Trophic cascades from wolves to grizzly bears in Yellowstone

摘要: Summary 1. We explored multiple linkages among grey wolves (Canis lupus), elk (Cervus elaphus), berry-producing shrubs and grizzly bears (Ursus arctos) in Yellowstone National Park. 2. hypothesized competition between whereby, the absence of wolves, increases numbers would increase browsing on decrease fruit availability to bears. After were reintroduced with a reduced population, we there be an establishment shrubs, such as serviceberry (Amelanchier alnifolia), which is major plant. also that percentage bear diet greater after than before wolf reintroduction. 3. compared frequency scats densities prior reintroduction during time increasing (1968–1987). For period reintroduction, calculated scat by month based collected 2007–2009 (n = 778 scats) these results data Additionally, developed age structure for showing origination year stems northern range study area. 4. found over 19-year period, (6231 was inversely correlated (P <0 001) population size. The average higher July (03% vs. 59%) August (78% 146%) before. All measured accessible ungulates originated since while protected growing nearby ungulate exclosure both Moreover, recent years, outside decreased their heights increased. 5. Overall, are consistent trophic cascade involving increased predation other large carnivores elk, redistributed herbivory production plant-based foods may aid threatened