Protecting biodiversity—the amazing variety of life found on Earth—is as essential for us as it is for plants and animals. Biodiversity is what makes nature work. Healthy and diverse ecosystems improve water quality, host important crop pollinators, and keep carbon out of the atmosphere where it contributes to climate change. Biodiversity is what we hear, see, and smell when we are enjoying the outdoors. It is what keeps us happy and alive.

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 critical link in a larger network of open spaces, and a refuge for many species that have lost their habitats to development elsewhere.

The over 41,000 acres of open space on Mt. Tam host ten times the number of native plants per acre as Yosemite, which is almost 20 times as big. Of the over 750 native plants known on Mt. Tam, 6 are found nowhere else in the world, and 49 are listed as threatened, endangered, or rare. The mountain is home to 350 native animal species, 46 of which are officially listed as threatened, endangered, sensitive, or rare.

Mt. Tam’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 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. 

Get Involved

You can help! Learn more through the links below, volunteer for a restoration or monitoring project, or give to support the projects and programs that care for this international ecological treasure in our backyard. 

Biodiversity by the Numbers

The pie chart below represents what we know about Mt. Tam's species diversity at this time, and will be updated on an ongoing basis as we learn more. A single species list for the whole of the mountain was compiled using a combination of existing lists provided by each agency that covered preserves and watersheds within the One Tam area of focus. These data were the result of inventory and monitoring work by agency staff, as well as inventories conducted by third parties on behalf of the agencies, such as Christmas Bird Count, agency BioBlitzes and surveys by the California Native Plant Society, and as such were all verified sightings. Species that had not been reported since 1970 were not included. It is acknowledged that certain taxonomic categories are currently missing, or underrepresented, and that coverage does not always extend to the whole area of focus. This is primarily due to the limitations of only accepting expertly verified sightings from concerted efforts. In particular, very little is known about invertebrates in the One Tam region, and so they are not included at this time. One Tam agency partners are working with scientists to compile any existing information about this important group of creatures, and planning future studies to fill in gaps in our understanding.

Northern Spotted Owl and Redwood Tree Drawing
Species of the Year:

Coast redwoods and Northern Spotted Owls are the 2016 Golden Gate Species of the Year. Get more information about upcoming events here.

Northern Spotted Owl and Redwood Tree Photo
Northern Spotted Owl Monitoring:

The National Park Service and Marin Municipal Water District monitor Northern Spotted Owls. Learn more about what they’ve found.

Image of a Researcher Climbing a Redwood Tree at BioBlitz
Bioblitz Redwood Canopy Exploration:

Researchers recently climbed into the redwood canopy at Muir Woods for the first time. Find out more about what they learned here.

Great Blue Heron Picture


A vital link in a corridor of open spaces, an impressive array of animals lives on or pass through Mt. Tam. Check out the links on this page to find out which creatures call this special place home.

Cynoglossum grande image

Plants and Fungi

From its towering redwoods all the way down to its tiniest forbes, Mt. Tam is a hotspot of plant diversity. Learn more about the mountain’s plant communities here.