Yellowstone National Park is a fully functioning ecosystem, one constantly in motion as wildlife populations ebb and flow, climate slowly changes, and geologic processes continue. Details of some of those changes are reflected in the park's 2013 Natural Resource Vital Signs report.
For instance, while the park's grizzly bear population seems to have stabilied at its carrying capacity, Yellowstone's elk numbers have declined significantly in recent years, while wolf numbers have dropped as well.
The Vital Signs report is compiled from data collected by park scientists and their cooperators from more than two dozen indicators to study the influences, both inside and outside of the park, that affect Yellowstone’s overall ecological status and the condition of cultural resources. Ecological indicators include ecosystem processes such as wildland fire, as well as the status of native species and stressors such as wildlife disease and non-native species.
All three reports, published by the park’s Yellowstone Center for Resources, help inform resource management decisions and support ongoing and future research needs.
According to Yellowstone officials, highlights from this year’s Vital Signs report include:
* Climate: Precipitation data suggest that the park is still in a long-term drought. Recent data support a continued trend of warming with average low temperatures increasing by 4.6 degrees since 1989.
* Bears: Grizzly bear numbers appear to be stable in the GYE this year; supporting recent discussion that bears have reached carrying capacity in the ecosystem.
* Wolves and elk: Elk surveyed along the northern range of Yellowstone continued to decline as a result of multiple factors, but show signs of stabilizing at a new low. The number of wolves that spend most of their time in Yellowstone declined slightly.
* Bison: The conservation of Yellowstone bison continues to be successful with population numbers over 4,000 bison.
* Historic structure conditions and archeological sites: Historic structure assessments of the 880 buildings, roads, bridges, and grave markers have been completed for 80 percent of the sites. About 77 percent of historic structures and 65 percent of known archeological sites are in “good” condition.
* Native fish: There are signs that the number of Yellowstone cutthroat trout in Yellowstone Lake is increasing. Efforts to reduce the population of non-native lake trout have resulted in the removal of over 1 million lake trout from Yellowstone Lake. Arctic grayling and westslope cutthroat trout restoration efforts began in 2013 as part of the native fish preservation effort.
The 2013 Vital Signs report can be found online at this site.
The wolf and bird program reports are available here: