Carbohydrate absorption by blackcap warblers (Sylvia atricapilla) changes during migratory refuelling stopovers

C. R. Tracy, T. J. McWhorter, M. S. Wojciechowski, B. Pinshow, W. H. Karasov

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Passerine birds migrating long distances arrive at stopover sites to refuel having lost as much as 50% of their initial body mass (mb), including significant losses to digestive organs that may serve as a reservoir of protein catabolised for fuel during flight. Birds newly arrived at a stopover show slow or no mb gain during the initial 2-3 days of a stopover, which suggests that energy assimilation may be limited by reduced digestive organs. Measurements of migrants and captive birds subjected to simulated migratory fasts have shown reductions in intestine mass, morphological changes to the mucosal epithelium, and reductions in food intake and assimilation rate upon initial refeeding. We found that blackcaps (Sylvia atricapilla, Linnaeus) newly arrived at a migratory stopover after crossing the Sahara and Sinai deserts had significantly increased paracellular nutrient absorption (noncarrier mediated uptake occurring across tight junctions between enterocytes) that may provide partial compensation for reduced digestive capacity resulting from changes to intestinal tissues. Indeed, newly arrived birds also had a slightly reduced capacity for absorption of a glucose analogue (3-O-methyl-D-glucose) transported simultaneously by both carrier-mediated and nonmediated mechanisms. Increased paracellular absorption coupled with extended digesta retention time may thus allow migratory blackcaps to maintain high digestive efficiency during initial stages of refuelling while digestive organs are rebuilt.

Original languageEnglish
Pages (from-to)380-385
Number of pages6
JournalJournal of Experimental Biology
Issue number3
StatePublished - 1 Feb 2010


  • Blackcap
  • Carbohydrate absorption
  • Migration
  • Paracellular absorption
  • Refuelling
  • Sylvia atricapilla

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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