Collaborative Vital Signs Monitoring in Yellowstone National Park

  • Andrew Ray, Aquatic Ecologist, Greater Yellowstone Network, National Park Service
  • Kristin Legg, Program Manager, Greater Yellowstone Network, National Park Service
  • Hillary Robison, Deputy Chief of Resource Management, Yellowstone National Park, National Park Service
  • Jennifer Carpenter, Chief of Resource Management, Yellowstone National Park, National Park Service, (currently Associate Regional Director of Resource Stewardship and Science – DOI Regions 6, 7, 8; National Park Service)
  • David Thoma, Hydrologist, Northern Colorado Plateau Network and Greater Yellowstone Network, National Park Service

Globally, biodiversity declines and species extinctions are occurring at rates that are unrivaled in human and geological history (IPBES 2019). National parks are not exempt from the combined and interactive effects of climate change, invasive species, habitat loss, novel diseases, and increased recreation that are contributing to these global declines. As a result, parks across the Rocky Mountains (and beyond) are witnessing the loss or declines of iconic species (Newmark 1995, Saunders et al. 2007, Grant et al. 2016), increased presence of drought (Monahan and Fisichelli 2014; Thoma et al. 2019), shifts in the frequency and magnitude of fire (e.g., Balch et al. 2018), and other environmental disturbance. Despite the weighty influence of these environmental stressors, national parks still represent vital biodiversity preserves and natural laboratories that are key to uncovering how nature and humans can coexist through this era of rapid environmental change (Machlis and McNutt 2015).

Central to understanding and promoting the health of national parks is the availability of regularly-collected, high quality, long-term ecological information on key natural resource indicators of park health that the National Park Service (NPS) refers to as “vital signs” (examples include water quality, plant communities, and amphibians; Table 1). With sufficient temporal and spatial granularity, this information provides valuable insight on the ecosystems, biological communities, and species in parks. In Yellowstone National Park, coordinated assessments of ecological health through collaborative, multi-agency monitoring efforts have been part of the culture for several decades and are happening at park and regional spatial scales.

Covers of The State of Yellowstone Vital Signs and Select Park Resources from 2017 and the Yellowstone Science Vital Signs issue about monitoring Yellowstone's Ecosystem health. Both publications were produced by the National Park Service.
Figure 1. Covers of two recently published reports—Yellowstone Center for Resources (2018) and Ray et al. (2019)—that focus on vital signs and the state of park resources in Yellowstone National Park.

Recently, the park published two documents that highlight the importance of vital signs monitoring: The State of Yellowstone Vital Signs and Select Park Resources (Yellowstone Center for Resources 2018) and Yellowstone Science Vital Signs Issue: Monitoring Yellowstone’s Ecosystem Health (Ray et al. 2019) (Figure 1). Both publications emphasize the importance of collaborative, cross-boundary strategies connecting national parks, NPS inventory and monitoring networks, and partnering agencies to leverage scientific connections for maximum conservation impact.

Table 1. Yellowstone National Park's selected vital signs and targeted indicators measured to increase the overall understanding of ecosystem health of the park. Yellowstone assesses the status of these vital signs approximately every three years (Yellowstone Center for Resources 2018). We have highlighted vital signs with statuses of stable to declining or worse conditions (orange), those with improved conditions (blue), and those that are stable or unknown as black. This table is adapted from one presented in the 2017 Yellowstone National Park Vital Signs and State of the Park Resources report (Yellowstone Center for Resources 2018).
Vital Sign Category Vital Signs Key Monitored Indicators Current Status
Ecosystem Driver Climate Daily temperature (Mammoth weather station) Average temperatures are exceeding historical norms
Fire Average acres burned per year (1972–2017; minus 1988) Stable
Average number of fires per year (1972–2017; minus 1988)
Geothermal Systems/Subsurface Geologic Processes Thermal output (chloride discharge through major rivers, heat flux in hydrothermal areas) Stable
Earthquakes per year
Ground deformation in caldera
Geomorphology Yellowstone Lake level (peak) Stable
River discharge, peak rates
River and Stream Hydrology Timing of peak flows Stable to Declining
Magnitude of peak flow
Base flows
Environmental Quality Air Quality Visibility, 5-year average Summers stable to Declining; winter stable
Ozone, 5-year average
Nitrogen in precipitation, 5-year average
Sulfur in precipitation, 5-year average
Particulate matter, annual 98th percentile 24-hour average, West Yellowstone
Carbon monoxide (CO), winter max 1-hour average, West Yellowstone
Nitrogen dioxide (NO2), winter max 1-hour average West Yellowstone
Water Quality Arsenic, dissolved nitrogen, and phosphorus in Yellowstone, Lamar, and Madison rivers (2016) Stable to Declining; Soda Butte Creek Improving
Soda Butte Creek iron, copper, and leads levels
Natural Soundscapes Median sound levels, West Entrance sound station (July 2017 and Winter 2017) Summer Stable to Declining; winter Stable
Resources Amphibians Potential sites suitable for breeding Stable
Catchments occupied by boreal chorus frogs
Major drainages with 4 native species
Alpine Plant Communities Species richness (number of species at GLORIA site) Unknown – not enough sampling conducted to date
Soil temperature; soil nutrients (GLORIA site)
Beavers Beaver colonies - Northeast YNP Stable
Insects Butterflies-species present, butterfly species counted Unknown – not enough sampling conducted to date
Dragonflies-mercury (Hg) levels in larvae
Shrub-steppe Communities Percent cover of native and non-native species, bare ground, and litter in all plots across the landscape Few locations near North Entrance Declining, majority are Stable
Whitebark Pine Greater Yellowstone Ecosystem (GYE) percent blister rust infection Stable to Declining
GYE percent tree mortality, 4-yr trend
GYE percent trees with reproduction potential (i.e., cone producing)
GYE regeneration
The Ecosystem Stressors Aquatic Invasive Species (AIS) Inspected watercraft with AIS Stable
Gastropods (red-rimmed melania [Melanoides tuberculata], New Zealand mud snails [Potamopyrgus antipodarum]) in select waterways
Aquatic invasive vegetation
Invasive Plants Change in density of targeted invasive species after treatment Increasing
Invasive plant species (as ratio of known park vascular plants)
Lake Trout (non-native) in Yellowstone Lake Reduction in lake trout, age 2+ Decreasing
Removal of lake trout
Reduction in lake trout, age 6+
Reduction in lake trout biomass
Land Use Population estimate-GYE Stable
Land use changes (public to private)
Mountain Goats (non-native) Estimate of numbers in and near Yellowstone's boundary Increasing
Visitor and Recreational Use Annual visitation Backcountry recreation- Stable; Visitation-Increasing
Backcountry person use nights
Wildlife Diseases Brucellosis prevalence (adult female bison and elk) Stable to Increasing
Chronic wasting disease (mule deer and elk)
Chytrid fungus, ranavirus prevalence (amphibians)
Distemper and mange prevalence (wolves)
Hantavirus (deer mice)
West Nile virus (birds)
White-nose syndrome (bats)

The State of the Yellowstone Vital Signs and Select Park Resources report provides regular (every few years) updates on the status and trends of a comprehensive list of park resources. In the 2017 report, the trajectories of 21 vital signs (e.g., climate, water quality, and amphibians) were summarized using more than 50 unique indicators (Table 1). In addition to the vital signs’ summary, the status of 20 additional resources of concern including several iconic species (e.g., loons and grizzly bears) as well as cultural and historic sites were presented. The status information for this list of indicator resources helps park managers and scientists more fully understand the park health, serves as a science base for managing natural and cultural resources, and supports ongoing and future research needs.

In the Yellowstone Science Vital Signs Issue released in 2019, several articles highlight the importance of tracking vital signs in Yellowstone and across the Greater Yellowstone Ecosystem and synthesizing parallel and complementary monitoring efforts into a coordinated assessment of ecosystem health. Examples from the Vital Signs Issue include summaries of climate-induced changes in the frequency of fire (Tercek 2019) and historical snow droughts (multi-year periods with unusually low snowpacks; Coulthard et al. 2019). Both patterns are likely to intensify in a warmer future requiring a forward-looking, climate-informed framework for natural resource management (Thompson et al. 2020). Under the current carbon dioxide emissions scenario (i.e., no changes to current emissions levels), forecasts suggest that large fires in Yellowstone National Park will become more common by the end of the 21st century. While forecasts vary in their estimates of the size of future fires, the median future estimate indicates that as much as 50% of the park will burn every decade (Tercek 2019). The increased frequency of large fires is, in part, a result of the shrinking time period when temperatures are cold enough to maintain snow (Tercek and Rodman 2016) and a manifestation of declines in summer precipitation (Holden et al. 2018). These changes in precipitation patterns coupled with increases in temperatures lead to an increase in drought-induced stress on plant communities. In the Vital Signs Issue, we learned that plants that are found in wet meadows and alpine habitats were among the most drought-sensitive vegetation communities in Yellowstone National Park (Thoma et al. 2019). Climate-sensitive wetlands and small glacial lakes in the park, it turns out, support an impressive diversity of plant species with unique adaptations to life in water (Hellquist et al. 2019).

A map of the Greater Yellowstone Ecosystem and Yellowstone National Park in Wyoming, Montana, and Idaho with illustrations of an elk, a grizzly bear, a trumpeter swan, and a whitebark pine.
Figure 2. Understanding the Greater Yellowstone Ecosystem requires collaborative, boundary-spanning work at scales necessary to characterize the movements of the wide-ranging or migratory species of the region.

Symbols are courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (

A key component of vital signs monitoring programs in Yellowstone National Park lies in the careful review, stewardship, and regular sharing of data and observations (Fancy et al. 2009). In Yellowstone and across the Greater Yellowstone Ecosystem (Figure 2), there is a history of collaborative, boundary-spanning work at scales necessary to characterize the wide-ranging or migratory species in the region. Monitoring of elk (Cervus Canadensis nelsoni), grizzly bears (Ursus arctos horribilis), trumpeter swans (Cygnus buccinator), and whitebark pine (Pinus albicaulis) have paved the way in standing up interagency coalitions that are not constrained by the jurisdictional boundaries of land management units. Moreover, these monitoring coalitions have long recognized the importance of regular, unified reporting of the status and trends of Yellowstone’s and the Greater Yellowstone Ecosystem’s vital signs (e.g., The Greater Yellowstone Whitebark Pine Monitoring Program annual reports; GYWPMWG 2020 as an example). The benefits of these coordinated efforts that use consistent methodologies are numerous but include a shared understanding of the status of regional resources and the increased ability to communicate vital signs trends to the diverse stakeholders in the Greater Yellowstone Ecosystem.

A key example of a long-standing vital signs collaboration is the Greater Yellowstone Ecosystem Whitebark Pine Subcommittee. Recognizing the need to conserve the highest elevation tree species in the Greater Yellowstone Ecosystem, the Greater Yellowstone Coordinating Committee, a committee of federal land managers from around the region, stood up the Whitebark Pine Subcommittee two decades ago. Forest ecologists and silviculturalists from the US Forest Service, National Park Service, Bureau of Land Management, and US Fish and Wildlife Service collaborate with partners from participating states (Idaho, Montana, and Wyoming), universities, non-profits, and private land owners (e.g., ski resorts) to implement the Greater Yellowstone Whitebark Pine Strategy (GYCCWBPSC 2011). Actions outlined in the strategy include, but are not limited to, the interagency monitoring led by the Greater Yellowstone Network (GYWBPMWG 2011), research needs, collecting seeds for future restoration, planting seedlings, and protecting select trees from the mountain pine beetle. The Greater Yellowstone Network interagency monitoring program has been instrumental in informing managers on the status and trends of whitebark pine, and monitoring data have been used in the US Fish and Wildlife species status assessment as part of the whitebark pine listing determination under the Endangered Species Act. The Greater Yellowstone Ecosystem Whitebark Pine Subcommittee is held up as a model of a successful, long-standing, cross-jurisdictional partnership that spans three western states, five National Forests, three National Parks, and Bureau of Land Management land in Wyoming, Montana, and Idaho working towards a shared goal of conserving this iconic alpine species. 

The costs of sustaining long-term vital signs monitoring programs with rigorous, statistically valid designs and measurements can be considerable, especially when resource management dollars are scarce. Through our collective experience, we have learned that we cannot let this cloud our understanding of the value of long-term ecological records. In this era of rapid environmental change and high uncertainty, long-term vital signs datasets will provide the NPS with the best opportunity to detect changes in status and establish when long-term trends are reaching critical ecological thresholds (Rodhouse et al. 2016). For example, in Yellowstone National Park, century-old weather station data, long collected by park managers, provide unique opportunities to develop the mechanistic understanding of the connection between key climate drivers (e.g., temperature, ecological deficit [when the water needs of plants exceed the water available to them], and snowpacks) and some of the most iconic park resources (e.g., Yellowstone River and important fisheries). Development of these observed relationships allows managers to anticipate resource change and to project possible trends under plausible future climate scenarios.

As an example of the value of long-term monitoring, consider how the monitoring of carbon dioxide (CO2) concentrations atop Hawaii’s Mauna Loa volcano has proven invaluable in numerous ways, but principally in connecting global temperature changes to rising CO2 levels. When this monitoring was conceived, there was no way to grasp it would someday serve as one of the most valuable scientific geophysical records ever collected. Over 60 years later, the “Keeling Curve” (the measurement of CO2 above Mauna Loa) is a vital sign for Earth health (Keeling 2008;; accessed August 3, 2020). Similarly, imagine how vital signs datasets of today will be used to inform future park management or what NPS and partnering scientists of the future will uncover from the indispensable vital signs records and observations of the past. In the words of Ralph Keeling (2008), “the only way to figure out what is happening to our [parks] today is to measure it, and this means tracking changes decade after decade and [then] poring over the records.”

History has proven that the implementation of the Yellowstone National Park monitoring of targeted vital signs along with the establishment of the NPS-wide Vital Signs Inventory and Monitoring Division to enhance science available to parks were both ambitious and forward-looking. Sustaining these programs hinges on the maintenance of partnerships among decision makers, scientists, and stakeholders that are sustained by trust, mutually defined goals, and shared financial commitments. These components are essential to ensuring that robust and informative long-term vital signs monitoring programs are maintained as core NPS functions. In Yellowstone National Park, vital signs monitoring programs have already characterized the recovery of some of the nation’s most iconic wildlife species (e.g., bald eagles, grizzly bears). Collaborative vital signs monitoring has also helped characterize improvements in Soda Butte Creek in Yellowstone National Park, a blue-ribbon trout stream plagued by decades of mine-related metal contamination (see Henderson et al. 2018). The broader scientific and management communities agree that long-term datasets are already informing land management decisions. These same datasets disproportionately serve as the basis for landmark environmental policies (Hughes et al. 2017).

Vital signs monitoring programs are already uniquely positioned to provide a mountaintop view of complex ecological conditions for decision makers. These programs and findings from the State of the Yellowstone Vital Signs and Select Park Resources report and the Yellowstone Science Vital Signs Issue also serve as underpinnings for a fact-based understanding of ecosystem health, a foundation for establishing sound park policies, and a catalyst for partner and public engagement. Advancing stewardship of Yellowstone National Park resources during this era of rapid environmental change and building from and enriching the investments already committed to vital signs monitoring will require forward-looking and synergistic monitoring and management strategies that are beyond the capacity of the park alone (Leslie 2014; Sauvajot 2016). Advancing stewardship of Yellowstone National Park and the greater NPS will require continued investments in diverse partnerships, thinking at ecologically relevant scales, strengthening the linkages between science and decision making, and, ultimately, committing to bold and deliberate management actions.


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Part of a series of articles titled Intermountain Park Science 2021.

Yellowstone National Park

Last updated: September 10, 2021