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Thesis - University Access Only
Master of Science (MS)
Wildlife and Fisheries Science
W. Carter Johnson
Blue jays (Cyanocitta cristata L.) are important predators on and dispersers of nuts of oaks and other Fagaceous trees in eastern North America. Acorns comprise much of the jay diet (Beal 1896), especially during the autumn months when jays may consume or cache a significant portion of an acorn crop. However, jays do not appear to possess physiological adaptations for countering the protein-binding properties of secondary compounds (tannins) found in the acorns of many oak species. I examined responses by blue jays to a mixture of infested and uninfested pin oak (Ouercus palustris Muenchh.) acorns to see if jays selectively consumed nuts containing weevil larvae (Curculio) as a protein supplement to a high-tannin, all-acorn diet (see Johnson et al. 1993. Oecologia 94:159-164). I also tested whether overwinter caching reduced tannin levels in northern red oak (Quercus rubra L.) and bur oak (Ouercus macrocarpa Michx.) acorns, making them more digestible to the jays. Acorns were X-rayed to determine infestation status and then offered to individual jays in an aviary setting. Jays handled and consumed non-infested nuts significantly more often than infested nuts, and proportional use of infested nuts did not increase during continued exposure to a high tannin diet. Acorns in simulated caches did not differ significantly in tannin level from uncached acorns, and jays lost body mass rapidly on both cached and uncached acorn diets. Thus, my results were not consistent with my original hypotheses: jays did not make extensive use of weevil-infested nuts and caching did not appear to improve the quality of an all-acorn diet
Library of Congress Subject Headings
Acorns as food
Includes bibliographical references (pages 92-98)
Number of Pages
South Dakota State University
Copyright © 1994 Mark Dixon. All rights reserved.
Dixon, Mark Douglas, "Acorn Caching and Consumption of Weevil-infested Nuts: Possible Means of Tannin Circumvention for the Blue Jay" (1994). Theses and Dissertations. 332.