| Summary: | We evaluated palatability of winter dormant tree twigs to the mountain hare Lepus timidus and the grey-sided vole Clethrionomys rufocanus with captive animals. We tested differences among trees within sites, among sites, and between two tree species (the mountain birch Betula pubescens ssp. czerepanovii and the tea-leaved willow Salix phylicifolia). In one of the sites, we also measured growth rates of autumnal moth Epirrita autumnata larvae on the same trees that were used in preference trials with the hares and voles. The differences in palatability to hares and voles were greatest al the level of tree species; both hares and voles preferred birches over willows, but with the hare there was some overlap in palatability between the tree species. There were also large and significant differences among sites and among trees within sites. Within sites, variation in tree palatability seemed to be larger among willows than among birches. Hares and voles may select willows at least partly on the same basis, but there was no correlation between palatability of the trees to the mammals and the growth rate of the larvae of the autumnal moth on the same trees. Variation in twig palatability to the hares and voles was so large at all levels (among trees within sites, among sites and between tree species) that we suggest it also has implications for food selection of these mammalian herbivores under natural conditions.
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