- Mountain Goats in Yellowstone: Descendants of mountain goats introduced in Montana during the 1940s and 1950s, established a population in the park in the 1990s and have reached a relatively high abundance in the northeastern and northwestern portions via the Absaroka and Gallatin mountain ranges.
- Vegetation: The exact vegetation community present in any area of the park reflects the consequences of the underlying geology, ongoing climate change, substrates and soils, and disturbances created by fire, floods, landslides, blowdowns, insect infestations, and the arrival of nonnative plants.
- Climate Change: Yellowstone's climate is changing. Climate is one of the primary drivers of the processes that make an ecosystem look and function the way it does.
- Bighorn Sheep: Although widely distributed across the Rocky Mountains, bighorn sheep persist chiefly in small, fragmented populations that are vulnerable to sudden declines as a result of disease, habitat loss, and disruption of their migratory routes roads and other human activities.