California Coast & Ocean

With its white, black, and orange-red dorsal stripes, bright turquoise belly, and orange-red head--not to mention its red tongue and black lips--the San Francisco garter snake (Thamnophis sirtalis tetrataenia) is considered one of the most beautiful snakes in North America, if not the world. How wonderful to have such a creature in our midst!

Yet it has another distinction, one not so wonderful: through human actions over the decades, it has become one of the most endangered snakes on the continent. Declared endangered in 1967 by the federal government--one of the first species to be listed under the new Endangered Species Act--and in 1971 by the State of California, this shy reptile has steadily lost habitat to land development and pollution, and its beauty has led to illegal poaching by collectors. Today, with a population estimated at less than 1,500, the San Francisco garter snake can rarely be seen anywhere but in a zoo.

As if that weren’t enough, its favorite prey, the California red-legged frog (Rana aurora draytonii)--the largest frog west of the Continental Divide, made famous by Mark Twain’s story--is also endangered, because of habitat loss and competition from and predation by nonnative bullfrogs.

Historically, the snake and its froggy food were found in scattered marshes and ponds on both flanks of the Santa Cruz Mountains. (The snake’s name is actually a misnomer, since its range is limited to San Mateo County.) Beginning in the 1940s and into the 1960s, however, when “sag ponds” along Skyline Boulevard, formed by movement of the San Andreas Fault, were drained to make way for people, these animals were squeezed out. Today they are left only in small pockets near San Francisco Airport and around Crystal Springs Reservoir, and locally in coastal wetlands including Pescadero Marsh, Año Nuevo State Reserve, and Mori Point in Pacifica.

Although there’s not much critical habitat left to protect, the good news is that what little remains is getting active help. At Mori Point, the newest unit of Golden Gate National Recreation Area, the nonprofit Golden Gate National Parks Conservancy (GGNPC) has been working hard to give the San Francisco garter snake a leg-up (so to speak). Last year, the park and the conservancy kicked off a habitat restoration and trail improvement project that is intended in large part to help the beautiful reptile.

All for the Snakes
In early March, on a beautiful clear day, I visited Mori Point, guided by Sue Gardner, program director of GGNPC’s Site Stewardship Program. The 110-acre park, on a headland whose fate had been in limbo for decades, finally joined the GGNRA in 2002, after purchase by the Trust for Public Land with help from the Pacifica Land Trust, Coastal Conservancy, and local community members. The purchased parcel is bordered on the north by the San Francisco City-owned Sharp Park Golf Course--once saltwater marsh--and on the east by a small housing development. From this low-lying area the property rises to a prominent blufftop, where Sue and I enjoyed a breathtaking view up the coast to Mt. Tamalpais and, faint in the distance, Point Reyes. Below us, at the bottom of a new set of 198 timber steps, a recreation path--part of the Coastal Trail--stretched atop a seawall toward Pacifica Pier. And downslope to our right was a mid-elevation area of gentle incline--the “heart” of Mori Point and prime San Francisco garter snake habitat.

This heartland is marked now by three freshwater ponds, all constructed by the GGNPC as refuges for the red-legged frog within the past year in the first phase of a two-phase restoration project. Totaling more than 1,200 square feet in surface area, they were designed with the help of a hydrologist to ensure that they will hold water for six months--a requirement of the frog’s breeding cycle. The frogs have already discovered the ponds and have been depositing clusters of gelatinous eggs in them and in nearby Laguna Salada, a natural pond adjacent to the seawall. The chunky little polliwogs will then, hopefully, become foraging fare for the snake. (The snake also eats western tree frog young, but it prefers the larger--and perhaps tastier--red-legged tadpoles.)

In a sense, the seawall created the snake and frog habitat here, because its construction changed what had been saltwater wetlands to freshwater marsh. As housing was built inland, the snakes moved shoreward and came to rely on the marsh landward of the seawall. When the GGNPC built the three ponds in 2007, it expanded this habitat. The lower ponds are fed by the surrounding watershed and tied in with groundwater. The southernmost “perch” pond, finished last October, is fed only by rainfall and runoff and has a clay bottom to prevent percolation of its precious liquid.

The restoration project has been long in the planning. One of the first tasks was to undertake a census of the snake. This was done four years ago, with traplines set by biologists. Only seven individuals were found, said Sue, “but they were male and female, and there was age stratification”--an excellent demographic, promising reproductive potential. Two years ago 13 snakes were counted in a second census. “So all we can say for sure,” Sue noted, “is that the population is increasing. But that’s what we want to see.”

After this crucial groundwork was completed, the restoration project was launched in July 2007. The first phase focused on controlling invasive nonnative plant species, particularly French broom and pampas grass; removing debris left over from prior land uses; erasing informal trails and beginning construction of a streamlined trail system; and building the three ponds.

Before brush clearing, grading, and digging of the ponds could begin, a team of biomonitors made sure the snake wasn’t in danger. “When the weather warms up,” Sue explained, “the snake likes to take refuge in underground burrows. So the biomonitors went in front looking for gopher holes and excavated gently, by hand, each one to make sure there were no snakes in them. When we thought we had everything excavated, we put snake-exclusion fencing around the area so they couldn’t get back in, with a little exit hole in case any were missed--and we left that up until the ponds were finished.”

Not Just Natural History
The day before my visit saw the start of Phase II--brush cutting, in preparation for extensive trail building (including the linkage of the Coastal Trail from north to south)--and Sue was eager to see what had been done. Although the trail work is under way, she explained, “we’re on the cusp of bird nesting season, so we need to cut things low now.” Mori Point, with its confluence of wetland, seashore, coastal scrub, and coastal terrace prairie habitats, is also a birder’s paradise.

As we walked, Sue described the cultural history of the area, which she said is “almost as exciting as the natural history.” The point was first settled in the late 1800s by Stefano Mori, who started out grazing cattle and horses and raising brussels sprouts, cabbage, and artichokes. Facilities to feed and house the ranch hands eventually developed into the income-earning Mori Point Inn, a welcome roadhouse for travelers between San Francisco and Half Moon Bay. In the 1920s, Sue said, local culture “got a little more colorful, when the inn became something of a bordello” and Prohibition sent the then tavernkeeper, Stefano’s son Jack, into a brief career as bootlegger, running Canadian scotch from smugglers’ ships off the point. That all ended in 1923, when Jack was arrested and 24,000 cases of whiskey were confiscated. (The timber steps that connect the bluff and the seawall are called “Bootlegger’s Trail” in honor of this short-lived era.) The roadhouse was revived in 1932 as a restaurant, hotel, and dancehall and remained in use until 1965, when it was condemned and, soon thereafter, burned to the ground.

Other uses of the area have included limestone, rock, and sand quarrying, a cement operation, and motorcycle riding. The former presence of humanity means that “you never know what you’re going to find when you take scrub out,” Sue said. In Phase I, bathtubs, a shopping cart, tires, and vehicle axles were removed. “When we started digging our ponds, we also found diesel fuel”--a nasty surprise that required expensive cleanup. Here and there, small mounds of old asphalt still dot the ground--remnants, probably, of the cement operation.

Near Laguna Salada, on City of San Francisco land, dozens of car tires lie heaped in a large oval--perhaps the remains of an old corral. “The problem with the tires,” said Sue, “besides that they’ll be expensive to get rid of, is that they hold water--which is prime habitat for mosquitoes, of course, but also for frogs.” Although the frogs eat the mosquitoes, they don’t do it fast enough. Recognizing this dilemma, the Mosquito Abatement District helped with the design of the ponds. They will also treat the ponds with Bt (Bacillus thuringiensis, a natural, selective pesticide), Sue said, “which deals specifically with the larvae of the mosquito. All these things are tricky.”

As we made our way along the old road to the south pond, Sue pointed out a hawk rising into the air, a long serpentine creature writhing in its talons. “Put that down!” she yelled. Most likely, it wasn’t a rare San Francisco garter snake but the common coast garter snake, which also inhabits the area. That’s what we hoped, anyway.

Working Together
Sue relies on a small staff, but she couldn’t have accomplished anywhere near as much without a large and diverse group of volunteers, ranging from small schoolchildren to local neighbors. “In areas like this where you have such sensitive species,” said Sue, “historically the emphasis, in terms of protection, has been to fence them off and keep people out. But we really believe that the only way to protect these areas is to engage people in stewardship.”

Fortunately, the local community has leapt enthusiastically to work, participating in clean-ups, salvaging native wetland plants from construction areas, removing nonnative plants and planting new natives in their place, and collecting native plant seeds to support future restoration efforts. They also assisted with the installation of 1,300 feet of protective fencing along sensitive habitat areas.

Eighty-five to 90 percent of volunteer support comes from schoolchildren. Programs are designed by a GGNPC education staff member and an ecology/science staff member, working together “to make sure that what’s done will actually help the area.” Teachers give input as well, “so we can tie in with what’s going on in the classroom.” Outreach staff and interns conduct three to four programs a week with local schools, and Sue has maintained partnerships with Oceana High School and City College of San Francisco that go back 14 years. “At City College,” Sue said, “students taking biology often are taking it in a vacuum because the school is so urban.” Here, with an hour-long lesson on such subjects as island biogeography and how species become endangered, and two hours of field work--removing invasive species, say, or planting natives--they can connect with the land and natural processes.

At Oceana High School, students must do 100 hours of community service. There, Sue helped establish a small native plant nursery, which students maintain; then every Wednesday there’s a work day, when they come out to plant--”so they get to see the whole cycle.” Altogether they’ve grown about 6,000 plants, and a local nursery donated another 10,000, “so we’ve been planting frantically”--as myriad red flags stuck in the ground confirm.

Even small children get hands-on experience at Mori Point. “Believe it or not,” said Sue, in invasive plant eradication efforts “we try to save the ice plant”--but only until a young school group comes along. Then children who can’t do much more get an important job all their own: pulling it out. They also assist in the once- or twice-a-month cleanup of a culvert outflow area--a trash magnet--at one entrance to the park. As Sue observed, “It’s a little disheartening to see a frog--and this is the threatened red-legged frog--sitting on a piece of trash.” Here, the kids use grabbers to pick up trash. “It’s a really tangible thing to do. They almost always get to see the frogs, and then there’s the garbage. It’s kind of instant gratification.”

As Sue and I leave the park by this entrance, we peer into the shallow water near the culvert. Yes, there are a couple of pieces of trash. But there, nestled up against a stick, is the pointed head of a frog. We look a little harder and spot the hindquarters and legs of another one. The sight is gratifying.

Anne Canright’s last article for Coast & Ocean was “Ants!” in the Winter 2007-08 issue.