Energetic mediation of Energetic mediation of natal dispersal natal dispersal

behaviour in North behaviour in North American red squirrels American red squirrels

((Tamiasciurus Tamiasciurus hudsonicushudsonicus))

ObjectivesObjectives

energetic challengeenergetic challenge

resource resource availabilitavailabilit

yy

natal natal dispersaldispersal

philopatryphilopatry

Objectives

FOOD MANIPULATION

SUPPLEMENT CONTROL

LITTER SIZE MANIPULATIO

N

+2 JUVENILES n=20 n=20

-2 JUVENILES n=20 n=20

Food manipulationFood manipulation

fall 2003 to spring 2004 (before juvenile fall 2003 to spring 2004 (before juvenile emergence)emergence)

short- and long-term prenatal effectsshort- and long-term prenatal effects

FOOD MANIPULATION

LITTER SIZE MANIPULATION

SUPPLEMENT CONTROL

+2 JUVENILES n=20 n=20

-2 JUVENILES n=20 n=20

Litter size manipulationLitter size manipulation postnatal effectspostnatal effects donor litter -2donor litter -2 recipient litter +2recipient litter +2

FOOD MANIPULATION

LITTER SIZE MANIPULATION

SUPPLEMENT CONTROL

+2 JUVENILES n=20 n=20

-2 JUVENILES n=20 n=20

ResponseResponse

Variation in natal dispersal behaviourVariation in natal dispersal behaviour

inter- vs. intranestinter- vs. intranest inter- vs. intrafamilyinter- vs. intrafamily

MeasurementsMeasurements

VARIABLEVARIABLE INTERVALINTERVAL

growth rategrowth rate energy expenditureenergy expenditure settlement successsettlement success dispersal distancedispersal distance future survivalfuture survival behaviourbehaviour

emergenceemergence weaningweaning territorial foraysterritorial forays settlementsettlement late summer/early late summer/early fallfall

daily energy expenditure (DEE)daily energy expenditure (DEE)

– Doubly-labeled water technique Doubly-labeled water technique (Speakman 1997)(Speakman 1997)

– OO1818 and H and H22 isotopes} isotopes} 22HH22OO1818 – two blood samplestwo blood samples– COCO22 production E expenditure production E expenditure

Energy expenditureEnergy expenditure

Settlement successSettlement success territorial behavioursterritorial behaviours

Dispersal distanceDispersal distance natal midden acquired middennatal midden acquired midden

Future survivalFuture survival post-settlementpost-settlement

TelemetryTelemetry

BehaviourBehaviour

focal samplingfocal sampling

– postnatal stagespostnatal stages– locationlocation– dispersal behaviourdispersal behaviour– interactionsinteractions– activityactivity– sex biassex bias

SummarySummaryObjective – energetic challengeObjective – energetic challenge

resource resource availabilityavailability

natal natal dispersaldispersal

philopatryphilopatryVariableVariable +2/control+2/control –– 2/supplement

growth rategrowth rate – – ++

E expenditureE expenditure –– ++

settlement successsettlement success –– ++

dispersal distancedispersal distance –– ++

future survivalfuture survival –– ++

behavioural behavioural dominancedominance

–– ++

dispersaldispersal << >>

philopatryphilopatry >> <<