Wolf

At the end of 2008, at least 124 wolves in 12 packs and various groups occupied Yellowstone National Park. This is one more pack than in 2007, but several long-term, stable packs were lost and smaller, newly formed packs replaced them. This represents a 27% decline compared to the 2007 population and was similar to the 30% decline in 2005. Only six of these packs were breeding pairs, the smallest count since 2000 (when wolves first reached the minimum requirement for delisting of 30 breeding pairs in Idaho, Montana, and Wyoming). High mortality of both pups and adults caused the low breeding pair count, despite there being 12 packs. Disease and intraspecific mortality are the two primary factors that caused the wolf population decline.