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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: [email protected]

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: [email protected]

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.

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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).

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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

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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

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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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1400

140

0

0

60

Go

at

Ol d

Ri v

er

Ch

an

ne

l

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TE

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R

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189

BC 88001

G

MT

RYKERT

Cr

e

e

k

Te e t z e l C r e e k

ki

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l

Cr

ee

k

Mc

Co

mb

Cr

ee

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Ac

or

nC

re

ek

Do

S i m m o n s

Cr

ee

k

C re

ek

B e t t s

Cr

Jo

se

ph

Cr

Ur

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n

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n

Cr

S i m m o n s

C r

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rn

Cr

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ar

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Fr

en

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K

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P o r t h i l l rC

N I C K S

I S L A N D

D a v i d C r e e k

Mo

or e s C r e e k

Mc

Le n n a n C r e e

k

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KO

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BC 78142

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BC 88001 RI

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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).


1 2 3


1 2 3


0 100 200 300 m


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


1 2 3


0 100 200 300 m


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).


1 2 3


1 2 3


0 100 200 300 m



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).


1 2 3


1 2 3


0 100 200 300 m



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).


1 2 3


1 2 3


0 100 200 300 m



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


Dat

e of

Sec

ond

Cap

ture


Dat

e of

Sec

ond

Cap

ture


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


Dat

e of

Sec

ond

Cap

ture


Dat

e of

Sec

ond

Cap

ture


Dat

e of

Sec

ond

Cap

ture


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


Dat

e of

Sec

ond

Cap

ture


Dat

e of

Sec

ond

Cap

ture


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


Dat

e of

Sec

ond

Cap

ture


Dat

e of

Sec

ond

Cap

ture


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

habitat use and movement patterns of northern alligator ... · northern alligator lizards are found...

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