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HABITAT USE AND MOVEMENT
PATTERNS OF NORTHERN ALLIGATOR
LIZARDS AND WESTERN SKINKS IN
SOUTHEASTERN BRITISH COLUMBIA
PREPARED BYPamela L. Rutherford and Patrick T. Gregory
FORColumbia Basin Fish & Wildlife Compensation Program
January 2001
IN PARTNERSHIP WITH
COLUMBIA BASIN
FISH & WILDLIFE
COMPENSATION
PROGRAM
Ministry of Environment,Lands & ParksBC Fisheries
Columbia BasinFish & WildlifeCompensation Program
103 - 333 Victoria Street, Nelson, British Columbia V1L 4K3Phone: (250) 352-6874 Fax: (250) 352-6178
Habitat use and movement patterns of Northern Alligator Lizards (Elgaria
coerulea principis) and Western Skinks (Eumeces skiltonianus skiltonianus)
in Southeastern British Columbia
Pamela L. Rutherford and Patrick T. Gregory
Department of Biology, University of Victoria, Victoria, British Columbia, Canada. V8W 3N5:
Email: prutherf@uvic.ca
Habitat use and movement patterns of Northern Alligator Lizards (Elgaria
coerulea principis) and Western Skinks (Eumeces skiltonianus skiltonianus)
in Southeastern British Columbia
Pamela L. Rutherford and Patrick T. Gregory
Department of Biology, University of Victoria, Victoria, British Columbia, Canada. V8W 3N5:
Email: prutherf@uvic.ca
ABSTRACT
Many reptiles have different requirements for different activities (e.g. hibernation and
nesting/gestation) that may not be satisfied by a single location. Suitable habitat may not only be
limiting, it may be fragmented, making it difficult for animals to move between sites. Our first
objective in this study was to determine the extent to which Northern Alligator Lizards (Elgaria
coerulea principis) and Western Skinks (Eumeces skiltonianus skiltonianus) co-occur, in
southeastern British Columbia, near the northern limit of both species’ ranges. Our second
objective was to determine the characteristics of hibernation and summer sites for both species.
Our third objective was to determine the extent of movement in both species, particularly whether
migration occurs between summer and winter habitats. We used mark-recapture (PIT-tags and
toe-clips) to do this. Both lizard species co-occurred at the same study sites and were found in
approximately the same locations in spring, summer and fall. Thus, hibernation apparently occurs
in the summer habitat and no seasonal migration occurs. In fact, individuals of either species were
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recapturedwithin 10 m (on average)of apreviouscapture.Both lizard specieswererarelyfound
in theopenandmoreoftenunderrocksthanin vegetationor underlogs;they alsoremainedclose
to shrubsandforestedges.Roadsapparentlyarenota majorconcernfor eitherlizard species
becausethey havehighsite-fidelityanddonot makelargemovementsbetweenhibernationor
summersites.Their requirementfor cover meansthatany disturbanceor removal of rocksfrom
their habitatswouldbedetrimentalto bothspecies.
INTRODUCTION
Lackof knowledgeof thenaturalhistoryof aspeciesis oneof thegreatestconstraintsin
conservationplanning.Collectingecologicaldataon reptilespeciesis particularlyimportantas
they have typically attractedlessattentionthanothergroups,resultingin limited dataon their
naturalhistory. To datealmosthalf of the42Canadianreptilespecies(Cook,1984)areof
conservationconcern(1 extirpated,4 endangered,6 threatened,and8 speciesof specialconcern)
accordingto theCommitteeon theStatusof EndangeredWildlife in Canada(COSEWIC,2000),
althoughnotall taxahavebeenevaluated.Thishigh ratio indicatestheimportanceof describing
thenaturalhistoryandhabitatrequirementsof all Canadianreptiles.
Many reptileshavedifferentrequirementsfor hibernationandnesting/gestation(Etheridge
etal., 1983;BurgerandZappalorti,1986;Burgeret al., 1988;PriorandWeatherhead,1996;
Litzgusetal., 1999).Descriptionof thesesitesis of interestto bothconservationbiologistsand
populationbiologists.Identifying hibernationsitesis especiallyimportantin reptilesthat
hibernatecommunally(Gregory,1984;Litzgusetal., 1999)andreturnto thesamehibernation
sitesfrom yearto year(Brown andBrooks,1994;Litzguset al., 1999).Destructionof communal
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hibernationsiteshasoccurredin rattlesnakes(Viperidae)aspartof ‘rattlesnakeround-ups’,
resultingin populationdeclinesor extirpationfrom partsof theUnitedStates(Galliganand
Dunson,1989;Warwick,1990).Hibernationsitedescriptionsarealsousefulfor population
biologistsaspartof determiningwhethera reptilepopulationis limited by availability of suitable
hibernationsites(Gregory,1984).This is particularlyimportantfor northernpopulationsasthe
absenceof availablehibernationsitesmaydictatethenorthernrangelimits for a population.
Populationsarelimited by availablenesting/gestationhabitat.In animalsthatareunable
to reproduceeveryyeardueto energeticlimitations(Aldridge,1979;Luiselli etal., 1996)it is
particularlyimportantthatpregnantfemalescompletegestationandavoid predationwhen
reproductionis attempted.Oviparousreptilesrequirenestsitesthatprovideoptimaltemperatures
andmoisturecontentfor developingembryosyetprotectthemfrom predators.Nestsitesthatfit
thiscriterionmaybelimiting (Cooperet al., 1983;Hecnar,1994).For viviparousreptiles,
selectionof baskingsitesis importantbecausebaskingby gravid femalesmayincreasetherisk of
predation(Huey andSlatkin,1976;Shine,1980;Madsen,1987)dueto their reducedmobility
(Vitt andCongdon,1978;BauwensandThoen,1981;Shine,1980;Seigelet al., 1987;Brodie,
1989;Cooperetal., 1990;Sinervo et al., 1991).
Becausetherequirementsfor hibernatingandreproducingarequitedifferentthey maynot
besatisfiedby a singlelocationandanimalsmayneedto travel longdistancesbetweenthesesites
(Weintraub,1966;GregoryandStewart,1975;Brown andParker,1976;Brown andBrooks,
1994).Movementbetweensitesmaybedifficult if thehabitathasbecomefragmented.Thishas
occurredin many terrestrialhabitats(Diamondet al., 1987;Saunderset al., 1991).Therewill be
additionaldifficulty if therearebarriersbetweenthehibernationhabitatandthesummerhabitat.
Roadsarecommonbarriersthatisolatehabitats,deterthemovementof wildlife andcause
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extensive wildlife mortality (Oxley et al., 1974;Case,1978;DalrympleandReichenbach,1984;
GarlandandBradley, 1984;Mader,1984;BernardinoandDalrymple,1992;RosenandLowe,
1994;Ashley andRobinson,1996;TrombulakandFrissell,2000).In addition,pavedroadsretain
heatandmany snakeswill baskon thepavementincreasingtheir likelihoodof beingkilled
(BernardinoandDalrymple,1992;Ashley andRobinson,1996).Theeffectof roadson small
lizardshasnotbeeninvestigatedandit is importantto determineif roadsrepresentbarriers
betweenhabitatpatchesor if they resultin highmortalitydueto basking,asis thecasewith
snakes.
Hibernationsites,summerhabitat,andbasicmovementbiologyhave notbeendescribed
for theonly two commonlizard speciesfoundin British Columbia,whichcomprisetwo of the
fivenative lizard speciesin Canada:1) theNorthernAlligator Lizard (Elgaria coeruleaprincipis)
or 2) theWesternSkink (Eumecesskiltonianusskiltonianus). Our first objective in this studywas
to determinetheextentto whichNorthernAlligator Lizards(Elgaria coeruleaprincipis) and
WesternSkinks(Eumecesskiltonianusskiltonianus) co-occur, in southeasternBritish Columbia,
nearthenorthernlimit of bothspecies’ranges.Our secondobjectivewasto determinethe
characteristicsof hibernationandsummersitesfor bothspecies.Our third objectivewasto
determinetheextentof movementin bothspecies,particularlywhethermigrationoccursbetween
summerandwinter habitats.We usedmark-recapture(PIT-tagsandtoe-clips)to do this. In
additionto addressingfundamentalquestionsaboutthebiology of theseanimals,our resultsalso
have importantimplicationsfor their management.
4
METHODS
Species Description
TheNorthernAlligator Lizard (Elgaria coeruleaprincipis) is asmall lizardwith a long,slender
bodyandshortlegs. It is brown in color, andfrequentlyhasdarkblotchesthatvarybetweensexes
andpopulations(GregoryandCampbell,1984).It is viviparous,having onelitter peryear;four to
six youngonaverage(Vitt, 1974).It is diurnal,thermoregulatesby basking,andis activeat body
temperaturesrangingfrom 20 to 30˚ C (Vitt, 1973).
TheWesternSkink (Eumecesskiltonianusskiltonianus) is asmallslenderlizard with a
pointedheadandshortlegs. It hasa broadbrownishbanddown its back,flankedby whitestripes.
Theyounghave abright bluetail tip thatfadesasthey age(Gregory andCampbell,1984).They
areoviparousandlay oneclutchperyear. Eggsaredepositedin excavationsdugunderrocksor
othercoverobjects.Clutchsizevariesfrom two to fiveandthefemalefrequentlystayswith the
eggsuntil they hatch.It is diurnalandthermoregulatesby basking(GregoryandCampbell,1984).
Distribution
NorthernAlligator Lizardsarefoundin southernBritish Columbia,southto theSierraNevadaof
California,andeastto thenortherntip of IdahoandnortheasternMontana(Fig. 1). In Canada,the
NorthernAlligator Lizard (Elgaria coeruleaprincipis) occursin southernBritish Columbia,
includingVancouver IslandandtheGulf Islands.Within this rangeit is absentonly from the
southeasterncornerof theprovince(Fig. 2).
TheWesternSkink (Eumecesskiltonianusskiltonianus) is alsolocatedin thesouthernpart
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of British Columbia,southto Baja,CaliforniaandnorthernArizonaandeastto centralUtah(Fig.
3). In British Columbiait is absentfrom thesouthwesterncornerof theprovince,Vancouver
IslandandtheGulf Islands(Fig. 4).
Habitat Preference
NorthernAlligator Lizardscanbefoundin dry woodland,in grassland,alongthebanksof creeks,
andon oceanbeachesup to 1800m. They areoftenassociatedwith rocky outcroppings,talus
slopes,northernandmontaneconiferousforests,andstreams(Fitch,1935;Nussbaumetal., 1983;
Cook,1984;GregoryandCampbell,1984;Good,1988).They arewidespreadin southernBritish
Columbia,inhabitingall four of thesouthernEcoprovinces:SouthernInterior Mountains,
SouthernInterior, CoastandMountainsandGeorgiaDepression.NorthernAlligator Lizardsare
not restrictedto a specifichabitat.In British Columbiathey arearepresentativespeciesin four of
thefourteenbiogeoclimaticzones(MeidingerandPojar,1991):CoastalDouglas-firzone(in
mixedconiferousanddeciduousforests,andGarryOak- Arbutusforests),CoastalWestern
Hemlockzone(in mixedconiferousanddeciduousforests),Interior Douglas-firzone(in riparian
areas,wetlands,meadows,andfloodplains),andInterior Cedar- Hemlockzone(in riparianareas,
wetlands,meadows,andfloodplains).
WesternSkinksalsoarefoundin a varietyof habitats,includingdesertcanyons,open
woodlands,grassland,forestandondry hillsidesup to 2100m in elevation(Nussbaumet al.,
1983;Cook,1984).They aremostcommonlyfoundin open,rocky areaswherethereis lots of
cover in theform of logs,rocks,leaf litter andvegetationandareespeciallycommonalongriver
banks(RodgersandFitch,1947;Tanner,1957,1988;Gregory andCampbell,1984;Morrison
etal., 1999).In British Columbia,they area representativespeciesin threeof thefourteen
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biogeoclimaticzones(MeidingerandPojar,1991):Bunchgrasszone(in riparianareas,wetlands,
meadows,andfloodplains),Interior Douglas-firzone(in riparianareas,wetlands,meadows,and
floodplains),andInterior Cedar- Hemlockzone(in riparianareas,wetlands,meadows,and
floodplains).
Study Site
Thisstudywasconductedduringthesummersof 1996-1998from mid-April to mid-September
on thewestsideof theCrestonValley, 10km westof Creston,British Columbia,Canada(49˚ 6’
N, 116˚ 31’ W; elevation597m; Fig. 5). Meandaily maximumair temperaturesduringApril to
Septemberof 1996rangedfrom 6.5˚ C to 35.0˚ C. Meandaily minimumair temperaturesin the
sametime framerangedfrom -0.6˚ C to 18.3˚ C (EnvironmentCanada,1996).
TheCrestonValley populationsof thesetwo speciesof lizardsarelocatedin thevery dry
warmsubzoneof theInterior Cedar- Hemlockzone.Thissubzoneoccursin a few areasin
extremesoutheasternBritish Columbia,thelargestareabeingtheCrestonValley (Meidingerand
Pojar,1991).Themostcommonvegetationin thissubzoneis (percentagecover is listedin
brackets):Douglas-fir, Pseudotsugamenziesii(26-99);WesternRedcedar, Thujaplicata (11-25);
Snowberry, Synphoricarposalbus(6-10);DouglasMaple,Acerglabrum(6-10);Western
Hemlock,Tsugaheterophylla(6-10);Mallow Ninebark,Physocarpusmalvaceus(2-5); Beaked
Hazelnut,Caryluscornuta(2-5); Mock Orange,Philadelphuslewisii (2-5);PaperBirch, Betula
papyrifera (2-5); Tall OregonGrape,Mahoniaaquifolium(2-5); Thimbleberry, Rubusparviflorus
(2-5); Queen’s Cup,Clintoniauniflora (2-5); Twinflower, Linnaeaborealis(2-5); andUtah
Honeysuckle,Lonicera utahensis(0.1-1)(MeidingerandPojar,1991).
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Mark-recapture
We hand-capturedandtrappedanimalsat four primarystudysites[Pat’sHill (Fig. 6: Group2),
Hydro (Fig. 9: Group1), EastClearing(Fig. 9: Group2), andLonePineHill (Fig. 6: Group4)]
andhand-capturedanimalsat six secondarysites[Dewdney (Fig. 6: Group1), Office(Fig. 9:
Group3), SignSlope(Fig. 9: Group4), Trail (Fig. 9: Group5), Junction(Fig. 6: Group5), and
WestCreston(Fig. 6: Group6)]. In 1998,Pat’sHill wasusedto follow animalswith PIT-tag
implants.All siteswereseparatedfrom eachotherby distancesof 500metersor greater.
Onaverage,theprimarysiteswerevisitedfour timesa yearandthesecondarysiteswere
visitedtwo timesperyearover threeyears(1996-1998).Uponcapturewerecordedthefollowing
data:site,year, groundtemperaturein theopen( ˚ C), temperatureat thecapturesite( ˚ C),
lizard’scaptureposition(openor undercover),distanceto nearestrock >10cm in length(cm),
distanceto nearestshrub>1 m in basediameter(cm),distanceto forestedgeto thenearest5 m,
rockarea(determinedby ascaleddown sketch;cm2), andmeanrock thickness(cm).
TemperaturesweremeasuredusingaSmart2precisionindoor- outdoorthermometerto the
nearest0.1˚ C. Groundtemperatureis theexposedtemperaturein theopen,atgroundlevel, of the
nearestsiteto thecapturedlizard. For lizardscapturedin theopen,it is measuredwherethey
werecaptured.Wegave eachrocka uniquenumberto determineif they wereusedby morethan
onelizard andif lizardsshow sitefidelity.
At eachprimarysitewesetupa portablearrayof traps.All trapnumbers,sessionsand
durationareaverages.In 1997,twelve trapsweresetfor threesessionsof threedaysin length.In
1998,thirty trapsweresetfor four sessionsof fivedaysin length.In bothyears,trapswere
checkedfrom oneto threetimesa daydependingon theweather.
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Thetrapsweremadeof wire-mesh.They were34cm in lengthand10.5cmdiameter. A
wire-meshfunnelwassewn into oneendusing30 lb braidedfishingline. A removablesponge
wasinsertedinto theotherend.Lizardsentereda trapthrougha 3.5cmopeningin thefunneland
wereunableto escape.Trapswerecoveredwith acloth in thespringandfall, anda pieceof wood
in thesummer.
PIT-tags
In 1998,we implantedAVID PIT (Passive IntegratedTransponder)tagsin 13 NorthernAlligator
Lizards(3 adultmale,5 adultfemale,4 juvenilemale,1 juvenilefemale)and6 WesternSkinks(5
adultmaleand1 adultfemale)atonesite(Pat’sHill). Thesetagsdo notappearto affectgrowth
ratesor locomotorperformanceof neonatalsnakes(Keck,1994;Jemisonetal., 1995).Although
RoarkandDorcas(2000)urgedcautionin useof PIT tagsbecauseof their potentialto move
throughthebodyandbeexpelledvia thegut,we nevercapturedany PIT-taggedlizardsthathad
lost their tags.
ThePIT-tagswere14mm by 2.1mm andweigh0.08g. Eachtaghasa circuit, coil and
capacitorsealedin biocompatibleglass.PIT-tagswereimplantedby makingasmall incision(2
mm) in thesideof a lizard andinjectingthetagunderskin,usinga speciallydesignedneedleand
syringe.Animalswereleft to recover for onedayin thelaboratorybeforerelease.All animals
fully recoveredandlaterrecapturesin thefield indicatedcompletehealingof thesmall incision.
Thetagswerereadby passinga readerwithin 18 cmof theanimal.Rockthickness(cm)
measuresin 1996-97indicatedthatonaveragelizardswereunderrockslessthan18cm.
Therefore,we expectedto beableto scancoverobjectsandidentify animalssittingunderthem
without disturbingtheanimals.
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We implantedPIT-tagsfrom May 4-7 andJune14-17.In thespringsessionwescanned
for 480minutesover3 days,but only one(of thesevenimplantedto date)NorthernAlligator
Lizardswasdetectedandtwo (of thefive implantedto date)WesternSkinksweredetected.
Therefore,scanningduringtheremainingthreevisits to thesitewasdoneopportunistically, rather
thanona formalschedule.
Mapping Locations
Broad-scalemapswereconstructedusingaTrimble Geo-ExplorerII GPSunit. Fine-scalemaps
of therocksateachsitewereconstructedby handusinga tapemeasureandcompass.
RESULTS
Species Co-occurrence
NorthernAlligator LizardsandWesternSkinksco-occurredat sevenof tenof thesites(Table1):
Dewdney (Fig. 7), Pat’sHill (Fig. 8), Hydro(Fig. 9: Group1), SignSlope(Fig. 9: Group4),
Office (Fig. 9: Group3), WestCrestonJunction(Fig. 11),andWestCreston(Fig. 12). Northern
Alligator Lizardsweretheonly speciesthatoccurredat theotherthreesites(Table1): LonePine
Hill (Fig. 10),EastClearing(Fig. 9: Group2), andTrail (Fig. 9: Group5). Bothspecies
co-occurredwith NorthernAlligator Lizardsbeingthepredominantspecies(67%or greaterof the
captures)at four sites(Table1): Hydro (Fig. 9: Group1), SignSlope(Fig. 9: Group4), Office
(Fig. 9: Group3) andWestCrestonJunction(Fig. 11). Bothspeciesco-occurredin
approximatelyequalnumbersat two sites(Table1): Dewdney (Fig. 7) andPat’sHill (Fig. 8).
10
WesternSkinkspredominated(79%of thecaptures)atonly onesite(Table1): WestCreston(Fig.
12).
At thesevensiteswherethetwo speciesco-occurred(eitherin equalnumbersor where
onespeciesdominated)therewasno spatialseparationof thetwo speciesandthey were
frequentlyfoundusingthesamerocks,althoughnot together(Fig. 7-9,11,and12). In threeyears
of capturewe neveroncesaw bothspeciesundera rockat thesametime. In fact, for either
species,we foundonly copulatinglizardsor newborn(presumedto befrom thesamelitter)
togetherunderasinglerock.
Hibernation and Summer Sites
NorthernAlligator Lizardscapturedat hibernationsiteswerenearcapturesmadeduringthe
summerat thefour primarystudysites(Fig. 13). A similar patternexistedin WesternSkinksat
theonly primarystudysite(Pat’sHill) wherethey werepresent(Fig. 14). Thissuggeststhatboth
specieswereusingthesamehabitatfor bothhibernationandsummeractivities.
Most NorthernAlligator LizardsandWesternSkinkswerefoundunderrocks(Table2).
NorthernAlligator Lizardswereunderlarger, thickerrocksthanWesternSkinks(t = -1.97,P =
0.050,df = 339;t = -3.282,P = 0.001,df = 306).Both lizardsstayedsimilarly closeto rocks(t =
-1.243,P = 0.214,df = 495),shrubs(t = 0.318,P = 0.751,df = 494)andforestedges(t = 0.451,P
= 0.653,df = 493;Table3).
We comparedassociationswith shrubspeciesbetweenthetwo siteswherethetwo lizard
specieswereabundant(Pat’sHill andDewdney). Thefive mostcommonshrubswerecompared
atPat’sHill andthetop threeatDewdney. Both lizard specieswereassociatedwith similar shrubs
(Pat’sHill: χ2 = 2.75,df = 4, P = 0.60;Dewdney: χ2 = 1.40,df = 2, P = 0.50;Table4).
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Surroundingsubstrateassociations(thetop three)wereonly comparedatPat’s Hill. Both lizard
specieswereassociatedwith similar surroundingsubstrate(χ2 = 3.55,df = 2, P = 0.17;Table5).
All siteswerelocatedon forestedges(Fig. 7-12)andthepredominanttreespecies
differedbetweensites.At Pat’s Hill, whereNorthernAlligator LizardsandWesternSkinkswere
equallyabundant,neitherlizard speciesselectively associatedwith Douglas-firor PonderosaPine
(χ2 = 0.18,df = 1, P = 0.67;Table6). At theothersitewherebothlizard specieswerecommonly
found(Dewdney), thepredominanttreespecieswasDouglas-fir(91%of capturesfor Northern
Alligator Lizardsand100%of capturesfor WesternSkinks).Douglas-firalsopredominatedat the
four siteswhereNorthernAlligator Lizardsweremostabundant[Hydro (100%of captures),
Office (100%of captures),EastClearing(100%of captures)andLonePineHill (99%of
captures)].Themostcommontreespeciesat theonesitewhereWesternSkinksweremost
abundantwasTremblingAspen(96%of capturesfor WesternSkinksand71%of capturesfor
NorthernAlligator Lizards).Theothertreespeciesfoundat this sitewasPonderosaPine.
Neitherlizard specieswascommonlyfoundonroads,eventhoughsix of thetensites
(Hydro,Trail, Office,EastClearing,andWestCrestonJunction)wereborderedononesideby a
road.
Movement Patterns
Distanceswerenotcorrectedfor thetimebetweencapturesastherewasno relationshipbetween
distancemovedanddaysbetweencaptures(Fig. 15). Therefore,raw straight-linedistancewas
usedasthemeasureof thedistancebetweencapturesites.
Twenty-sevenpercent(90 of 334)of all markedNorthernAlligator Lizardswere
recapturedover thethreeyearsandtwenty-fivepercent(25 of 101)of all WesternSkinkswere
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recaptured.Of theserecaptures,neitherNorthernAlligator Lizardsnor WesternSkinkswere
caughtvery far from a previouscapturelocation(Table7). Only onepercentof all Northern
Alligator Lizardsthatwererecapturedmovedfrom onestudysiteto anothersiteover the
three-yearstudy. No individualWesternSkinksweredetectedat asecondsite,althoughneitherof
thetwo mainWesternSkinksiteswerewithin a km of anotherSkinksite.
We compareddistancesbetweencapturelocationswithin thesameyear(1996,1997,or
1998)to thosebetweencaptureyears(1996to 1997,1997to 1998,and1996to 1998).Therewas
nosignificantdifferencein thedistancesregardlessof how far apartin timeNorthernAlligator
Lizards(F5,84= 0.6202,P = 0.6848)or WesternSkinks(F5,19= 0.5441,P = 0.7407)were
captured(Fig. 16).
NorthernAlligator Lizardswereaslikely to makebothshortor longdistancemoves
within or betweenseasons(Fig. 17). This is particularlyevidentfor the1998data,asthe
movementstudywasmoreintensive thatyear. A similar plot of only thewithin-seasondata
shows thatNorthernAlligator Lizardsdid notmakelong-distancemovesfrom hibernationsitesto
summersites(Fig. 18). WesternSkinksshowedsimilar movementpatterns,bothwithin and
betweenseasons(Fig. 19and20)
Adult maleNorthernAlligator Lizardstendedto move greaterdistancesthannewborns,
juvenilesor adultfemales,but thedifferencewasnotsignificant(F3,84= 0.6675,P = 0.5743)
(Fig. 21a).A similar trendwastruefor maleWesternSkinkscomparedto femaleWesternSkinks
but againthedifferencewasnon-significant(t = 0.677,df = 22,P = 0.506)(Fig. 21b).
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Site Fidelity
Sometimesindividualsof bothspecieswerecapturedrepeatedlyat thesamelocation(Northern
Alligator Lizards:9% of 282captures;WesternSkinks:10%of 92captures).Someof these
repeatcaptureswereof thesameanimalrecapturedat thesamelocation[NorthernAlligator
Lizards:7 of the26 (26.9%)repeatcaptures;WesternSkinks;4 of 9 (44.4%)repeatcaptures].In
all otherinstancesdifferentlizardswerecapturedat differenttimesat thesamelocation.
Therewasnodifferencein theareaor thicknessof rocksusedonceversusmore-than-once
for eitherNorthernAlligator Lizards[rock area(t = 0.6117,df = 31.785,P = 0.5451);rock
thickness(t = 0.6714,df = 27.326,P = 0.5076)]or WesternSkinks[rock area(t = 1.2459,df =
8.823,P = 0.2449);rock thickness(t = 1.0124,df = 9.202,P = 0.3372)].Similarly, distanceto the
nearestrock for bothNorthernAlligator Lizards(t = -0.8735,df = 36.305,P = 0.3881)and
WesternSkinks(t = 0.1526,df = 10.945,P = 0.8815);distanceto thenearestshrubfor both
NorthernAlligator Lizards(t = 0.289,df = 26.006,P = 0.7749)andWesternSkinks(t = -1.292,df
= 27.579,P = 0.2071)or distanceto thenearestforestedgefor bothNorthernAlligator Lizards(t
= -0.8374,df = 32.471,P = 0.4085)andWesternSkinks(t = -0.7388,df = 11.269,P = 0.4752)
did notdiffer betweensingle-useor multiple-userocks.
Response to Disturbance
WesternSkinksweremoresecretive thanNorthernAlligator Lizardsasfewerwereseenin the
open,eitherin vegetationor on ahardsubstrate(χ2 = 43.31,df = 5, P<0.001).AlthoughWestern
Skinkswererarelycapturedor sightedin vegetationcomparedto NorthernAlligator Lizards
(Table2), whendisturbedthey typically rantowardsashrubfor cover. In contrast,Northern
14
Alligator Lizardstypically ranto a nearbyrock for cover (personalobservation,P. Rutherford).
DISCUSSION
AlthoughNorthernAlligator LizardsandWesternSkinksarefrequentlyfoundat thesamesitesin
Creston,somesitesaredominatedby onespecies.Why thisshouldbeis not clearbecausewe
have noevidenceof competitive interactionsbetweenthetwo species,althoughthisquestionhas
notbeenaddressedrigorously. Perhapsthepatternof siteoccupationis duesimply to historical
reasons.
NorthernAlligator LizardsandWesternSkinkswerecapturedin thesamelocationsin
spring,summerandfall. Thissuggeststhathibernationandreproductionsitesarein thesame
location.Thishadbeenpreviously reportedfor NorthernAlligator Lizardsby Stewart (1985),
who foundmostrecapturesof individualswithin a10 m radiusof theoriginal capturepoint. This
is in contrastto a previousstudy(Vitt, 1973),in which NorthernAlligator Lizardswere
gregariousaroundlocalizeddensin earlyApril andthenfrom lateApril throughAugustthey
weredispersedaway from thedensites.In addition,individualsof eitherspecieswererecaptured
within 10m (on average)of a previouscapture.Both thesefactorsindicatethata population
requiresarelatively smallareafor persistence.
Both lizard specieswererarelyfoundin theopenandmoreoftenunderrocksthanin
vegetationor underlogs.They rarelystrayedfar from availablecover, remainingclosestto rocks
but typically within 2 m of a shrub. For reptiles,retreatsitescanserve asprotectionfrom lethal
groundtemperaturesandpredators(Huey etal., 1989;DownesandShine,1998).In thesummer,
maximumair temperaturesin Crestoncanreach35˚ C with groundtemperaturesexceeding
15
40˚ C, lethalfor a lizard in theopenin midafternoon.Retreatsitesalsowouldproviderefugefrom
avianpredators.Themainpredatorsof eitherlizard speciesareunknown but NorthernAlligator
Lizardcarcasseshave beenseenon nearbynestboxes;presumablyleft by avian predators.
It alsoappearsthatsomeretreatsitesaremoreimportantthanothers.Althoughwe found
nophysicaldifferencesbetweenthese‘preferred’locationsand‘single-use’locations,it is
possiblethattheformerlocationshadoptimalthermoregulatorypropertiesin additionto their
proximity to availablecover. Movementpatternsalsoindicatedsitefidelity for bothspecies
althoughadultmalesof bothspeciesmovedlongerdistances.Thismayreflectthefact that
nestingWesternSkinksfemalesguardtheir eggs(GregoryandCampbell,1984)andgravid
NorthernAlligator Lizardsfemaleshavereducedmobility (Rutherford,unpublisheddata).
Thisdependenceonspecificretreatsitesmayhave broadeffectson thepopulationbiology
of theseanimals.In areaswherefood is not limiting, theavailability of retreatsitesmay
determinetheupperlimit for speciesabundanceona local scale(Bustard,1969,1970).For
retreat-siteavailability to belimiting retreatsitesmustbevital to thebiology of theanimaland
theremustbea limit on thenumberof individual lizardsableto useeachsitesimultaneously. Use
of a rockby morethanoneNorthernAlligator Lizardor WesternSkink wasrarein thisstudy,
regardlessof thesizeof therock.
Thisnecessityfor availablecovermeansthatany disturbanceor removal of rocksin the
areawouldbedetrimentalto bothspecies.Rockcollectingis thoughtto negatively impactVelvet
Geckos(Oedura lesueurii) (SchlesingerandShine,1994)andBroad-headedSnakes(Shineetal.,
1998)in southernAustralia.NorthernAlligator LizardsandWesternSkinksaresimilar to these
reptilesin thatthey rely heavily on retreatsitesandshow somesitefidelity. Bothof thesefeatures
makethemsusceptibleto retreat-sitedisturbance.
16
Althoughbothlizardsweremostcommonlycapturedunderrocksthey remainedcloseto
nearbyshrubs.In addition,disturbedWesternSkinkspreferentiallyrantowardsshrubsfor cover.
NorthernAlligator LizardsandWesternSkinksweremostfrequentlyfoundnearestfour shrub
types:Mallow NineBark (Physocarpusmalvaceus), OceanSpray(Holodiscusdiscolor),
Snowberry(Symphorocarposalbus), andMock Orange(Philadelphuslewsii). Thereis no
differencein theshrubtypesselectedby thetwo lizardspecies.Proximity to theseshrubtypes
merelyreflectstheir availability at thesite(MeidingerandPojar,1991;Parishetal., 1996).All
four of theseshrubsaredenseandprovidecover closeto thegroundallowing thelizardsto
disappeareasilyinto thevegetation.Both lizardspeciesareinsectivores(GregoryandCampbell,
1984)andalsomayusetheshrubsfor foraging.Thetwo lizard speciesaremostoftenfoundin
grassor mossassurroundingsubstrate,whichmayalsoprovidecover. Bothshrubsand
surroundingsubstrateappearimportantto theselizard species.
Theassociationof NorthernAlligator LizardsandWesternSkinkswith forestsis unclear.
All siteswerein forestclearingsbut thelizardsmaynothave beenutilizing theforests.Northern
Alligator Lizardssometimesarecapturedwithin forests(GregoryandCampbell,1984),but they
aremostcommonlyseenin clearings.Thismayin partbedueto thedifficulty of seeingand
capturinga lizard in theforestcomparedto in anopenclearing.Theconsistentcaptureand
recaptureof bothspeciesin theclearingssuggeststhatevenif they wereventuringinto theforests
they still returnedto theclearing.An intensive movementstudywouldneedto beconductedto
determinetheirassociationwith forests.
17
Management Recommendations
Both lizardspeciesarewidely distributedthroughoutwesternCanadaandtheUnitedStateswhich
makesthemlessvulnerableto extinction. Nonethelesstherehave beenfew naturalhistorystudies
of eitherspeciesandnostudiesevaluatingwhetherpopulationsaredecreasingin sizeor
disappearing.Both lizardsrequirerockandvegetative coveranddisturbanceor removal of this
cover will makethemvulnerableto predation.
Both lizardsrespondquickly to passersbyandrun to availablecover wherethey remain
for anextendedperiod.Only copulatinglizardswereunresponsive to humanpresence,even
toleratingbeingpickedup while they remainedtogether. Hiking pathsthroughprimelizard
habitatprobablywouldbedetrimentalto lizard populationsasthey wouldnotallow animalsto
baskwithoutdisturbance.In particular, gravid femaleNorthernAlligator Lizardswouldbe
consistentlydisturbedwhile trying to maintainembryosatoptimaldevelopmentaltemperatures.
Roadsapparentlyarenota majorconcernfor eitherlizard speciesbecausethey havehigh
site-fidelityanddonotmakelargemovementsbetweenhibernationor reproductionsites.In
addition,they arenotattractedto roadsasheatsources.However, it is possiblethatroadsserveas
barriersbetweenpopulations.This resultsin unconnectedpopulations,ultimatelylimiting gene
flow andeliminatingcolonizationof new areas.Thishasnotbeenshown in lizardsbut hasbeen
observedin populationsof smallandmedium-sizedmammalsandcarabidbeetles(Oxley etal.,
1974;Mader,1984).Knowledgeof thebreedingbiology anddispersalpatternsof theselizardsis
necessaryto determineif this is a concern.
18
Acknowledgments
Theauthorsthankthestaff at theCrestonValley Wildlife ManagementArea(B. Stushnoff, A. de
Jager, G. Cooper, D. Bjarnason,andB. Bruns),ColumbiaBasinFishandWildlife Program(I.
Parfitt andJ.Krebs)andtheSimonFraserUniversityField Station(R. Ydenberg) for logistical
support.Field assistancewasprovidedby D. Hoysak,J.Rutherford,M. BeaucherandM. Bowen.
Thisstudywasfinanciallysupportedby theColumbiaBasinTrustandanN.S.E.R.Coperating
grantto P.T.G.
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23
TABLE 1. Sizesof thetenstudysitesandtotal numberof capturesof NorthernAlligator Lizards(Elgaria coeruleaprincipis) andWesternSkinks(Eumecesskiltonianusskiltonianus).
Site Size (m2) E. coerulea E. skiltonianus TOTAL(N) (%) (N) (%)
PrimaryPat’sHill 22 500 61 61 39 39 100Hydro 60 000 51 93 4 7 55EastClearing 30 000 50 100 0 0 50LonePineHill 52 500 65 100 0 0 65
SecondaryDewdney 70 000 36 59 25 41 61Office 90 000 47 94 3 6 50SignSlope 10 000 3 75 1 25 4Trail 2 500 6 100 0 0 6Junction 1 250 4 67 2 33 6WestCreston 22 500 7 21 27 79 34Total 334 100 100 100 435
24
TABLE 2. Locationsof all captured(includingrecaptures)andsighted(not captured)a)NorthernAlligator Lizards(Elgaria coeruleaprincipis) andb) WesternSkinks(Eumecesskiltonianusskiltonianus) from CVWMA, Creston,British Columbiacollectedin 1996-1998.
A
Location Captured Sighted Total(N) (%) (N) (%) (N) (%)
Underrock 271 61 47 34 318 55In vegetation 59 13 21 15 80 14Ondirt/rock 27 6 24 18 51 9Underlog 4 1 1 1 5 1Onroad 2 0.5 0 0 2 0.3Unknown 79 18 42 31 121 21Total 442 100 137 100 579 100
B
Location Captured Sighted Total(N) (%) (N) (%) (N) (%)
Underrock 112 83 55 60 167 74In vegetation 2 1 5 5 7 3Ondirt/rock 1 1 2 1 3 1Underlog 0 0 0 0 0 0Onroad 0 0 0 0 0 0Unknown 19 14 29 32 48 21Total 135 100 91 100 226 100
25
TABLE 3. Summarystatisticsfor proximity to cover, andcover objectsizeof a)NorthernAlligator Lizards(Elgaria coeruleaprincipis)andb) WesternSkinks(Eumecesskiltonianusskiltonianus) from CVWMA, Creston,British Columbiacollectedin 1996-1998.
A
Variable N Min Max Mean SE
Distanceto rock (cm) 380 0 520 23.7 3.0Distanceto shrub(cm) 379 0 4400 177.7 14.7Distanceto forestedge(m) 378 0 100 17.3 0.7Rocksize(cm2) 248 82 5500 916.4 42.1Rockthickness(cm) 248 1 34 8.6 0.3
B
Variable N Min Max Mean SE
Distanceto rock (cm) 117 0 198 16.7 3.1Distanceto shrub(cm) 117 0 3000 184.7 27.3Distanceto forestedge(m) 117 0 80 18.0 1.2Rocksize(cm2) 93 96 3360 756.0 71.0Rockthickness(cm) 93 1 22 6.7 0.4
26
TABLE 4. Speciesof nearestshrubof capturedNorthernAlligator Lizards(Elgaria coeruleaprincipis) andWesternSkinks(Eumecesskiltonianusskiltonianus) from a)Pat’sHill andb)Dewdney on theCVWMA, Creston,British Columbiacollectedin 1996-1998.
A
Shrub Type E. coerulea E. skiltonianus(N) (%) (N) (%)
Mallow NineBark (Physocarpusmalvaceus) 23 28 12 20OceanSpray(Holodiscusdiscolor) 19 23 13 22Snowberry(Symphorocarposalbus) 15 18 10 17Mock Orange(Philadelphuslewsii) 9 11 9 15Rose(variousspp.) 8 10 10 17Other 9 11 6 10Total 83 100 60 100
B
Shrub Type E. coerulea E. skiltonianus(N) (%) (N) (%)
Mallow NineBark (Physocarpusmalvaceus) 4 12 8 38OceanSpray(Holodiscusdiscolor) 6 18 5 24Mock Orange(Philadelphuslewsii) 6 18 5 24Snowberry(Symphorocarposalbus) 8 24 1 5Rose(variousspp.) 2 6 2 10Other 8 24 0 0Total 34 100 21 100
27
TABLE 5. Speciesof immediatelysurroundingsubstrateof capturedNorthernAlligator Lizards(Elgaria coeruleaprincipis) andWesternSkinks(Eumecesskiltonianusskiltonianus) from Pat’sHill on theCVWMA, Creston,British Columbiacollectedin 1996-1998.
Substrate Type E. coerulea E. skiltonianus(N) (%) (N) (%)
Grass(variousspp.) 32 40 40 67Moss(variousspp.) 20 25 11 18Dirt 7 9 6 10Fern(variousspp.) 5 6 2 3OregonGrape(Mahoniaaquifolium) 8 10 0 0Needles(variousspp.) 7 9 1 2Other 2 2 0 0Total 81 100 60 100
TABLE 6. Speciesof treesin thenearestforestedgeof capturedNorthernAlligator Lizards(Elgaria coeruleaprincipis) andWesternSkinks(Eumecesskiltonianusskiltonianus) from Pat’sHill on theCVWMA, Creston,British Columbiacollectedin 1996-1998.
Tree Type E. coerulea E. skiltonianus(N) (%) (N) (%)
PonderosaPine(Pinusponderosa) 52 63 34 57Douglas-fir(Pseudotsugamenziesii) 31 37 25 42Rocky MountainJuniper(Juniperusscopulorum) 0 0 1 2Total 83 100 135 100
28
TABLE 7. Summaryof distance(m) betweencapturelocationsfor NorthernAlligator Lizards(Elgaria coeruleaprincipis) andWesternSkinks(Eumecesskiltonianusskiltonianus) fromCVWMA, Creston,British Columbiacollectedin 1996-1998.
Statistic E. coerulea E. skiltonianus(All) (Within Site) (All)
Minimum 0 0 0Maximum 500 53 61.4Mean 16.1 10.7 8.0StandardError 5.56 1.18 2.67Median 7.0 6.7 3.6N 90 89 25
29
FIG. 1. Distribution of Northern Alligator Lizards (Elgaria coerulea principis) in North America(from Stebbins, 1966).
30
Elgaria coerulea coeruleusElgaria coerulea shastensisElgaria coerulea principisElgaria coerulea palmeri
FIG. 2. Distribution of Northern Alligator Lizards (Elgaria coerulea principis) in BritishColumbia (from Orchard, 1988).
31
FIG. 3. Distribution of Western Skinks (Eumeces skiltonianus skiltonianus) in North America(from Stebbins, 1966).
32
Eumeces skiltonianus skiltonianusEumeces skiltonianus utahensisEumeces skiltonianus interparietalis
FIG. 4. Distribution of Western Skinks (Eumeces skiltonianus skiltonianus) in British Columbia(from Orchard, 1988).
33
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1 100
11001200
1 200
00
1400
140
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60
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54 30 000m N
54 35 000m N
54 40 000m N
54 45 000m N
5 25 000m E 5 30 000m E
Group 4
Group 3
Group 6
Group 2
Group 1
Group 5
Northern Alligator Lizard Capture
Western Skink Capture
CVWMA Boundary
0 1 2 3 4 5 km
Scale 1:75,000 - Projection UTM Zone 11 - Datum NAD83Columbia Basin Fish and Wildlife Compensation Program GIS -- October 16, 2000
35
FIG. 6. The 10 study sites with the CVWMA: Dewdney (Group 1), Pat's Hill (Group 2), Balance Rock (Group 3; contains Hydro, East Clearing, Office, Sign Slope, Trail), Lone Pine Hill (Group 4), West Creston Junction (Group 5), and West Creston (Group 6). Locations of Northern Alligator Lizards (Elgaria coerulea principis) and Western Skinks (Eumeces skiltonianus skiltonianus) are shown.
54 44 000m N
54 44 200m N
54 44 400m N
54 44 600m N5 25 800m E 5 26 000m E 5 26 200m E 5 26 400m E
FIG. 7. Locations and numbers of Northern Alligator Lizards ( Elgaria coerulea principis )and Western Skinks ( Eumeces skiltonianus skiltonianus ) at Dewdney (Group 1 on Fig. 6).
Northern Alligator Lizards (No. captured at location by class)
1 2 3
Western Skinks (No. captured at location by class)
1 2 3
Number of Captures: Class 1 = 0-5; Class 2 = 6-10; Class 3 = > 10
0 100 200 300 m
Scale: 1:5000Map Projection: UTM Zone 11
Datum: NAD 83CBFWCP GIS
October 16, 2000
36
54 43 000m N
54 43 200m N
54 43 400m N
54 43 600m N
54 43 800m N
54 44 000m N5 25 600m E 5 25 800m E 5 26 000m E 5 26 200m E
FIG. 8. Locations and numbers of Northern Alligator Lizards ( Elgaria coerulea principis )and Western Skinks ( Eumeces skiltonianus skiltonianus ) at Pat's Hill (Group 2 on Fig. 6).
Northern Alligator Lizards (No. captured at location by class)
1 2 3
Western Skinks (No. captured at location by class)
1 2 3
Number of Captures: Class 1 = 0-5; Class 2 = 6-10; Class 3 = > 10
0 100 200 300 m
Scale: 1:5000Map Projection: UTM Zone 11
Datum: NAD 83
CBFWCP GISOctober 16, 2000
37
54 40 800m N
54 41 000m N
54 41 200m N
54 41 400m N
54 41 600m N
54 41 800m N
54 42 000m N
5 26 000m E 5 26 200m E 5 26 400m E 5 26 600m E 5 26 800m E
2
3
4
5
1
FIG. 9. Locations and numbers of Northern Alligator Lizards ( Elgaria coerulea principis )and Western Skinks ( Eumeces skiltonianus skiltonianus ) at Balance Rock (Group 3 on Fig. 6).The following sub-sites are indicated: Hydro, (Group 1); East Clearing, (Group 2); Office, (Group 3);Sign Slope, (Group 4); and Trail, (Group 5)Northern Alligator Lizards (No. captured at location by class)
1 2 3
Western Skinks (No. captured at location by class)
1 2 3
Number of Captures: Class 1 = 0-5; Class 2 = 6-10; Class 3 = > 10
0 100 200 300 m
Scale: 1:7500Map Projection: UTM Zone 11
Datum: NAD 83
CBFWCP GISOctober 17, 2000
38
54 39 600m N
54 39 800m N
54 40 000m N
54 40 200m N
54 40 400m N5 26 800m E 5 27 000m E 5 27 200m E 5 27 400m E
FIG. 10. Locations and numbers of Northern Alligator Lizards ( Elgaria coerulea principis )and Western Skinks ( Eumeces skiltonianus skiltonianus ) at Lone Pine Hill (Group 4 on Fig. 6).
Northern Alligator Lizards (No. captured at location by class)
1 2 3
Western Skinks (No. captured at location by class)
1 2 3
Number of Captures: Class 1 = 0-5; Class 2 = 6-10; Class 3 = > 10
0 100 200 300 m
Scale: 1:5000Map Projection: UTM Zone 11
Datum: NAD 83CBFWCP GIS
October 16, 2000
39
54 36 000m N
54 36 200m N
54 36 400m N
54 36 600m N5 29 000m E 5 29 200m E 5 29 400m E 5 29 600m E
FIG. 11. Locations and numbers of Northern Alligator Lizards ( Elgaria coerulea principis )and Western Skinks ( Eumeces skiltonianus skiltonianus ) at West Creston Junction (Group 5 on Fig. 6).
Northern Alligator Lizards (No. captured at location by class)
1 2 3
Western Skinks (No. captured at location by class)
1 2 3
Number of Captures: Class 1 = 0-5; Class 2 = 6-10; Class 3 = > 10
0 100 200 300 m
Scale: 1:5000Map Projection: UTM Zone 11
Datum: NAD 83CBFWCP GIS
October 16, 2000
40
54 30 600m N
54 30 800m N
54 31 000m N
54 31 200m N
54 31 400m N5 31 000m E 5 31 200m E 5 31 400m E 5 31 600m E
FIG. 12. Locations and numbers of Northern Alligator Lizards ( Elgaria coerulea principis )and Western Skinks ( Eumeces skiltonianus skiltonianus ) at West Creston (Group 6 on Fig. 6).
Northern Alligator Lizards (No. captured at location by class)
1 2 3
Western Skinks (No. captured at location by class)
1 2 3
Number of Captures: Class 1 = 0-5; Class 2 = 6-10; Class 3 = > 10
0 100 200 300 m
Scale: 1:5000Map Projection: UTM Zone 11
Datum: NAD 83CBFWCP GIS
October 16, 2000
41
0 50 100 150
050
100
150
X Coordinate (m)
Y C
oord
inat
e (m
)
A
0 50 100 150
050
100
150
X Coordinate (m)
Y C
oord
inat
e (m
)
0 100 200 300 400
010
020
030
040
0X Coordinate (m)
Y C
oord
inat
e (m
)
B
0 100 200 300 400
010
020
030
040
0X Coordinate (m)
Y C
oord
inat
e (m
)
0 100 200 300 400
010
020
030
040
0
X Coordinate (m)
Y C
oord
inat
e (m
)
C
0 100 200 300 400
010
020
030
040
0
X Coordinate (m)
Y C
oord
inat
e (m
)
0 100 200 300 400
010
020
030
040
0
X Coordinate (m)
Y C
oord
inat
e (m
)
D
0 100 200 300 400
010
020
030
040
0
X Coordinate (m)
Y C
oord
inat
e (m
)
FIG. 13. Hibernation(closedcircle)andsummersites(opencircle) for NorthernAlligatorLizards(Elgaria coeruleaprincipis) at four primarysites:a)Pat’s Hill, b) BalanceRock(Hydro),c) BalanceRock(EastClearing),andd) LonePineHill.
42
0 50 100 150
050
100
150
X Coordinate (m)
Y C
oord
inat
e (m
)
0 50 100 150
050
100
150
X Coordinate (m)
Y C
oord
inat
e (m
)
FIG. 14. Hibernation(closedcircle)andsummersites(opencircle) for WesternSkinks(Eumecesskiltonianusskiltonianus) atPat’s Hill.
43
0 10 20 30 40 50 60 70
020
040
060
080
0
Distance between capture sites (m)
Day
s be
twee
n ca
ptur
es A
0 10 20 30 40 50 60 70
020
040
060
080
0
Distance between capture sites (m)
Day
s be
twee
n ca
ptur
es B
FIG. 15. Daysbetweencapturesitesanddistancetraveled(m) by a)NorthernAlligator Lizards(Elgaria coeruleaprincipis) andb) WesternSkinks(Eumecesskiltonianusskiltonianus) fromCVWMA, Creston,British Columbiacollectedin 1996-1998.Oneoutlier, anadultmaleNorthernAlligator Lizard whowasrecapturedmorethan500m from hisoriginal captureafter330days,wasomittedfrom theplot.
44
1020
3040
50
Capture and Recapture Years
Dis
tanc
e m
oved
(m
)
1996 1997 1998 96 & 97 97 & 98 96 & 98
A
(4) (7)(35)
(9)(27)
(8)
05
1015
20
Capture and Recapture Years
Dis
tanc
e m
oved
(m
)
1996 1997 1998 96 & 97 97 & 98 96 & 98
B
(2)
(5)
(11)
(2)
(4)
(1)
FIG. 16. Meandistanceandstandarderrorbarsbetweencapturelocationswithin a yearor indifferentyearsfor a)NorthernAlligator Lizards(Elgaria coeruleaprincipis) andb) WesternSkinks(Eumecesskiltonianusskiltonianus) from CVWMA, Creston,British Columbiacollectedin 1996-1998.Samplesizesaregivenin brackets.
45
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
April 96 Sept 96 April 97 Sept 97 April 98 Sept 98
Apr
il 96
Sep
t 96
Apr
il 97
Sep
t 97
Apr
il 98
Sep
t 98
<10 m 10−25 m 25−50 m
>50 m
FIG. 17. Distancebetweenlocationof first captureandlocationof secondcapturefor NorthernAlligator Lizards(Elgaria coeruleaprincipis) from CVWMA, Creston,British Columbiacollectedin 1996-1998.
46
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
April 1 May 1 June 1 July 1 Aug 1 Sept 1 Oct 1
Apr
il 1
May
1Ju
ne 1
July
1A
ug 1
Sep
t 1O
ct 1
<10 m 10−25 m 25−50 m
FIG. 18. Distancebetweenlocationof first captureandlocationof secondcapturewithin oneseasonfor NorthernAlligator Lizards(Elgaria coeruleaprincipis) from CVWMA, Creston,British Columbiacollectedin 1996-1998.
47
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
April 96 Sept 96 April 97 Sept 97 April 98 Sept 98
Apr
il 96
Sep
t 96
Apr
il 97
Sep
t 97
Apr
il 98
Sep
t 98
<5 m 5−10 m >10 m
FIG. 19. Distancebetweenlocationof first captureandlocationof secondcapturefor WesternSkinks(Eumecesskiltonianusskiltonianus) from CVWMA, Creston,British Columbiacollectedin 1996-1998.
48
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
Date of First Capture
Dat
e of
Sec
ond
Cap
ture
April 1 May 1 June 1 July 1 Aug 1 Sept 1 Oct 1
Apr
il 1
May
1Ju
ne 1
July
1A
ug 1
Sep
t 1O
ct 1
<5 m 5−10 m >10 m
FIG. 20. Distancebetweenlocationof first captureandlocationof secondcapturewithin oneseasonfor WesternSkinks(Eumecesskiltonianusskiltonianus) from CVWMA, Creston,BritishColumbiacollectedin 1996-1998.
49
010
2030
4050
Sex / Age Categories
Dis
tanc
e be
twee
n ca
ptur
es (
m)
Newborn Juvenile Adult Female Adult Male
A
(9)
(43)(58)
(62)
05
1015
Sex
Dis
tanc
e be
twee
n ca
ptur
es (
m)
Female Male
B
(7)
(34)
FIG. 21. Meandistanceandstandarderrorbarsbetweencapturelocationsfor a)newborn,juvenile,adultfemaleandadultmaleNorthernAlligator Lizards(Elgaria coeruleaprincipis) andb) femaleandmaleWesternSkinks(Eumecesskiltonianusskiltonianus) from CVWMA, Creston,British Columbiacollectedin 1996-1998.Samplesizesaregivenin brackets.
50
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