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Natural Areas

Twin Peaks

  • Location: Twin Peaks Boulevard
  • Size: Park: 34.1 acres/Natural Area: 31.1 acres
  • Park Type: Grassland/Coastal Scrub

At 922 feet in elevation, Twin Peaks is second only to Mount Davidson in height, offers spectacular views of the Bay Area, and is a world-famous tourist attraction. Originally called "Los Pechos de la Choca" (Breasts of the Maiden) by early Spanish settlers, these two peaks provide postcard views and a treasure trove of animal and plant diversity. Most visitors to Twin Peaks drive (or take a tourist bus) to the north peak parking lot to enjoy 180-degree views of the Bay Area. Unfortunately, many of them miss an opportunity to experience the coastal scrub and grassland communities on this 64-acre park. Similar to the Marin Headlands, Twin Peaks gives us an idea of how San Francisco's hills and peaks looked before grazing and then development changed them forever.

Natural History

Twin Peaks is a prominent dividing point for the summer coastal fog. West-facing slopes receive substantial fog and strong winds while the east-facing slopes receive more sun and warmth. The vegetation is primarily a mix of grassland and coastal scrub. Expect strong winds as you hike among plants such as coyote brush, lizard tail, and pearly everlasting. These plants provide habitat for brush- nesting birds like the white-crowned sparrow and animals such as brush rabbits.

The Mission Blue Butterfly

The mission blue butterfly is a federally listed endangered species that still survives in a few areas of San Francisco, Marin, and San Mateo counties. Silver lupine is one of three native lupine species that provide habitat during different stages of this fascinating butterfly's life. The female butterfly lays eggs on the lupine and feeds on its nectar. When the eggs hatch, the newly emerged caterpillar feeds on the inner parts of the lupine leaves. Once the caterpillar has obtained enough food energy for the winter, it crawls down to the base of the plant and goes dormant. The following spring the caterpillar will emerge to feed again and return to the ground to pupate, emerging from its cocoon as a butterfly. Like many butterfly species, mission blue's larvae have a mutualistic relationship with ants. Caretaker ants stroke the larvae with their antennae, which causes them to secrete a sugary fluid, called honeydew, that the ants crave. In return, the ants protect the larvae from predators and parasites.

Park Images

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Park Features: