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

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

• energetic challenge

resource availability natal dispersal philopatry
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Objectives FOOD MANIPULATION FOOD MANIPULATION
SUPPLEMENT CONTROL
LITTER SIZE MANIPULATION 2 JUVENILES n20 n20
LITTER SIZE MANIPULATION -2 JUVENILES n20 n20
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Food manipulation

• fall 2003 to spring 2004 (before juvenile
  emergence)
• short- and long-term prenatal effects

FOOD MANIPULATION FOOD MANIPULATION
LITTER SIZE MANIPULATION SUPPLEMENT CONTROL
2 JUVENILES n20 n20
-2 JUVENILES n20 n20
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Litter size manipulation

• postnatal effects
• donor litter -2
• recipient litter 2

FOOD MANIPULATION FOOD MANIPULATION
LITTER SIZE MANIPULATION SUPPLEMENT CONTROL
2 JUVENILES n20 n20
-2 JUVENILES n20 n20
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Response

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

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

• daily energy expenditure (DEE)
• Doubly-labeled water technique (Speakman 1997)
• O18 and H2 isotopes 2H2O18
• two blood samples
• CO2 production E expenditure

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

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Telemetry
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Behaviour

• focal sampling
• postnatal stages
• location
• dispersal behaviour
• interactions
• activity
• sex bias

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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 lt gt
philopatry gt lt