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Selection of Deciduous Trees by Free Ranging Voles and Hares in Relation to Plant Chemistry
Joakim Hjältén and Thomas Palo
Vol. 63, No. 3 (Apr., 1992), pp. 477-484
Stable URL: http://www.jstor.org/stable/3544975
Page Count: 8
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In two field experiments the feeding preference of voles (Microtus agrestis and Clethrionomys glareolus) and hares (Lepus timidus), offered winter dormant shoots/branches of three deciduous tree species, were determined and related to nutritional quality and concentration of phenolics. Both the voles and the hares consumed more rowan (Sorbus aucuparia)/aspen (Populus tremula) (vole and hare experiment, respectively) than birch in the patches containing birch (Betula pubescens) together with rowan/aspen and slightly but not significantly more birch than alder (Alnus incana) in the birch/alder patches. Furthermore, the overall consumption in both patch types was highest in rowan/aspen (vole and hare experiment, respectively) and lowest in alder, with birch being intermediate. Food selection was best explained by variations in digestibility, fibre content and phenolic concentration in both the vole and the hare experiments. No selection for plant tissue with a high nitrogen concentration was detected. In fact, consumption was negatively correlated with nitrogen concentration in the vole experiment. Our results indicate that digestibility and the concentration of plant secondary metabolites determine vole and hare utilization of woody browse during winter, whereas nitrogen concentration seemingly is of minor importance. The differences in food preferences between voles and hares are probably caused by either that voles are more tolerant to different types of plant metabolites than hares, or that voles are forced into a broader diet composition due to food stress, or that interspecific differences in chemistry are smaller among juvenile trees than among mature trees.
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