Effects of Caching on Acorn Tannin Levels and Blue Jay Dietary Performance

Publication Type:Journal Article
Year of Publication:1997
Authors:Dixon, MD, W. Johnson, C, Adkisson, CS
Journal:The Condor
Date Published:1997
ISBN Number:00105422
Keywords:Corvidae, Cyanocitta, Cyanocitta cristata, Garrulus, Garrulus glandarius
Abstract:Blue Jays (Cyanocitta cristata) are important consumers and dispersers of the nuts of oaks and other fagaceous trees in eastern North America. Acorns comprise much of the jay diet, especially during the autumn when jays may spend considerable time harvesting and consuming or caching acorns. However, jays do not appear to possess physiological adaptations for countering the protein-binding properties of secondary compounds (tannins) found in acorns. We tested whether simulated overwinter caching would reduce tannin levels in northern red oak (Quercus rubra) and bur oak (Q. macrocarpa) acorns, enabling jays to subsist on a cached acorn diet by circumventing the negative effects of high tannin levels in the acorns. After overwinter storage, acorns in simulated caches did not differ significantly in tannin level from uncached acorns, and jays lost weight rapidly on both cached and uncached acorn diets. Thus, simulated caching did not appear to significantly reduce tannin protein-binding activity of acorns, nor enable jays to better subsist on an all-acorn diet.
Short Title:The Condor
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