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Peak Health

Peak Health

Bird Species
Native Animal Species
Plant Species
Acres Studied
Wildlife Acorn woodpecker | Photo by Nagarajan Kanna


Wildlife are found in every habitat type on the mountain, where they may be grazers, predators, or prey.

Plants Serpentine Barrens | One Tam Image Library


Plant communities, and their arrangement on the landscape, are the foundation of ecosystem health.

Landscapes Landscapes | Photo by Mason Cummings


Most of Mt. Tam’s plant communities are suffering the effects of climate change, invasive species, plant disease, and fire. 

An Ecological Treasure in Our Backyard

The San Francisco Bay Area is part of a nationally and internationally recognized biodiversity hotspot and part of the UNESCO Golden Gate Biosphere Reserve. Located right on San Francisco’s doorstep, Mt. Tam is a vital refuge for many threatened, endangered, and special status species, and is an important link in a much larger network of interconnected open spaces, including the 195,000 acres of protected open space in Marin County that many other plants and wildlife depend upon.

The mountain’s remarkable diversity is thanks to its location near the coast, and to its varied topography, which creates a confounding array of microclimates in a relatively small space. A wide range of soils—including beautiful but harshly metallic green serpentine—create unique niches for different plant communities, and for the animals that depend upon them.  

While Mt. Tam’s plants and animals live in protected open spaces, invasive non-native plants and animals, changing wildfire patterns, plant diseases such as Sudden Oak Death, and climate change still threaten their survival. One Tam partners are working together to monitor, restore, and protect the mountain so that it continues to thrive into the future. 

Measuring the Health of Mt. Tam

Maintaining a healthy, vibrant, and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

This report represents the results of an unprecedented collaboration among Mt. Tam’s land managers, the Golden Gate National Parks Conservancy, and the scientific community to use the most current data and best expert judgment to understand and evaluate the mountain’s health.

How Can I Help?

The Overall Health of Mt. Tam

Mt. Tam’s natural resources are in an overall Fair condition and a trend of No Change. Some of the mountain’s plants and wildlife are thriving, while others are suffering the effects of invasive species, plant disease, changed fire frequencies, and climate change. However, even some of those in decline are at a point where their trajectory can still be improved. The condition and trend of many species or groups like invertebrates and bats remain largely unknown.

Learn more through the links to the WildlifePlants, and Landscapes health indicator assessments above, or download the full report here or download our Health Report at a Glance sheet.


Watch the Story

Data Gaps

The condition of many important indicators of Mt. Tam’s ecological health, including invertebrates, bats, lichens, hardwood forests, riparian areas, and seeps and springs, remains largely unknown. However, now that they have been identified through this process, many of these gaps in our understanding can be improved in the near future, providing important data for the next iteration of this health assessment.

Closing data gaps for broad health indicators like invertebrates and certain plant communities will allow for a much better understanding of the mountain’s overall health. 

Science is an inherently iterative and cumulative process, and this health evaluation will grow and improve along with our understanding of the state of the mountain’s natural resources. 

Health Indicators: Wildlife, Plants & Landscapes

There are many ways to evaluate the health of a mountain, from the condition and trend of an individual species or entire communities, to its biodiversity or climate resilience. Based on a suite of metrics developed for measuring the heath of key ecological indicators, the condition of Mt. Tam’s natural resources is overall cautionary, but fairly stable. Fortunately, some of those indicators that are declining are at a point where their trajectory can still be improved.

Many People, Working Together

  • How Can I Help?
    Give to support the mountain, and the projects and programs helping to maintain and restore this special place.
  • Work Underway
    Stewardship and management has been underway for decades within the One Tam area of focus.
  • Information Gaps
    This assessment process revealed critical data gaps for a number of important health indicators.
  • What We Did
    Determining how to measure the health of the mountain’s resources required a collaborative, iterative, and multi-faceted approach.

Peak Health Indicator Chart

Glossary of Terms

Condition: The current state of the indicator based on the aggregation of its metrics

  • Good: The condition goal is 75–100% met
  • Caution: The condition goal is 26–74% met
  • Significant Concern: The condition goal is 0–25% met
  • Unknown: Not enough information is available to determine condition

Condition Goal: The desired, measurable state for each metric against which monitoring data are compared

Confidence: The amount of certainty with which the condition and trend are assessed

  • High: Measurements are based on recent, reliable, suitably comprehensive monitoring
  • Moderate: Monitoring data lacks some aspect of being recent, reliable, or comprehensive; however, measurements are also based on recent expert or scientist observation
  • Low: Monitoring is not sufficiently recent, reliable, or comprehensive; but either some supporting data exists or measurements are also based on expert or scientific opinion
  • Desired Conditions: The qualitative goal for the overall indicator; the threshold or state it should be in to be considered healthy; often identified as a recovery target for rare/listed species

Indicator: The species, community, or physical process (e.g., stream flow/water quantity) that provides an essential ecological function, or are indicative of essential habitat conditions, and are measured as an indication of health; indicators are akin to human vital signs such as blood pressure and pulse: easily measured and strongly correlated with overall condition, sensitive to stressors, and an early warning of potential problems

Metric: How an aspect of an indicator is assessed or measured

Overall Condition: The combined current state of the indicator based on the totality of its metrics

Stressors: Things that challenge the integrity of ecosystems and the quality of the environment, which may be natural environmental factors, or may result from the activities of humans; some stressors exert a relatively local influence, while others are regional or global in their scope

Trend: The change in condition as determined by comparing current versus previous measures; the trend is independent of current condition (e.g., a resource may be “Declining” but still be in “Good” condition)

  • Improving: The condition is getting better
  • No Change: The condition is unchanging
  • Declining: The condition is deteriorating/getting worse
  • Unknown: Not enough information is available to state a trend