Document Detail


Longer guts and higher food quality increase energy intake in migratory swans.
MedLine Citation:
PMID:  18662243     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
1. Within the broad field of optimal foraging, it is increasingly acknowledged that animals often face digestive constraints rather than constraints on rates of food collection. This therefore calls for a formalization of how animals could optimize food absorption rates. 2. Here we generate predictions from a simple graphical optimal digestion model for foragers that aim to maximize their (true) metabolizable food intake over total time (i.e. including nonforaging bouts) under a digestive constraint. 3. The model predicts that such foragers should maintain a constant food retention time, even if gut length or food quality changes. For phenotypically flexible foragers, which are able to change the size of their digestive machinery, this means that an increase in gut length should go hand in hand with an increase in gross intake rate. It also means that better quality food should be digested more efficiently. 4. These latter two predictions are tested in a large avian long-distance migrant, the Bewick's swan (Cygnus columbianus bewickii), feeding on grasslands in its Dutch wintering quarters. 5. Throughout winter, free-ranging Bewick's swans, growing a longer gut and experiencing improved food quality, increased their gross intake rate (i.e. bite rate) and showed a higher digestive efficiency. These responses were in accordance with the model and suggest maintenance of a constant food retention time. 6. These changes doubled the birds' absorption rate. Had only food quality changed (and not gut length), then absorption rate would have increased by only 67%; absorption rate would have increased by only 17% had only gut length changed (and not food quality). 7. The prediction that gross intake rate should go up with gut length parallels the mechanism included in some proximate models of foraging that feeding motivation scales inversely to gut fullness. We plea for a tighter integration between ultimate and proximate foraging models.
Authors:
Jan A van Gils; Jan H Beekman; Pieter Coehoorn; Els Corporaal; Ten Dekkers; Marcel Klaassen; Rik van Kraaij; Rinze de Leeuw; Peter P de Vries
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Publication Detail:
Type:  Journal Article     Date:  2008-07-25
Journal Detail:
Title:  The Journal of animal ecology     Volume:  77     ISSN:  1365-2656     ISO Abbreviation:  J Anim Ecol     Publication Date:  2008 Nov 
Date Detail:
Created Date:  2009-01-23     Completed Date:  2009-03-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376574     Medline TA:  J Anim Ecol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1234-41     Citation Subset:  IM    
Affiliation:
Department of Plant-Animal Interactions, Centre for Limnology, Netherlands Institute of Ecology (NIOO-KNAW), AC Nieuwersluis, The Netherlands. jan.van.gils@nioz.nl
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MeSH Terms
Descriptor/Qualifier:
Animal Nutritional Physiological Phenomena
Animals
Anseriformes / anatomy & histology*,  physiology*
Energy Intake / physiology*
Feeding Behavior / physiology*
Gastrointestinal Tract / anatomy & histology*
Gastrointestinal Transit / physiology
Seasons

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