Feeding damage is extensive in the spring before other food sources are available, and bears seem to prefer fast-growing trees of all species. Porcupines eat the inner tree bark, often climbing the tree to reach the thinner, smoother bark. They may partially or completely girdle the tree. Deer and elk browse the tips and branches of young seedlings and saplings, seeming to prefer Douglas-fir. Snowshoe hares and rabbits clip off branches and stems of seedlings.
Mechanical damage occurs as a result of weather events and human activities.
Major storms with severe winds can cause windthrow. Lightning strikes appear as a long, narrow gouge down the side of the trunk. Logging equipment may cause serious injury from bulldozers etc. scraping against trunks and removing portions of bark. Felling trees can cause injury as the falling tree removes branches from residual trees. Bark feeding by bears causes hundreds of millions of dollars' worth of damage.