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Red knots give up flight capacity and defend food processing capacity during winter starvation

  1. MAURINE W. DIETZ1,*,
  2. THEUNIS PIERSMA1,2

Article first published online: 7 JUN 2007

DOI: 10.1111/j.1365-2435.2007.01290.x

Issue

Functional Ecology

Functional Ecology

Volume 21, Issue 5, pages 899–904, October 2007

Additional Information

How to Cite

DIETZ, M. W. and PIERSMA, T. (2007), Red knots give up flight capacity and defend food processing capacity during winter starvation. Functional Ecology, 21: 899–904. doi: 10.1111/j.1365-2435.2007.01290.x

Author Information

  1. 1

    Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, PO Box 14, 9750 AA Haren, The Netherlands,

  2. 2

    Department of Marine Ecology and Evolution, Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, Texel, The Netherlands

* †Author to whom correspondence should be addressed. E-mail: M.W.Dietz@rug.nl

Publication History

  1. Issue published online: 7 JUN 2007
  2. Article first published online: 7 JUN 2007
  3. Received 18 December 2006; revised 5 April; accepted 20 April 2007; Editor: TonyWilliams

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Keywords:

  • body composition;
  • gizzard;
  • intestines;
  • pectoral muscle;
  • shorebird

Summary

  • 1
    During the last phase of starvation, animals depend mainly on protein breakdown. All organs are a potential protein source. Do starving animals prevent particular organs from being catabolized in order to defend certain functions? In this study we investigated if starving birds maintain locomotion and digestion capacities, both essential for the recovery process.
  • 2
    We compared body composition data of healthy wintering and winter-starved red knots (Calidris canutus islandica), a long-distance migrating shorebird that breeds on High Arctic tundra in Canada and Greenland, and winters in temperate coastal areas such as the Wadden Sea and the British estuaries. Throughout the wintering period they eat hard-shelled molluscs ingested whole.
  • 3
    Our results showed that winter-starved knots had catabolized 60·5% of their pectoral muscles. This was much more than the decrease in overall body mass (32·5%). As a result, their flight capacities will have been reduced.
  • 4
    Winter-starved knots defended the muscular gizzard, which lost only 21·2% of its mass. As knots crack the ingested shellfish with their gizzard, the organ is essential for food processing. The intestines and liver were not defended; their atrophy equalled that of the pectoral muscles (60·6% and 61·3%, respectively).
  • 5
    Comparison with data from the literature led to the conclusion that starving birds only defend organs that are essential to either obtain or process food. These organs are maintained at the minimal level of normal capacity. Other organs decrease below this level and may lose much of their functional capacity.
  • 6
    Even in near-death situations, with low fitness prospects, organisms show interpretably adaptive changes in organ size.
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