Central place foraging by beavers (Castor canadensis): A test of foraging predictions and the impact of selective feeding on the growth form of cottonwoods (Populus fremontii)
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Authors: M. A. McGinley, and T. G. Whitham
Date: 1985
Journal: Oecologia
Volume: 66
Number: 4
Pages: 558-562
Summary of Methods: Beaver foraging behavior and the impacts it has on cottonwoods was studied in a well developed, evenly-aged stand of riparian trees and shrubs along the San Juan River near Chinle Wash in southern Utah using a central place foraging model. Cottonwood trees at nine pre-determined distances (3.5 m to 73 m) from the river were examined to determine the relationship between the distance from the river and size of branches chosen. The number of cut and uncut branches was recorded for 10 plants at each distance.
Article Summary / Main Points: Seventy-one percent of the branches were cut by beavers at a distance of only 3.5 m from the rivers edge while only 20 percent of the branches were cut at a distance of 73 m. The central place foraging theory predicted large branches would be favored at all distances and the mean size of cut branches averaged 97.9 percent greater than uncut branches. Trees near the river did not differ in age from those farther from the river; the evenness of tree age differences and growth form were most likely due to beaver harvesting and/or micro-habitat differences with distance. Plant growth form and plant reproductive patterns were affected by selective harvesting of branches. The more branches removed by the beaver the shrubbier cottonwood growth form becomes. Foraging of beavers did not kill the cottonwoods but results in the production of a dense hedge.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 35 Colorado Plateau
Agrovoc Control Words: Beavers Grazing Cottonwoods
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: beavers, castor canadensis, forage, selective feeding, cottonwoods, populus fremontii, central place foraging theory
Annotation: The results can be applied to cottonwood dominated riparian areas inhabited by beavers. The advantage of applying foraging models is that they can be used for a large area and take less time to apply than field studies. The major limitation of foraging models is that results may not accurately reflect site-specific outcomes and before the results are used to make management decisions the model results should be confirmed with field studies.
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