Pacific chorus frogs make urban comeback


  • A Pacific chorus frog, at home in an industrial drainage ditch.

    Rob Schell
 

As dusk fell one spring evening in 2003, a small group of volunteers crawled along a creek bank, searching among tall grasses, under piles of decaying garbage and in stagnant puddles for gelatinous clutches of eggs.

The Port of San Francisco was about to build a new bridge over Islais Creek Channel on the city's southern waterfront, and time had nearly run out for its Pacific chorus frog colony. Urban development and predation by invasive birds and fish had wiped out most of the city's frogs. Before backhoes carved away one of their last bits of habitat, volunteers spirited as many frogs as they could to an unassuming marshy pit tucked between warehouses, freeways and parking lots.

Nearly eight years later, this ad hoc sanctuary is teeming with frogs. The exact location is a carefully kept secret, to avoid visits from wildlife collectors and the curious, who might cause inadvertent harm or introduce disease. Only a handful of herpetologists, who prefer to remain anonymous, know just where to find the colony. They visit it regularly to monitor water quality, measure egg production and tend to native plants. For the most part, they work under the radar: without permits to collect and transplant frogs, and outside the auspices of any formal program or organization.

Why so much trouble for a few slimy amphibians? Although Pacific chorus frogs inhabit marshy puddles all along the West Coast, Islais Creek Channel is thought to have been the last refuge of one of San Francisco's oldest gene lines, so its frogs are particularly well suited to the city's peculiar microclimates, foliage, predators and prey. That means they can act as bio-indicators for local ecological restoration projects, connecting the aquatic and terrestrial food webs to reveal the health of an ecosystem with their presence -- or lack thereof.

For a few years, the new habitat was a lonely island in an industrial wasteland. As tractor-trailers rumbled past, a thin trickle of water from a nearby hillside was the frogs' primary lifeline.

But now, thanks to guerrilla preservation efforts and amphibian vigor, the frogs are on the brink of an unexpected comeback. Their camouflage and foraging abilities, as well as homing instincts that scientists have yet to fully understand, make them a particularly resilient species. And as the city has converted former industrial areas into green space, chorus frogs have been surprisingly adept at establishing pathways -- sometimes through gutters and sewers -- to new habitat.

Nobody knows, or is willing to acknowledge, whether they've had human help along the way. Regardless, the frogs' territories are expanding. So far, they've found their way into parks, marshes, even backyards. Finding them is easy: Come March, cartoon-like ribbits resonate on street corners in the Mission district alongside the sizzle of food carts and whine of electric buses.

Frogs are calling in the Presidio, too. The former military base at the foot of Golden Gate Bridge is now a national park, and it is undergoing a comprehensive ecological restoration. Although a recent wildlife survey failed to find proof that chorus frogs had moved in, Presidio biologist Mark Frey has heard them singing, and thinks it's only a matter of time.

"I think the long-term opportunity for the frogs to occur (in the Presidio) is because of the restoration, at least in part,"  Frey says.

Though much of the frogs' resurgence seems to be an accidental byproduct of open-space restoration, it's possible their return could have been even more widespread had it been part of a more robust, officially sanctioned effort.

"Amphibians are disappearing all over the planet, but they were able to survive here," says David Erickson, a neighborhood organizer who worked for years to restore the habitat around Islais Creek. "This is a miracle."

High Country News Classifieds
  • CROWN OF THE CONTINENT COMMUNITY CONSERVATION SPECIALIST
    THE WILDERNESS SOCIETY is seeking a Community Conservation Specialist, for the Crown of the Continent DEPARTMENT: Conservation CLASSIFICATION: Grade 6 Specialist/Representative (Low of $54K) REPORTS...
  • ASSISTANT FARM DIRECTOR
    About The Organization Building community through fresh vegetables is at the heart of the Sisters-based non-profit, Seed to Table Oregon. Based on a four-acre diversified...
  • CARPENTER WANTED
    CARPENTER WANTED. Come to Ketchikan and check out the Rainforest on the coast, Hike the shorelines, hug the big trees, watch deer in the muskeg...
  • DYNAMIC EXECUTIVE DIRECTOR
    VARD is seeking an Executive Director to lead a small legal & planning staff dedicated to the health and sustainability of Teton Valley Idaho and...
  • WATER PROJECT MANAGER, UPPER SAN PEDRO (ARIZONA)
    Based in Tucson or Sierra Vista, AZ., the Upper San Pedro Project Manager develops, manages, and advances freshwater conservation programs, plans, and methods focusing on...
  • CAMPAIGNS DIRECTOR
    Southeast Alaska Conservation is hiring. Visit https://www.seacc.org/about/hiring for info. 907-586-6942 [email protected]
  • FINANCE & GRANTS MANAGER
    The Blackfoot Challenge, located in Ovando, MT, seeks a self-motivated, detail-oriented individual to conduct bookkeeping, financial analysis and reporting, and grant oversight and management. Competitive...
  • WADE LAKE CABINS, CAMERON MT
    A once in a lifetime opportunity to live and run a business on the shore of one of the most beautiful lakes in SW Montana....
  • CONTRIBUTING EDITOR, BOOKS, CULTURE AND COMMENTARY (PART-TIME, CONTRACT)
    High Country News is seeking a Contributing Editor for Books, Culture and Commentary to assign and edit inquisitive, inspiring, and thought-provoking content for HCN in...
  • STATEWIDE COMMUNITY ORGANIZER
    ABOUT US Better Wyoming is a nonprofit, nonpartisan advocacy organization that educates, organizes, and mobilizes Wyoming residents on behalf of statewide change. Learn more at...
  • EXECUTIVE DIRECTOR
    TwispWorks is a 501(c)3 that promotes economic and cultural vitality in the mountainous Methow Valley, the eastern gateway to North Cascades National Park in Washington...
  • CLEAN ENERGY ADVOCATE OR DIRECTOR
    Location: Helena, Montana Type: Permanent, full time after 1-year probationary period. Reports to: Director of Policy and Legislative Affairs. Travel: Some overnight travel, both in-state...
  • PROFESSIONAL GIS SERVICES
    Custom Geospatial Solutions is available for all of your GIS needs. Affordable, flexible and accurate data visualization and analysis for any sized project.
  • DEVELOPMENT DIRECTOR
    Restore Hetch Hetchy, a 501 (c)(3) nonprofit organization, seeks experienced development professional to identify and engage individuals and institutions who are inspired to help underwrite...
  • PUBLIC LANDS COUNSEL
    The successful candidate will be the organization's lead counsel on public lands issues, including reviewing federal administrative actions and proposed policy and helping to shape...
  • HUMAN RESOURCES DIRECTOR
    Solar Energy International (SEI) is a 501(c)3 non-profit education organization with a mission to provide industry-leading technical training and expertise in renewable energy to empower...
  • TRAINING MANAGER
    This is a full-time position based out of our Paonia office. This position is responsible for organizing all of Solar Energy International's renewable energy trainings....
  • GUIDE TO WESTERN NATIONAL MONUMENTS
    NEW BOOK showcases 70 national monuments across the western United States. Use "Guide10" for 10% off at cmcpress.org
  • RARE CHIRICAHUA RIPARIAN LAND FOR SALE
    40 acres: 110 miles from Tucson: native trees, grasses: birder's heaven::dark sky/ borders state lease & National forest/5100 ft/13-16 per annum rain
  • ENVIRONMENTAL GEOPHYSICS
    "More Data, Less Digging" Find groundwater and reduce excavation costs!