs are dark gray and dark dorsalstripes are broader. Shoulders, back and rump have less reddish brown, and ventralside of tail is paler. Subspecies jackson: is similar to borealis, but with a darker face, head, and tail, and with a more intense tawny dorsal pelage and tail. Subspecies neglectus is similar to borealis, but larger with brighter coloration. Subspecies operarius is similar to the Yellow-pine Chipmunk (7. amoenus), but without the black post-auricular patch, and with a longer tail and fulvous coloration in dorsal side of tail. Subspecies oreocetes has gray dorsal pelage, tinged with yellow on sides. Outer pair of pale dorsal stripes is white, and top of head is grizzled gray. Dorsal side oftail is grizzled yellow and pale fulvous, bordered with black and fringed with ocherous on ventral side. Subspecies pallidus is similar to minimus, but larger and with some ocherous on sides. Subspecies pictus hasslate gray dorsum, with pale yellow on the buffy sides. The dark mid-dorsal stripe is black, and outer pair of dark stripes is seal brown with a rufous edge. Inner pair of pale stripes is slate gray, and outer pair is white. Upperside of tail is black and yellowish gray and ventral side is dark yellowish buff, fringed with yellowish gray and bordered with black. Subspecies scrutator is small and has cinnamon sides and is similar to consobrinus, but has lighter coloration with less rufescent. It also has a shortertail and darker head than pictus. Subspecies selkirki has grayish white post-auricular patches. Inner dorsal dark stripes are black and outer dark stripes are brown. Inner pale stripes are heavily colored with gray and brown. Sides are cinnamon-buff and ventralside oftail is between pinkish cinnamon and cinnamon-buff. Subspecies silvaticus is large and has a generally drab coloration. Sides are ocherous-buff and ventral side oftail is ocherous-orange fringed with black,itis darker and redder than pallidus. Chromosome numberof the Least Chipmunk is 2n = 38, subspecies of minimus have two different karyotypes. Subspecies arizonensis, caryi, minimus, neglectus, operarius, and pallidus have karyotype A which consists of four pairs of metacentric autosomes, six pairs of submetacentric autosomes, eight pairs of acrocentric autosomes, a submetacentric X chromosome, and an acrocentric Y chromosome. Subspecies cacodemus, confinus, scrutator, and silvaticus have karyotype B which consists of five pairs of metacentric autosomes, six pairs of submetacentric autosomes, seven pairs of acrocentric autosomes, a submetacentric X chromosome, and an acrocentric Y chromosome. Subspecies borealis and consobrinus have both karyotypes present. Hybrid karyotypes have been found in borealis and pallidus. Cytogenetic information is not available for the subspecies notlisted above. <b>Habitat.</b> Open and arid shrublands. The Least Chipmunk can move to other habitats when its preferred areas are occupied by other more aggressive species. For instance, on the eastern slopes of the Sierra Nevada, in California, the aggressive Yellow-pine Chipmunk can displace the Least Chipmunk to shaded pinyon pine areas. The Least Chipmunk also occurs in upland riparian habitat along the Green River. <b>Food and Feeding.</b> Diet of the Least Chipmunk consists mostly of seeds, but also includes fruits, flowers, fungi, leaves, and arthropods. Larders have been reported to contain 465-800 g of seeds cached for the winter. <b>Breeding.</b> Females enter estrus within seven days of emergence from hibernation, and mating season occurs between early April and mid-May. Gestation is ¢.28-30 days and newborns weigh ¢.2:3 g. Young are weaned at ¢.40-60 days. Lactating females are found May-August, depending on location. Young attain adult size in September. Average litter sizes vary across its distribution, with averages of 4-5-7 young, and a maximum of nine. The Least Chipmunk produces one litter per year, but females that lose a litter soon after the birth can have a second litter. In Michigan, some females potentially produce a second litter, butit is highly variable depending on location and year. Young reach sexual maturity at ¢.8 months, but probably do not reproduce before one year of age. <b>Activity patterns.</b> The Least Chipmunkis terrestrial, but sometimes climbs brush and trees to forage or even to build a leaf nest in branches or woodpecker cavities. It is diurnal and during winter, enters torpor from October-November to March-April. Most nests are built underground in a burrow system that can have up to four entrances, and can be 0-4-3-5 m in length; usually the nest is not deeper than 20 cm below the surface. <b>Movements, Home range and Social organization.</b> The average home range is estimated to be 1-2 ha for males and 0-66 ha females, in Alberta, Canada. The Least Chipmunk is considered to be trap shy, and is probably underrepresented in trap surveys. It also appears to be subordinate to more aggressive congeners and other ground squirrels, butis able to coexist in some environments, probably due to its efficiency in resource exploitation. It is very vocal, with 5-6 different types of alarm calls and several other types of vocalizations; however, a detailed analysis ofits vocalization system 1s needed. <b>Status and Conservation.</b> Classified as Least Concern on The IUCN Red List. Subspecies atristriatus is critically endangered, and selkirki is vulnerable. Overall, the current population trend of the Least Chipmunk is stable and there are no specific threats. It has a wide distribution and is typically evenly distributed and common within its area of occurrence; however, there are smaller, isolated populations in the southern portion of its distribution. The subspecies which inhabit this type of isolated area could be more susceptible to habitat loss due to anthropogenic factors. <b>Bibliography.</b> Anthony (1928), DeNatale et al. (2002), Ditto &amp; Frey (2007), Guralnick (2007), Hadley &amp; Wilson (2004a, 2004b), Kosoy et al. (2003), Linzey &amp; NatureServe (Hammerson) (2008x), Morris (2005), Root et al. (2001), Thorington etal. (2012), Vander Haegen et al. (2002), Verts &amp; Carraway (2001).
description: Published as part of <i>Don E. Wilson, Thomas E. Lacher, Jr &amp; Russell A. Mittermeier, 2016, Sciuridae, pp. 648-837 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions</i> on pages 784-785, DOI: 10.5281/zenodo.6840226