| Dilute bird nectars: viscosity constrains food intake by licking in a sunbird. | |
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MedLine Citation:
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PMID: 20686174 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Floral nectars of bird-pollinated plants are relatively dilute. One hypothesis proposed to explain this concerns the difficulty for birds of drinking nectar of high viscosity. We examined the effects of viscosity, separately from those of sugar concentration, on feeding by captive whitebellied sunbirds (Cinnyris talatala). Viscosities of artificial nectar (sucrose solutions ranging in concentration from 0.25 to 1.5 mol/l) were altered with Tylose, an inert polysaccharide. Food consumption was measured over 3 h, and lick frequency and duration were recorded using photodetection devices on feeding apertures too small for the bill but large enough for the extended tongue. Volumetric intake rates (ml/s) were inversely proportional to nectar viscosity, and were similar over the range of sucrose concentrations when viscosity was held constant. Sucrose intake rates (mg/s) remained the same on pure sucrose solutions, but they decreased with increasing viscosity at a constant sucrose concentration. Lick frequencies and tongue loads were reduced at high viscosities, and lick duration increased, which confirms that sunbirds take longer to ingest viscous solutions. Licking behavior was remarkably similar in birds feeding on different sucrose concentrations if viscosity was held constant. Nectar ingestion rate is determined by viscosity; however, total food intake is mainly modulated by sugar concentration. Similar effects of food viscosity have been observed in insects that suck nectar. |
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Authors:
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Angela Köhler; Carolina D C Leseigneur; Luke Verburgt; Susan W Nicolson |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-08-04 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 299 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2010 Oct |
Date Detail:
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Created Date: 2010-10-01 Completed Date: 2010-10-19 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R1068-74 Citation Subset: IM |
Affiliation:
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Dept. of Zoology and Entomology, Univ. of Pretoria, South Africa. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Diet Eating / physiology* Methylcellulose / analogs & derivatives, chemistry Microscopy, Electron, Scanning Passeriformes / physiology* Solutions Sucrose / chemistry Tongue / anatomy & histology, physiology Viscosity |
| Chemical | |
Reg. No./Substance:
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0/Solutions; 57-50-1/Sucrose; 9004-59-5/methylethylcellulose; 9004-67-5/Methylcellulose |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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