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M S AMMALIAN PECIES No. 769, pp. 1–10, 3 figs. Sciurus vulgaris. ByPeter W. W. Lurz, John Gurnell, and Louise Magris Published 15 July 2005 by the American Society of Mammalogists Sciurus vulgaris Linnaeus, 1758 Manchuria; chiliensis Sowerby, coreae Sowerby, and orientis Thomasaresynonyms. European Red Squirrel S.v.meridionalisLucifero,1907:45–46.Typelocality‘‘Laregione SciurusvulgarisLinnaeus,1758:63.Typelocality‘‘HabitatinEu- calabrese degli Appenini, e sovratutto quella parte che vien rope.’’ detta Sila’’ Sila, Calabria, Italy; alpinus Costa and silanus Hechtaresynonyms. CONTENT AND CONTEXT. Order Rodentia, suborder S. v. rupestrisThomas, 1907:410. Type locality‘‘Darine´,25miles Sciurognathi, family Sciuridae, subfamilySciurinae,genusSciu- N. W. of Korsakoff,’’ Saghalien Island; dulkeiti Ognev is a rus.Variationsincoatcolorandmorphologyledtothedescription synonym. of .40 subspecies (Corbet 1978; Ellerman and Morrison-Scott S.v.vulgarisLinnaeus,1758:63.Typelocality‘‘Europe.’’;restrict- 1965).Taxonomicstatusofsomeoftheseisuncertainandthenum- ed to ‘‘Sweden (Uppsala)’’ by Thomas 1911:148; albus Bill- ber of subspeciesdiffersbetweenauthors(Corbet1978;Loweand berg,albonatusBillberg,europeusGray,formosoviOgnev,ni- Gardiner1983;Sidorowicz1971;Wiltafsky1978).Regionaldiffer- gerBillberg,rufusKerr,typicusBarrett-Hamilton,andvarius encesinskullsizewithinthesubspeciesS.v.fuscoaterarelarger Gmelinaresynonyms. thandescribeddifferencesbetweenrecognizedsubspecies(Wiltaf- sky1976).Morphologicalcharacteristicsofthedifferentsubspecies mayrelatetoenvironmentalconditions(Sidorowicz1971).Thefol- DIAGNOSIS.Sciurusanomalusistheonlynaturallyoccur- lowingsubspeciesarebasedonSidorowicz(1971). ringcongenerinthePalearctic.IncontrasttoS.vulgaris(Fig.1), S. anomalushas4 rather than 6 padsonthehindfeet(Wiltafsky S.v.altaicusSerebrennikov,1928:422.Typelocality‘‘Kok-Suriv- 1978) and fur color on underpartsvariesfromastrongrustycolor er, estuaryoftheYamanuchriver,AltaiMountains.’’ tobuff yellow.S. lisoccursinJapan(Honshu,Shikoku,andKyu- S. v. anadyrensis Ognev, 1929:83. Type locality ‘‘50–60 km im shu), butnotontheislandofHokkaido,whereS.v.manchuricus NordenvonMarkowoundziehtsichflußaufwa¨rtsca.170km weit,’’ Anadyr territory, forest along Anadyr River, north of Markovo. S. v. argenteus Kerr, 1792:256. Type locality ‘‘the upper parts of the river Oby,’’ Siberia; corrected to left bank of the lower Yeniseiriver,WestSiberiabyMatschie(1904:313);albusDvi- gubsky, martensi Matschie, and nadymensis Serebrennikov aresynonyms. S. v. balcanicus Heinrich, 1936:41. Type locality ‘‘Lowerreaches ofKamchikRiver,easternBalkanMountains,Bulgaria;’’ame- liaeCabrera,croaticusWettstein,istrandjaeHeinrich,lilaeus Miller,andrhodopensisHeinricharesynonyms. S.v.bashkiricusOgnev,1935:47.Typelocality‘‘Buzulukpinefor- est,ShkotovskoeForest,SamaraProvince,BelayaRiver,Rus- sia.’’ S.v.exalbidusPallas,1778:374.Typelocality‘‘Regionofisolated pineforestsalongtheIrtyshandOb.Siberia,Russia;’’goltz- maieriSmirnovandkalbinensisSelevinaresynonyms. S. v. fuscoaterAltum,1876:75.Typelocality‘‘Harz,’’HarzMoun- tains,Germany;alpinusDesmarest,var.brunneaAltum,car- pathicus Pietruski, cinerea Hermann, fedjushini Ognev, var. fuscoatraAltum,var.gothardiFatio,kessleriMigulin,ognevi Migulin, rufus Barrett-Hamilton, rufus Trouessart, russus Miller,rutilansMiller,subalpinusBurg,andvilnensisUdziela aresynonyms. S. v. fusconigricans Dvigubsky, 1804:83–84. Type locality ‘‘Bar- guzin,Transbaikalia.’’ S. v. infuscatusCabrera, 1905:227–228. Type locality‘‘Losejem- plares que yo he estudiado proceden de las provincias de Madrid, Soria y Avil;.’’ bae¨ticus Cabrera, numantius Miller, andseguraeMilleraresynonyms. S. v. italicusBonaparte,1838:23. Typelocality‘‘Italy.’’ S.v.jacutensisOgnev,1929:81–82.Typelocality‘‘DieVerbreitung umfaßteinbreitesGebiet,welchessichvonKirensku¨berdas Gebirgsland zwischen Witim und Aldan zieht und den mit- tleren Teil des Jakutiengebiets einschließt,’’ wide area from Kirensk through themountainsbetween WitimandAldanas well as the central area of Jakutsk; arcticus Trouessart, bo- realis Brass, calotus Gray, and fuscorubens Dvigubsky are synonyms. S. v.jenissejensisOgnev,1935:47.Typelocality‘‘LowerTunguska, TurukhanskTerritory,Siberia.’’ S. v. leucourusKerr,1792:256. Typelocality‘‘England.’’ FIG. 1. Sciurus vulgaris from Valtellina, Italy. Photograph S. v. mantchuricus Thomas, 1909:501. Type locality ‘‘Khingan,’’ by GianfrancoScieghi. 2 MAMMALIANSPECIES 769—Sciurus vulgaris GENERALCHARACTERS.Sciurusvulgarisshowsnosex- ual dimorphism in size or fur color (Wiltafsky 1973). Sex can be determined by distance between genital opening and anus, which areverycloseinfemalesandca.10mmapartinadultmales.Skull and external measurements vary across the range depending on subspecies. Condylobasal length, 44.0–49.3 mm, may increase in Eurasiafromnorthtosouth(Wiltafsky1978).However,thispattern isconfused in centralEurope (Wiltafsky1973)andskullsizeand climatearenotrelated(Wiltafsky1973,1976).Rangesofbodyand skull measurements (in mm) are: length of body and head, 206– 250; length oftail, 150–205; length of hindfoot,51–63;lengthof ear, 25–36; basal length of skull, 40.2–48.4; zygomatic breadth, 29.0–35.2; length of nasals, 14.0–18.7; length of maxillary tooth- row, 8.5–10.4. Subspeciesdescriptionsareavailable(Miller1912; Ognev1940; Sidorowicz1971; Wiltafsky1976, 1978). Dorsal fur is uniformly dark but variable in color from deep brown to red brown or bright chestnut to gray brown or black. Wintercoatisthick,deepredtobrown,grayoralmostblackabove; thick red brown ear tufts are 2.5–3.5 cm long; tail hair is dense and dark red brown or black. Underside is pale, white, or cream. Summercoatisreddishbrownorchestnutabove;eartuftsaresmall or absent; and tail is thin, chestnut to creamy white. Color varies widely acrossthe continentalrangewithdorsalcolorrangingfrom dark red to black to brown to gray to blue (Corbet 1978; Ognev 1940). WinterfurofS. v. jenissejensisfromtheTurukhanskTerri- tory in Siberia is an intense bluish ash gray with slightdark gray mottling (Ognev 1940). Tail, feet, and ear tufts may be the same coloror contrastwiththeback. Many populations are polymorphic and several color types may be present. However, the relative proportion of color phases (black, brown, and red) varies geographically (Andera1985; Mar- kov 1961; Voipio 1970; Wiltafsky 1978; Zawidzka1958).InDen- mark,EuropeanredsquirrelsontheislandofBornholmaresmaller andtailandearsareblack,similartoScandinaviansquirrels.Pop- ulations on Sealand are dominated by light-colored reddish animals, whereas the rest of Denmark (eastern Jutland) haspolymor- phicpopulationssimilartoS.v.fuscoater(Degn1973).Populations where only 1 color type occurs are rare, such as on islands (Fu¨- nen—Wiltafsky1973).S.v.leucourusKerr,1792,endemictoBrit- ainandIreland,ischaracterizedbybleachingoftheearsandtail. However, introductions of S. v. vulgaris from Scandinavia into Perthshire, Scotland, in 1793 (Harvie-Brown 1880–81) and S. v. fuscoater from western Europe to Lothians, Scotland, in 1860 (probably) and Epping Forest, England, ca. 1910 (Harvie-Brown 1880–1881; Shorten 1954) complicate the picture in the United Kingdom.Somesquirrelsnowexhibitbleaching,whereasothersdo not. Black or melanistic squirrelsfoundincontinentalEuropeare rare in the United Kingdom, as are albino forms. In Europe, the proportion of dark color types decreases from southwest to north- east, except in mountainous areas, where dark color types may predominate. Coat color is not related to climate(Wiltafsky1973, 1977, 1978). FIG.2. Dorsal,ventral,andlateralviewsofcraniumandlat- DISTRIBUTION. Sciurus vulgaris occurs from the British eral view of mandible of Sciurus vulgaris (male from Lanzonby, Isles in the west across the Palearctic to the island of Hokkaido, near Penrith, Cumbria, United Kingdom; Tullie House Museum, Japan(LeeandFukuda1999),in theeast(Fig.3). Carlisle, Cumbria; specimen number 1967.24). Greatest length of craniumis49 mm.Photographsby P.W.W.Lurz. FOSSILRECORD.TheearliestrecordofS.vulgarisisfrom Ho´rvo¨lgyCavein Ho´r Valley,southernBu¨kkMountains,Hungary, ispresent.InItaly,Ireland,andBritain,S.vulgarisco-occurswith andismiddlePleistoceneinage(Jańossy1986).FossilsofS.vul- the introduced, larger S. carolinensis, which can exhibit some garis in Hungary are from Varboían stage (pre-Wu¨rm) sediments chestnut color over the back and down the limbs, but the coloris inLambrechtCave,easternBu¨kkMountains,theSubalyukian(low- not uniform as in the European red squirrel. Some European red erWu¨rm)sedimentsonthewesternsideofHo´rValley,andalayer squirrelscanappearquitegray,particularlyinwinter;however,S. atRejtek,eastofRe´pa´shuta,whichrepresentsatransitionalperiod vulgarishaseartuftsthatgrowinlatesummerandareprominent between thePleistoceneandtheHolocene(Jańossy1986).S.vul- in winter and spring. Morphologically, skull (Fig. 2) of the red garis occurs in France in latePleistocene(andWu¨rminterglacial squirrelissmallerthanthatofS. carolinensis,craniumisdeeper, period)depositsbearingforestfaunas(Fontećhevade,Santenay,Re- and postorbitalprocessesarelongerand narrower. gurdou,and Ronddu Barry—Chaline1972). France and Italy have 2 introduced species of Callosciurus, In Britain,S. vulgarisappearsinafewpoorlystratifiedcave C. erythraeus erythrogaster at Cap d’Antibes in southern France recordsassociated withforestfloras(Stuart1982).Theearliestre- andC. finlaysoniibocourtiiatAquitermeinPiedmont,Italy(Ber- cord is from landslip debris at Binnel Point, Isle of Wight, witha tolinoetal.1999;Mitchell-Jonesetal.1999).However,thedistinct radiocarbondateof4,4806100yearsago(Preece1986).S.vul- appearanceandcolorofboththese2speciesmakesanyconfusion garis occurs at the Ipswichian and Hoxnian interglacial stages withS.vulgarisunlikely.C.e.erythrogasterorthered-belliedtree basedonpollenspectraanalysis(Currant1989).InPoland,S.vul- squirrel has an olive-brown back and a reddish underside with garis has been linked to warmer phases in the late Quaternary grayish legs and feet. C. f. bocourtii appearsdark dorsallywitha appearing in the Vistulian and then, after a long gap, in the Vis- strikingwhiteundersideandflanks. tulian 3 stadial (Late Devensian)and during the Holocene(Nada- 769—Sciurus vulgaris MAMMALIANSPECIES 3 dividualsquirrelsandenergyexpenditure(mean6SE)peakedin springforredsquirrels(389.96122.5 kJ). ONTOGENYANDREPRODUCTION.Reproductioncan lastfromDecember–January,whenmalesandfemales9–10months oldorolderbecomesexuallyactive,toAugust–earlyOctober,when thelastlittersareweaned.Twobreedingpeaksoccurwithinayear, withmatinginwinterandspringleadingtospring-born(February– April) and summer-born (May–August) litters, respectively. First breeding may be delayed or missed when food is limited(Gurnell 1983, 1987), resulting in a shorter breeding season.Reproductive tractregressesinautumn.Whenactive,testesarelargeandscrotal; scrotum is sometimes darkly stained. Female tract has a Y-shape and embryo postattachment sites are sometimesvisible.Vulvabe- comes pink and swollen at estrus. Mating occurs with little prior courtshipotherthanamatingchase.Malesareattractedtoafemale FIG. 3. Distribution of Sciurus vulgaris L. across Eurasia. in heat by odor and follow her for 1 or more hours. The leading Theapproximaterangesofthe17subspeciesbasedonSidorowicz maleinthefollowinggrouptendstobeheaviestanddominantand (1971) are indicated by dashed lines: 1, S. v. altaicus; 2, S. v. accounts for most matings(Wautersetal. 1990). Matingsystemis anadyrensis;3,S.v.argenteus;4,S.v.balcanicus;5,S.v.bash- polygynous–promiscuous. kiricus; 6, S. v. exalbidus; 7, S. v. fuscoater; 8, S. v. fusconigri- Body mass and dominance rank in females are the best pre- cans; 9, S. v. infuscatus; 10, S. v. italicus; 11, S. v. jacutensis; dictors of fertility. Femalesmustattain a threshold bodymassbe- 12,S.v.jenissejensis;13,S.v.leucourus;14,S.v.mantchuricus; foreenteringestrus,300ginBelgium(WautersandDhondt1989), 15, S. v. meridionalis;16,S. v. rupestris;17,S. v. vulgaris. northernEngland(Lurz1995),andGermany(Mu¨nch1998);325g onJersey,ChannelIslands(MagrisandGurnell2002).Dailychang- es in body mass of an autoweighed female were 2.9% in the pre- chowski 1989). S. vulgaris occurs from Euerwanger Bu¨hl in Ger- gestation period, 3.0% in the pregnancy period, and 6.9% in the many, dated to 8,760 6 110 radiocarbon years ago (Ko¨nigswald lactation period (Lee 2000). Heavy females in high-quality home and Ra¨hle1975). rangeslivelongerandproducemoreoffspring(WautersandDhondt 1989).Lowereddensity-dependentbreedingsuccessresultsfroma FORM AND FUNCTION. The postcranial skeleton shows greaterproportionoffemaleslivinginpoorhabitatsathighdensity adaptationsforclimbingandleaping;bonesarerelativelylightand and more nonbreeding floaters at high density (Wauters and Lens hind limbs are disproportionately long and heavy (Shorten 1962). 1995).Femalescanreproducethe2ndsummeraftertheirbirthand Feetareplantigrade;longtoes(exceptthumbs,whicharereduced lowestageofafemalegivingbirthwas11months(Wiltafsky1978). to tubercles) have long curved claws. Well-developed tail is used Average lifetime reproductive success of a female red squirrel in forbalance,thermoregulation,andassignalingdeviceinbehavioral Belgium was5offspring(range,1–11offspring;n546—Wauters interactions.Epiphysealfusionoflongboneshasbeenusedtodis- and Dhondt1995). tinguishjuvenilesand adults(Degn1973; Lemnell1973). Malesarefecund for mostofthe breedingseason,withape- Skull is broad, smooth, and rounded with a deep, broadly riod of inactivity in autumn and possibly into winter. In alpine ovate braincase and a short, narrow, and deep rostrum (Barrett- habitats,malesareinactivefromlateAugusttoMarch(L.Wauters, Hamilton and Hilton 1910–1922; Miller 1912). Dental formula is pers.comm.).Malesdonotcareforyoung.Femalesarepolyestrus i 1/1, c 0/0, p 2/1, m 3/3, total 22. Upper front premolaris small andinheatforonly1dayduringeachestrouscycle.Adultfemales and peglike (Ognev 1940). Functional cheek teeth arerooted,low canproduce2littersof1–6(occasionallymore)offspringeachyear crowned,quadratewithroundedmarginalcuspsandconcavecen- when breeding starts early. In northern England, individuallitters tral area, and with upper teeth crossed by weak ridges (Tittensor rangefrom1to4(Lurz1995;Tonkin1983)andasupplementary- 1977).Lowerand2ndupperpremolarsaredeciduousandareshed fed population at Formby, United Kingdom, had means(6 SD) of at 16 weeks (Tittensor 1975). Wear of cheek teeth and growth of 3.1760.47and2.460.31offspringfor1994and1995(Shuttle- cementum (as well as mass of eye lens) can determine age (Degn worth1996). 1973; Karpukhin and Karpukhina 1971; Kiris 1937; Lemnell Young are blind, deaf, and naked at birth; mass is 10–15 g 1973).Themassorlengthofthebaculuminmalesisnotaccurate (Eibl-Eibesfeldt1951;Frank1952).Skinpigmentappearsonback fordeterminingage(Degn1973). andhairsemergeat8–9days.Hairscoverbodyby21days(Eibl- Body fur molts twice a year; spring molt proceeds from front Eibesfeldt 1951; Shorten 1954). Lower incisors are cut at 20–23 to back, autumn molt from back to front. Exact timing varies be- days,uppersat37–42days(Eibl-Eibesfeldt1951;Tittensor1975). tween individuals, particularly in relation to body condition. Ear Earsopenat28–35days;eyesopenat28–32days(Tittensor1975). tufts and tail hairs (from tip forward) molt once, with new hairs Youngbeginleavingnestandstarteatingsolidfoodat40–45days growing in late summer–autumn, and through to December in the (Eibl-Eibesfeldt 1951; Ognev 1940; Tittensor 1975) and are case of ear tufts. Juveniles molt to appropriate summer or winter weaned at 8–10 weeks, but suckling attempts by young and ma- adultcoatafterweaning(Ognev1940). ternal protective behavior may extend beyond this (Frank 1952; TheEuropeanredsquirrelhasfacial,carpal,andventralbody Gurnell 1991; Wiltafsky 1978). In Belgian, weaning is at 10–12 vibrissae (Beddard 1902; Bresslau 1912). Six setsofvibrissaeare weeks (Wauters et al. 1995). Molt to adult coat is at 3–4 months on the head: above the eyes, below the eyes, on the throat, under (Eibl-Ebesfeldt1951). thechin,abovethemouth,andonthenose(whiskers).Similarhairs Massatweaning, together withbeingbornearlierinthesea- arefoundonthefeet,theoutersidesoftheforelegs,theunderside son,affectslikelihoodoflocalsurvivalinthe1stfewmonthsoflife of the body, and at the base of the tail (Fraefel 1995). Hyva¨rinen (Wautersetal.1993).Nopostpartumestrusoccursuntilyoungare (1977) described the histology and ultrastructure of the nerve or- almostweaned. Juvenilesarerarely capableofbreedinguntil10– gansandSokolovandKulikov(1987)illustratedthevibrissalfield. 12monthsold,andmanyfemaleswean1stlitterwhen2yearsold Eyes are cone rich (Esteve and Jeffery 1998; Shorten 1954) (WautersandDhondt1995).Somefemalesareunsuccessfulinrear- with wide-angled vision and probably dichromatic color vision ing any young during a season. Intrauterine losses occur (Gurnell (Shorten 1954); the blind spotisa slenderhorizontalstripeabove 1991); further losses of young can occur during suckling and at thecenteroftheretina(Tittensor1977).Thesenseofsmellappears weaning (Wauters and Dhondt 1995). Young may be carried in highlydeveloped(Shorten1954; H. Wiltafsky,pers.comm.). mother’s mouth to a new nest during the suckling period (Lee Scentglandsareassociatedwithlargemucousglandsonside 2000). of mouth and sebaceous glands in the tissues of the upper and Sex ratios are ca. 1:1. In Finland, sex ratios remained rela- lowerlips(Schumacher1924).Atypeofapocrineglandoccurson tively constant over extensive areas and between years despite eithersideofthehead inthechinregion(Fraefel1995). changesinpopulationsize.Maletofemaleratiovariedlocallybe- Daily energy expenditures of red squirrels in Scotland are tween 43% and 58% males (Lampio 1965, 1967). Predation ex- available (Bryce et al. 2001). Large variations occur between in- acted a heavier toll on males during the breeding season(Lampio 4 MAMMALIANSPECIES 769—Sciurus vulgaris 1967).Basedoncapture–mark–recapturedata,operationalsexra- gut. The intestinal protozoan Eimeriaiscommon and causescoc- tioislocallymalebiasedinspruceplantationsinnorthernEngland cidiosis (Keymer 1983; Sainsbury and Gurnell 1995). Coccidiosis duringthebreedingperiod(Lurz1995). maybetheproximatecauseofdeathinundernourishedorstressed animalsanddeathsonalargescalehavebeenascribedtococcid- ECOLOGY. Across much of the Palearctic, S. vulgaris oc- iosis in Scandinavia (Lampio 1967), but not elsewhere. Eimeria cursinborealconiferousforestsconsistingmainlyoflarch(Larix), sciurorum is pathogenic in Britain. Other protozoa includeHepa- pine(Pinus),andspruce(Picea—GurnellandAnderson1996).In tozoonandToxoplasma.Ringwormfungalinfections(Microsporum central and southern Europe, S. vulgaris also occurs in broad- cookie and Trichophyton) are known, and bacterial infectionsare leaved and mixed woodlands. Mixtures of tree species provide a rare,althoughpasteurellosis(Pasteurellamulticoda)hasbeende- morereliableyear-to-yearseedfoodsupplythandosingle-species tected (Keymer 1983). Viruses isolated include parainfluenza(Vi- forestsbecauseofdifferencesinmastintervals,seedsize,andtim- zosoetal.1966),membersoftheencephalomyocarditisgroup(Vi- ing of seed dispersal (Lurz et al. 1995). Observed densities are zosoetal.1964;Vizoso1968),adenovirus(Sainsburyetal.2001), highestinmixeddeciduousandconifermixturesdominatedbypine and parapoxvirus (Sainsbury and Gurnell 1995; Sainsbury and and lowest in those dominated by Sitka spruce (Picea sitchensis) Ward 1996; Scott et al. 1981). Individuals infected with parapox- andinforestsjustreachingcone-bearingage(Gurnell1983,1991; virus have been found only in Britain and the disease resembles Lurz et al. 1995, 1998; Tonkin 1983a; Wauters and Lens 1995). contagious pustular dermatitis in sheep. The virus is highly path- European red squirrels readily use suburban parks and gardens ogenic and the resulting mortality is very high. S. carolinensisis (Magris and Gurnell 2002) as well as small woods and copses. unaffected by the virus, acts as a reservoir host (Sainsbury et al. Long-termdensitiesaveragebetween0.5and1.5individuals/hain 2000;Rushtonetal.2000),andthusmaycontributetothedecline bothconiferandbroad-leavedforests,butyear-to-yearfluctuations of the European red squirrel in Britain (Tompkins et al. 2001). can be large and vary with weather and the availability of tree Reports of myxomatosis, diptheria, distemper, and ‘‘consumption’’ seeds, particularly in monoculture plantation forest (Wauters and are unfounded. Malignant melanoma on upper and lower eyelids Lens 1995). Very low densities of 0.02–0.2 squirrels/ha occur in withmetastasistothelungwasobservedinEuropeanredsquirrels boreal forests in Scandinavia and large conifer forestsinnorthern (Fukuietal.2002).Nutritionaldiseasesduetoalackofselenium EnglandandScotland(AndreńandLemnell1992;Halliwell1997a; and an imbalance of calcium and phosphorus have been reported Lurzetal. 1995). Populationscanrecoverfromverylowdensities in both wild and captive European red squirrels(J. Gurnell,pers. in2–3years.Annualcyclesofnumbersoccur,withlowsinspring comm.;Gurnelletal.1990; KeymerandHime1977). beforebreedingand peaksinautumnafterbreeding. Primary foods are berries, fruits, fungi, and tree seeds but Habitatfragmentationasaresultofroadbuildingandurban- other foodsareeaten when seedsarenotavailable.Theseinclude ization with loss of habitat can decrease population size, because the buds and bark of trees, flowers, shoots, and other green plant of reduced immigration rates with a concomitant decrease in ge- materialaswellas bird eggs, nestlings,invertebrates,andlichens netic diversity relative to nonisolated populations (Wauters 1997; (Moller 1983; Nour et al. 1993; Ognev 1940; Rajala and Lampio Wauters et al. 1994a). Small, isolated populations have higher 1963;WautersandDhondt1987).Treeseedsarescatterhoardedin chancesofextinction,althoughviablepopulationspersistinsmall, the autumn and fungi are cached on branches in trees (Gaukler highly fragmented woodlands on the island of Jersey, Channel Is- 1963;LurzandSouth1998;SulkavaandNyholm1987).Hoarding lands(MagrisandGurnell2002).Woodlandsize,distancebetween appearsmore intenseinbroad-leavedthaninconiferforests(Ton- woodlands, and habitat composition affect European red squirrel kin1983a;WautersandCasale1996).Europeanredsquirrelsthat presence (Andreń and Delin 1994; Celada et al. 1994; Rodriguez spendmoretimerecoveringhoardsaremorelikelytosurvive,and and Andreń 1999; Rushton et al. 1999; Verboom and van Apel- inthecaseoffemales,tendingtoweanmoreyoungintheirlifetime doorn1990; Wautersetal.1994a). (Wauters et al. 1995). Their spatial memory for the location of Inthewild,meanexpectationoflifeat6monthsofageisca. storedfooddoesnotappeartolastaslongasthatofS.carolinensis 3years;someindividualsmayliveto7yearsofageandincaptivity (MacDonald1997). for up to 10 years (Tittensor 1975). Causes of death include pre- Between60%and80%ofactiveperiodmaybespentforaging dation,starvation,verycoldweather,andpossiblyparasiticdisease andfeeding,withmoretimespentinconiferousthanindeciduous in undernourished animals. Year-to-year survival is positively re- woodland(Moller1983,1986;Tonkin1983b;Wautersetal.1992). lated to availability of autumn–winter tree seeds (Gurnell 1983). Winter activity patterns are influenced by the need to forage for Onaverage,75–85%ofjuvenilesdisappearduringtheir1stwinter; food and to conserve energy in the nest (Reynolds 1985a). Euro- average year-to-year survival improves thereafter to ca. 50%. An- pean red squirrels are active all year (they do not hibernate) but nual predation rate is 16% for adults, with a population turnover may remain in nest for several days during severe winter weather ofupto54%inspruceplantationsinnorthernEngland(Lurz1995; (Tonkin 1983b; Wauters and Dhondt 1987). The European red Petty et al. 2003). In the seminatural forestsof BavarianNational squirrelisdiurnal;onsetofdailyactivityisrelatedtosunrise,but Park, predation rates were 61% (Mu¨nch 1998). Predators include termination is not related to sunset. Considerable individualvari- pinemarten(Martesmartes),wildcat(Felissilvestris),someowls, ationexistsbutgenerally,asinglemainactivephaseoccursduring andraptorssuchasgoshawk(Accipitergentilis)andbuzzard(Buteo winter,peakinginlatemorning.Duringsummer,2phasespeak2– buteo—Halliwell1997b;Kenwardetal.1981;MarquissandNew- 4hoursaftersunriseand2–4hoursbeforesunset.Springandau- ton 1982; Pulliainen 1984; Pulliainen and Ollimaki 1996). Stoats tumnactivitypatternsareintermediatebetweenwinterandsummer. (Mustela erminea) may take nestlings, and foxes (Vulpes vulpes), High winds, very hot or cold conditions, and heavy rain reduce cats(Feliscatus),anddogs(Canisfamiliaris)couldtakeEuropean activity.S. vulgarismaylieoutstretchedonabranchtokeepcool red squirrels when they are on the ground. Domestic cats are im- during very hot weather. Standing water may be sought in hot portantpredatorsinsuburbanareas(MagrisandGurnell2002).S. weather.Foodavailabilityalsoinfluencesactivity;activitypatterns carolinensis is not a direct cause of mortality. Humans influence and nest use are described by Tonkin (1983b) and Wauters and mortalitybydestroyingoralteringhabitats,causingroadcasualties, Dhondt(1987). or controllingpopulationsunder license. Nestsordreysarespherical,ca.30cmindiameterbutsome- Oneflea,Monopsyllusscriurorum,isspecifictoEuropeanred times larger, and situated close to the trunk of a tree or in a fork squirrels. Another flea,Orchopeas howardii,camewithS.caroli- in thebranches, usually from 6 m upward, but they canbelower. nensis from North America and is sometimes found on European InnorthernGermany,15%of110surveyeddreysinpredominantly redsquirrelsinBritain(BlackmoreandOwen1968;Shorten1954). deciduouswoodlandwere,8m,64%were8–16m,and22%were Taropsylla octodecimdentata present in continental Europe is .16mhigh(Borkenhagen2000).Nestsareoftenhiddenbyclimb- found locally in Scotland and England (Coles and Jessop 1993). ing plants (Magris 1998; Tonkin 1983a). Outer layers consist of Themostcommontickisthesheeptick(Ixodesricinus).Thespi- twigs,sometimeswithneedlesorleavesattached;innercavity(12– rochaetes Borrelia afzelii, B. burgdorferi sensu lato, and B. b. 16cmindiameter)islinedwithsoftmaterialsuchasmoss,leaves, sensustrictoweretransmittedtoS.vulgarisbyfeedingticks(Hu- needles,clippeddrygrass,andbark.Innerliningconsistsof57% mair and Gern 1998).SuckingliceincludeEnderleinellusnitzchi grass, 19% moss, 16% needles, and 8% of other materials (n 5 and Neohaematipinus sciuri. Mange mites have been found, but 50—Tittensor1970).Individualsuse2,3,ormoredreysatatime, signsmaybemistakenforsick,undernourishedsquirrelssuffering frequently alternating dreys on consecutive nights. Up to 8 dreys from alopecia and heavy infestations of fleas and lice. Helminths wereusedwithin2weeks(Halliwell1997a;Lurz1995).Nestsare are uncommon but Enterobius nematodes have been found in the of 2 types: day nests used for resting and night nests used for 769—Sciurus vulgaris MAMMALIANSPECIES 5 sleeping, although the latter also may be used for diurnal resting ofJersey,ChannelIslands(n511,22);6.2261.62,20.4465.2 (WautersandDhondt1990).Dreycountsareacrude,relativeindex and 19.7 6 6.06, 31.4 6 8.76 in conifer-dominated habitats in ofpopulationsizeorhabitatuse(Cagninetal.2000;Gurnelletal. northern England (n 5 56, 4) and Scotland (n 5 5, 7—Halliwell 2001; WautersandDhondt1988;Yalden1980).Hollowtreesmay 1997a; Lurz 1995; Magris 1998; Wauters et al. 2000); and very beusedasdens,especiallyinbroad-leavedwoods.Denserspruce largeranges(upto47ha)inmixedhigh-altitudeforestinBavarian trees rather than pines are preferred for drey location in conifer NationalPark(Mu¨nch1998).Homerangesoverlap,particularlyin plantations(Halliwell1997a; Lurzand Garson1998). areasofabundantfood,butextentofoverlapcanbesmall,notably Occasionally, European red squirrels have caused economic inbreedingfemales,whichreducetheirrangewhensucklingyoung bark-strippingdamagetoconiferplantationforestbetweenMayand (Lurzetal.2000; WautersandDhondt1985, 1992). July in Britain, especially when densities of S. vulgarisapproach European red squirrels run across the ground in a series of 2 individuals/ha (Kenward 1983; Shorten 1962). Ringbarking, leaps with the tail held out behind. They frequently stop and sit which results in dieback and wind-snap, and crown damage also uprightontheirhindlegsinanalertposture;theheadisheldhigh occur.Locally,thesesquirrelsmaybeanuisancetoseedorchards with ears erect and nose sniffing the air. They are agile climbers and horticulturalcrops. andcanmoverapidly,leapingfrombranchtobranchandbetween Theeffectsofsupplementaryfoodonredsquirrelpopulations trees up to 4 m apart. Theyclimb down tree trunksheadfirstwith areequivocal.Aheavilysupplementary-fedconifersitehadhigher frequent pauses. When disturbed, they move up on the opposite densities compared to a conifer control site (Shuttleworth 1996). sideofatreetotheobserverorpredator,or‘‘freeze’’motionlesson However, supplemental feeding did not allow all females to enter a branchoragainstthetreetrunk.Theyareabletoswim. breedingconditionortoproduceyoungandsomedegreeofrepro- Foodisheldandrotatedbyforefeet.Conebractsaregnawed ductive suppression occurred at the fed site as a result of high offtoexposeseedand thewingsarediscarded. populationdensities.Also,heavyparasiteburdensandevidenceof Dispersalisnotsex-biasedandstrictphilopatryisrare;local preweaning mortality were found in the supplementary-fed site competition determines dispersal distance (Wauters et al. 1994c). (Shuttleworth 1996). Adding supplementary feed to a previously Dispersal in spring probably involves animals moving away from ‘‘unfed’’coniferecosystemincreasedbreedingactivityandturnover marginal, overwinteringhabitats;summerdispersalinvolvesearly- ratesbutdidnotsignificantlyraisedensitiesinfedareastoabove bornyoung;anddispersalinautumncaninvolveadultsaswellas thoseinthecontrolsite(Lurz1995).Broad-leavedwoodswithsup- juveniles.Aseasonalsexbiasindispersaloccurs,withmoremales plemental forage held higher densities of European red squirrels dispersinginspringandmorefemalesinautumn(Lurzetal.1997; but turnover and immigration were higher than in woods without WautersandDhondt1993).Postbreedingdispersalofadultfemales added forage(MagrisandGurnell2002). occurred after seasonal changes in seed availability (Lurz et al. European red squirrels can be captured with wire cage traps 1997). Dispersal of females is affected by food availability; dis- (single catch) commonly fitted with a box at the back for the ani- persal of males is affected by distribution of females (Lurz et al. malstoshelterin.Woodenboxtrapsalsocanbeused(Magrisand 1997).MassmovementshavebeenreportedfromtheformerUnited Gurnell2002;Mu¨nch1998).Amixtureofsunflowerseeds,peanuts, SovietSocialistRepublicin autumnswithpoorfoodsupplies(Og- and hazelnuts and pieces of apple are successfulbait.Trapsmust nev 1940). be checked midmorning and last thing before night. Wild adult Urine is an important form of olfactory signal; vaginalsecre- Europeanredsquirrelscansufferheavymortalityshortlyaftercap- tionsinestrousfemalesmaycomplementurineasasignofrepro- ture when confined to cages; this is probably related to stress or ductive condition, drawing males from .1 km away (Lurz 1995). ‘‘shockdisease,’’whichisassociatedwithareductioninbodytem- Scent marking occurs at specific places within home range (on peratureandhypoglycemia(Mersonetal.1978).Eartags,eartat- branchesortreetrunks)byusingurineandsecretionsfromglands toos,coloredcollars,tailtopiary,furdying(Rice-Oxley1993),and on the chin by face-wiping behavior (Fraefel 1995; Holm 1991). radiocollars are successful marking methods. Census methods in- Scent marks denote occupation of home range, social status, and cludeconelines,dreycounting,visualcounts,nestboxes(Shuttle- reproductive condition. Countermarking was observed at point worth 1996), hair tubes, focal feeding points, and snow tracking. sourcesoffoodsuchasfeedingstations(Magris1998).Vocalcom- Mostofthesemethodswillnotgiveveryaccurateestimatesofpop- munication is associated with typical body postures and includes ulation density butwillindicatepopulationtrendsovertime(Gur- loud and soft chucking calls, an explosive ‘‘wrruhh’’ sound, and nelletal.2001, 2004). variousmoansandteethchattering.Youngmakeshrillpipingcalls. In captivity, nestlings can be raised on a low-lactose milk Aggressive acts include loud chucks, foot stamping, and tail flag- substitute followed by soft fruits and shelled nuts as they are ging.Aggressiveencountersmayresultinhigh-speedchasing,tail weaned (Dickinson 1995). Milk should be offered at body heat biting,andscreaming(Eibl-Eibesfeldt1951).Theycanoccurwhen every 2 h during the day and every 3 h during the night. Young males group together in mating chases as they follow a female in animals need a constant heat source of ca. 258C (a heating pad heat.Thedominantmaleisatthefrontofthegroupandistheone covered with a towel is considered suitable). Defecation and uri- mostlikelytomatewiththefemale(Wautersetal.1990). nation should be encouragedaftereachfeedbygentlestimulation of the anogenital area with warm, damp cotton wool. The young GENETICS. Diploid chromosomes number is 40; FN 5 70 shouldbecarefullydabbedcleanofmilkaftereachfeed.Caremust and 72 (Zima and Kral 1984). Phylogenetic relationships and ge- be taken to offer a balanced diet to avoid metabolic bone disease neticdistancebetweenS.vulgarisandsquirrelsfromNorthAmer- (Gurnelletal.1990;SainsburyandGurnell1995).Coccidiosiscan ica have been described by Oshida and Masuda(2000).Compari- occurincaptiveanimals,particularlyifanimalsarestressed.Toxo- sonsofkaryotypesand ribosomalRNAgenesbetweenS.vulgaris plasmosis, which can be fatal to European red squirrels, can be andS.lissuggestthattheymaybeconspecificratherthandistinct contractedfromdomesticcats. species(Oshidaetal.1996;OshidaandYoshida1997).InBelgium, although small populationshave highlevelsofbandsharing,pop- BEHAVIOR.Europeanredsquirrelsaresolitaryformuchof ulationprocessesratherthangeneticfactorsaretherealthreatsto thetimebutcommunalnestingmayoccur,particularlyinthewinter smallisolatedpopulations(Wautersetal.1994b).Highband-shar- and spring;animalsthatsharedreystendtobefamiliarwitheach ing rates and low levels of immigration also were reported from other(Holm1991;WautersandDhondt1990).Socialorganization fragmentedforestsinGermany(WiegandandSchro¨pfer1997).Mi- is based on dominance hierarchies among and between sexes, al- tochondrialDNAfromEuropeanredsquirrelsfrom12locationsin thoughmalesarenotnecessarilydominanttofemales(Wautersand the United Kingdom and 3 from mainland Europe indicated no Dhondt 1989). Dominantanimalstendtobelargerandolderthan obvious geographicalpattern acrosstheUnitedKingdom,thusthe subordinateanimalsanddominantmalestendtohavelargerhome useoflarger geographicallydistinctpopulationswithintheUnited ranges than subordinate males or females, but much variation in Kingdomforaugmentationofsmallisolatedpopulationsisunlikely range size is related tohabitatquality, season,andsexualactivity toposegeneticproblems(Barrattetal.1997,1999).However,the as well as changes in food availability (Andreń and Delin 1994; UnitedKingdomhasbeensubjecttointroductionsfromcontinental LurzandGarson1998;Lurzetal.1997,2000;WautersandDhondt Europe(Harvie-Brown1880–1881)andthegeneticstructureofthe 1985, 1992). Average home-range area for both sexes varies with European red squirrel populations in the 3 most northern regions location and habitat, but males tend to have larger home ranges ofEngland(Cumbria,Northumberland,andDurham)wasverydif- than females. Observed average sizes (ha, 6 SD, females then ferentwithhighlysignificantgeneticsubdivisionbetweenCumbria males,respectively)include2.461.61,6.264.94ontheisland and northeastern England (Haleetal.2001a,2001b).Defragmen- 6 MAMMALIANSPECIES 769—Sciurus vulgaris tation of the landscape as a result of large-scale forestation has asianredsquirrel,Sciurusvulgaris,inrelationtoforestfrag- resulted in significant genetic and morphological changes in local mentation.Oikos70:43–48. squirrel populations over the last 40 years (Hale and Lurz 2003; ANDREŃ, H., AND P. A. LEMNELL. 1992. Population fluctuations Haleetal.2001b, 2004; Lurz2002). andhabitatselectionintheEurasianredsquirrelSciurusvul- garis.Ecography15:303–307. CONSERVATION STATUS. The European red squirrel is BARRATT, E. M., J. GURNELL, G. MALARKY,R.DEAVILLE,ANDM. widespreadandcommonovermuchofitsrange.Itisagameanimal W. BRUFORD. 1999. Genetic structure of fragmented popu- in northern conifer forests of the Palearctic and is hunted for its lationsofredsquirrel(Sciurusvulgaris)intheUK.Molecular fur (Gurnell 1987). Local range expansions have occurred as a Ecology8:S55–S63. resultoftranslocations(ontoDutchorGermanislandsintheNorth BARRATT, E. M.,G.MALARKY,S.BODDY,J.GURNELL,ANDM.W. Sea—Degn 1973, 1974; Wiltafsky1978).However,inBritainand BRUFORD. 1997. Genetic diversity among fragmented pop- Ireland, interspecific competition from alien S. carolinensis has ulationsofredsquirrelSciurusvulgaris:apreliminarystudy. caused the loss of European red squirrels over large areas (Bryce Pp. 61–66 in The conservation of red squirrels,Sciurus vul- 1997; Gurnell 1987, 1996a, 1996b; Gurnell and Pepper 1993; garis L. (J. Gurnell and P. W. W. Lurz, eds.). People’s Trust Lloyd 1983; Lurz et al. 2001; Reynolds 1985b; Skelcher 1997; forEndangeredSpecies,London,UnitedKingdom. Staines1986;Teanganaetal.2000;Usheretal.1992;Wauterset BARRETT-HAMILTON,G.E.H.,ANDM.A.C.HINTON. 1910–1922. al. 1997). Population declines also have been observed in Pied- A history of British mammals. Gurney and Jackson, London, mont, Italy, where the gray squirrel was introduced in 1948 (Cur- UnitedKingdom. rado 1998; Currado et al. 1987; Lurz et al. 2001; Wauters et al. BEDDARD, F. E. 1902. Observationsuponthecarpalvibrissaein 1997).S.carolinensishasacompetitiveadvantageinbroad-leaved mammals. Proceedings of the Zoological Society of London woodlands,itsnativehabitat,whereitreacheshigherdensitiesthan 1902:127–136. European red squirrels (Kenward et al. 1998). S. carolinensis is BERTOLINO,S.,I.CURRADO,ANDP.J.MAZZOGLIO. 1999. Finlay- more efficient at digesting acorns than are European red squirrels son’s(variable)squirrelCallosciurusfinlaysoniinItaly.Mam- (Kenward and Holm 1993). However, competitionforfoodandin- malia63:522–525. terferencecompetitionamongadultS.vulgarisandS.carolinensis BLACKMORE, D. K., AND D. G. OWEN. 1968. Ectoparasites: the is not solely responsible for the replacement of S. vulgaris by S. significanceinBritishwildrodents.SymposiaoftheZoological carolinensis(WautersandGurnell1999;Wautersetal.2001).Dif- SocietyofLondon24:197–220. ferencesbetween the 2 speciesin fataccumulationintheautumn BONAPARTE, C. L. 1838. Principe di Canino e Musigano, 1838. may contribute to the replacement process in deciduous habitats Iconografia dellaFauna Italicaper lequattro classideglian- (KenwardandTonkin1986),butarenotsignificantinconiferhab- imali vertebrati. Volume 1 (Mammiferi e Ucelli). Salviucci, itats where autumn and winter food suppliesaremore predictable Rome,Italy1832–1841. and maneuverability to feed on cones in the canopy is important BORKENHAGEN, K. 2000. Untersuchungen an Eichho¨rnchennes- (Lurz and Lloyd 2000). The presence ofS. carolinensisdecreases tern.Faunistisch-O¨kologischeMitteilungen8:1–7. summerbreedinginEuropeanredsquirrelsanddecreasesjuvenile BRESSLAU, E. 1912. Die ventralen Tasthaare der Eichho¨rnchen, recruitmentin theautumn(WautersandGurnell1999;Wauterset ihre Funktion und ihre Verbreitung. Zoologisches Jahrbuch al. 2000, 2001).S. carolinensisalsostealstheseedcachesofred 15:479–492. squirrels in areas of overlap, which results in a reduced energy BRYCE, J. 1997. Changes in the distributions of red and grey intakeinEuropeanredsquirrelsandareducedbodymassinspring squirrelsinScotland.MammalReview27:171–176. (Wauters et al. 2002). Parapoxvirus disease mediates interspecific BRYCE, J. M., J. R. SPEAKMAN, P. J. JOHNSON, AND D. W. MAC- competitioninBritain(Rushtonetal.2000;Tompkinsetal.2001) DONALD. 2001. Competition between Eurasian red and in- but no evidence exists that this occurs in continental Europe (L. troduced eastern grey squirrels: the energetic significance of Wauters,pers.comm.). body-mass difference. Proceedings of the Royal Society of Short-term conservation tactics in Britain include short-term London,B. BiologicalSciences268:1731–1736. supplementaryfeeding,Europeanredsquirrelreintroductions,and CABRERA, A. 1905. Las ardillas de Espanã. Boletin de la Real control of S. carolinensis. In the long term, management of forest SociedadEspanõlade HistoriaNatural5:225–231. habitats to favor European red squirrels and deterS. carolinensis CAGNIN,M.,G.ALOISE,F.FIORE,V.ORIOLO,ANDL.A.WAUTERS. is the only option (Gurnell and Pepper 1988, 1993; Pepper and 2000. Habitatuseandpopulationdensityoftheredsquirrel, Patterson 1998). Large conifer forests (2,000–5,000 ha) are ideal Sciurus vulgaris meridionalis, in the Sila Grande mountain but smaller forests (.100 ha) can support viable European red range(Calabria,southItaly).ItalianJournalofZoology67:81– squirrel populations. Clear-cutting should be kept to small areas, 87. and good seed and nest trees left behind where possible (Gurnell CELADA,C.,G.BOGLIANI,A.GARIBOLDI,ANDA.MARACCI. 1994. etal.1997a,2002;Lurzetal.2003;Rushtonetal.1997).Reviews Occupancy of isolated woodlots by the red squirrel Sciurus ofmanagementexistforEuropeanredsquirrelsincaptivity(Dick- vulgarisL. inItaly.BiologicalConservation69:177–183. inson 1995) and in the wild (Gurnell and Lurz1997; Gurnelland CHALINE, J. 1972. 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