What make evergreen needles so distasteful to some herbivores in taiga?

Evergreen needles, such as those from spruce and pine trees, are often distasteful to some herbivores in the taiga due to their high resin content and tough, acidic fibers. These characteristics make them less palatable and harder to digest compared to deciduous leaves. Additionally, the presence of secondary metabolites, which can be toxic or unappealing, further deters herbivores from consuming these needles. As a result, many animals in the taiga prefer more tender and nutrient-rich foliage when available.