Effects of exotic species on Yellowstone's grizzly bears

摘要: Humans have affected grizzly bears (Ursus arctos horribilis) by direct mortality, competition for space and resources, introduction of exotic species. Exotic organisms that in the Greater Yellow- stone Area include common dandelion (Taraxacum officinale), nonnative clovers (Trifolium spp.), domesticated livestock, bovine brucellosis (Brucella abortus), lake trout (Salvelinus namaycush), white pine blister rust (Cronartium ribi- cola). Some consume substantial amounts clover. However, these foods provide little digested energy compared to higher-quality bear foods. Domestic livestock are greater energetic value, but use this food often leads conflicts with humans subsequent increases mortality. Lake trout, rust, diminish prey on native cutthroat (Oncorhynchus clarkii) Lake; has potential destroy whitebark (Pinus albicaulis) stands; man- agement response brucellosis, a disease found Yellowstone bison (Bison bison) elk (Cervus elaphus), could reduce populations 2 species will likely cause more harm than good griz- zly bears. Managers few options mitigate or contain impacts exotics Yellowstone's More- over, their negative only begun unfold. may lead loss high- quality foods, including much bison, seeds currently depend upon.