First published online August 3, 2006
Journal of Experimental Biology 209, 3141-3154 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02338
Acclimation to different thermal conditions in a northerly wintering shorebird is driven by body mass-related changes in organ size
François Vézina1,*,
Kirsten M. Jalvingh1,
Anne Dekinga1 and
Theunis Piersma1,2
1 Department of Marine Ecology and Evolution, Royal Netherlands Institute
for Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, Texel, The
Netherlands
2 Animal Ecology Group, Centre for Ecological and Evolutionary Studies,
University of Groningen, PO Box 14, 9750 AA Haren, The Netherlands
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Fig. 1. Average daily ambient temperatures experienced by birds in the variable
(V), warm (W) and cold (C) treatments. Although each data point represents an
average over 24 h, we omitted error bars for clarity. Thick bars represent the
periods of measurements in February and March.
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Fig. 2. Relationship between body mass on the day of ultrasound measurement and
pectoral muscle thickness across treatments in February (A) and in March (B).
Treatments: triangles, cold; squares, variable; circles, warm.
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Fig. 3. Repeatability of basal metabolic rate (BMR) and summit metabolic rate
(Msum) between the months of February and March. The data
are presented as whole-organism BMR (A) and mass-residuals of BMR (B).
Accordingly, values for whole-organism Msum are presented
in C, and mass-residual values are shown in D. Treatments: triangles, cold;
squares, variable; circles, warm.
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Fig. 4. Correlations between basal metabolic rate (BMR) and summit metabolic rate
(Msum). Shown are the analyses on whole-organism values in
February (A) and March (B). Analyses performed on mass-residuals are also
presented for February (C) and March (D). Treatments: triangles, cold;
squares, variable; circles, warm.
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Fig. 5. The effect of the thermal regime (A), overall body mass across treatment
(B) and muscle thickness across treatment (C) on the ambient temperature at
which the birds reached summit metabolic rate (Msum).
Treatments: triangles, cold; squares, variable; circles, warm. Error bars in A
indicate the standard errors. These figures are based on data collected in
March only (see Materials and methods).
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Fig. 6. Graphical representation of the effect of cold acclimation on the
sustainable ambient temperatures. (A) Assuming that a values of 5x BMR
represents an acceptable metabolic ceiling to heat production, and that the
totality of the energy is spent in thermoregulation, then birds acclimated to
our cold condition would have to face a temperature of -50.9°C to reach
their ceilings. Warm-acclimated birds would attain this limit at -31.8°C.
These values correspond to 72.2% and 64.8% of the maximal thermogenic capacity
for cold- and warm-acclimated birds, respectively. Also shown is the
equivalent heat production necessary to face the lowest average ambient
temperature, 3°C, in the south Wadden Sea. (B) The energy expenditure
needed to maintain a normothermic state under various ambient temperature
faced by wintering islandica knots in the Wadden Sea. At 3°C,
thermoregulatory costs accounts for 53.2% and 42.3% of the metabolic ceiling
for warm and cold acclimated birds respectively. At -5°C, birds from the
cold treatment would spend 50.9% of their sustainable energy expenditure in
thermoregulation whereas individuals from the warm treatment would use 63.9%
of sustainable metabolic rate in thermoregulation. These values are based on
conductance estimates for a wind of 1 m s-1 measured by Wiersma and
Piersma (Wiersma and Piersma,
1994 ). See text for more details.
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© The Company of Biologists Ltd 2006
