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Handling of pinyon pine seed by the Clark's nutcracker.

Johnson, L. Scott and Marzluff, John M. and Balda, Russell P. (1987) Handling of pinyon pine seed by the Clark's nutcracker. The Condor, 89 (1). pp. 117-125. ISSN 1938-5129

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Publisher’s or external URL: http://dx.doi.org/10.2307/1368765

Abstract

Clark's Nutcrackers (Nucifraga columbiana ) are dependent on pine seeds as a food source for both nestlings and adults. Here the authors report on how nine captive individuals open pinyon pine (Pinus edulis ) seeds. Two hulling methods were used: crushing squeezing and cracking the seed coat and separating it from the endosperm while holding the seed in the bill; and pounding, holding a seed between the feet and perch and pounding on it forcefully with the bill until the seed coat cracks. On average, birds crushed 43.7% of their seeds, but three birds pounded over 70% and one crushed over 90%. Seeds that were pounded were significantly wider and had thicker coats than those crushed. Nutcrackers are efficient seed handlers; they use the less costly crushing technique whenever possible, become very proficient at pounding open seeds, and use a very general behavior (bill-clicking) to assess which hulling technique is the most profitable means of opening a seed. The variability in handling behavior documented leads us to suggest that tests of optimal prey choice be based on profitability of prey to, and choice of prey by, individual predators.

Item Type: Article
ID number or DOI: 10.2307/1368765
Keywords: Clark's Nutcracker; hulling methods; food source behavior; bill-clicking; coevolution; handling time; optimal foraging; Nucrifraga columbiana; pine seed; pinyon pine;
Subjects: S Agriculture > SD Forestry
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > School of Forestry
Date Deposited: 22 Dec 2015 21:19
URI: http://openknowledge.nau.edu/id/eprint/516

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