Energetic mediation of natal dispersal behaviour in North American red squirrels (Tamiasciurus hudsonicus)

Objectives energetic challenge energetic challenge resource availability natal dispersal philopatry

Objectives FOOD MANIPULATION SUPPLEMENTCONTROL LITTER SIZE MANIPULATION +2 JUVENILES n=20 -2 JUVENILES n=20

Food manipulation fall 2003 to spring 2004 (before juvenile emergence) fall 2003 to spring 2004 (before juvenile emergence) short- and long-term prenatal effects short- and long-term prenatal effects FOOD MANIPULATION LITTER SIZE MANIPULATION SUPPLEMENTCONTROL +2 JUVENILESn=20 -2 JUVENILESn=20

Litter size manipulation postnatal effects postnatal effects donor litter -2 donor litter -2 recipient litter +2 recipient litter +2 FOOD MANIPULATION LITTER SIZE MANIPULATION SUPPLEMENTCONTROL +2 JUVENILESn=20 -2 JUVENILESn=20

Response Variation in natal dispersal behaviour inter- vs. intranest inter- vs. intranest inter- vs. intrafamily inter- vs. intrafamily

Measurements VARIABLEINTERVAL growth rate growth rate energy expenditure energy expenditure settlement success settlement success dispersal distance dispersal distance future survival future survival behaviour behaviour emergence emergence weaning weaning territorial forays territorial forays settlement settlement late summer/early fall late summer/early fall

daily energy expenditure (DEE) daily energy expenditure (DEE) –Doubly-labeled water technique (Speakman 1997) –O 18 and H 2 isotopes} 2 H 2 O 18 –two blood samples –CO 2 production E expenditure Energy expenditure

Settlement success territorial behaviours territorial behaviours Dispersal distance natal midden acquired midden natal midden acquired midden Future survival post-settlement post-settlement

Telemetry

Behaviour focal sampling focal sampling –postnatal stages –location –dispersal behaviour –interactions –activity –sex bias

Summary Objective – energetic challenge resource availability natal dispersal philopatry Variable+2/control – – 2/supplement growth rate –+ E expenditure –+ settlement success –+ dispersal distance –+ future survival –+ behavioural dominance –+ dispersal<> philopatry><