Invertebrates—or animals without a spine—include a wide range of creatures from honeybees to banana slugs. The Mt. Tam region is home to several overwintering monarch butterfly roosts, and its Sargent cypress forests host the rare indigenous Muir hairstreak butterfly. Although invertebrates may make up the majority of the biodiversity in a given ecosystem, because of their small sizes and sometimes cryptic lifestyles, less is known about this important and group of animals than any other on Mt.
Sharp-eyed visitors to Mt. Tam are frequently treated to the sight of a snake sunning itself on a rocky outcrop, or the sound of a lizard scurrying under the leaves beside the trail. Western pond turtles, a California Species of Special Concern, also live on Mt. Tam, though their numbers have declined dramatically throughout the state in recent decades. The species has disappeared from Muir Beach, but on-going monitoring of the small remaining population farther up the mountain is being used to inform protection and restoration efforts.
Long-lived, thin-skinned, and totally dependent on natural water sources, Mt. Tam’s amphibians are good indicators of the health of its streams and wetlands. One Tam partner agencies have been monitoring threatened California red-legged frogs and foothill yellow-legged frogs (a state Species of Special Concern) for quite some time. Habitat restoration at Muir Beach has led to a rebound of red-legged frogs there, but numbers of yellow-legged frogs farther up the mountain are still perilously low.
Mt. Tam’s streams support 5 species of fish. Federally endangered coho salmon and threatened steelhead trout are of particular interest to One Tam partner agencies. These large, charismatic fish play crucial roles in both stream and ocean ecosystems. Currently coho are in steep decline and are at risk of being lost from the Redwood Creek watershed, though Lagunitas Creek boasts a more stable population. Steelhead trout appear to be doing relatively well, but managers are still keeping a close eye on their numbers through annual monitoring programs.
Thanks to its diversity of habitats and microclimates, the songs of birds may be heard in every corner of Mt. Tam. Located along the Pacific Flyway—a major bird migration corridor that stretches from Alaska to South America—the the mountain is an important resting and feeding spot for migratory species as well as its year-round residents. Of the 167 bird species that live on, or pass through the area, 28 are threatened, endangered, or of special concern. Some notable residents Include threatened and endangered species such as Northern Spotted Owls and Ridgway’s Rails.
Mt. Tam’s wide array of microclimates and relatively high air quality support a remarkable diversity of lichens. The rare Methuselah’s beard (Usnea longissimia) is one of the 284 known lichen species on Mt. Tam, and there are still many more areas left to be surveyed. The California state lichen, lace lichen (Ramalina menziesii), also grows in oak woodlands and Douglas-fir forests around the mountain.
From bats to badgers, chipmunks to coyotes, otters to opossums, and skunks to squirrels, Mt. Tam is home to an abundance of mammals. The Wildlife Picture Index Project is using motion-activated cameras to learn about what kinds of mammals are found on the mountain, and how they use its different habitats. What we learn will help us make better decisions about how to protect the places on
Invasive, non-native plant species possess particular qualities like fast growth, high seed production, and rapid maturation that—when combined with a lack of the natural predators and diseases that controlled them in their native environment—allow them to rapidly grow and spread. Mt. Tam is an important natural refuge in a largely urbanized area, but being near human development also means that it faces a continuous barrage of invasive, non-native plant species. In many areas across Mt.
In nature, all things are connected. A plant, even one that is small or unglamorous, may provide vital food or shelter to other creatures. Its roots may stabilize the shifting earth below. If a plant species becomes very rare, it may no longer be able to fill these important roles, and its risk of extinction can become quite high. A remarkable 49 rare plants have been identified on Mt. Tam.
Mt. Tam’s seasonal wetlands, marshes, seeps, springs, ponds, and streams provide precious water in an otherwise relatively arid environment. This network of riparian corridors and other wet areas support several rare plants, and offer water, food, and refuge to creatures across the whole mountain. Bothin Marsh is home to threatened and endangered species like the California clapper rail and salt marsh harvest mouse. Redwood and Lagunitas Creeks support endangered coho salmon and threatened steelhead trout and California red-legged frogs.