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Calero Lake Estates

President's Column

A League or Less : A Hike on Hawk Ridge

The Trail Companion

December 1997/January 1998

Calero Lake Estates... a tale of trails through serpentine grasslands and the Bay Checkerspot Butterfly

      by Sandy Nichols

The Calero Lake Estates, located near Santa Teresa, is primarily composed of serpentine grasslands. In the summer of '97, a housing developer, after building homes in the area, sought the Trail Center's help in constructing meandering trails through Calero. But before our Crew Leaders could assess work, the project was put on hold pending further studies on the indigenous Bay Checkerspot Butterfly. The butterfly is on the U.S. Fish and Wildlife Service's list of endangered species and it happens that plants that live in serpentine grasslands are the main source of food for the Bay Checkerspots.
      Shortly after announcing our year-long 1998 project, I received a call from the Calero Lake Estates developer informing me that the U.S. Fish and Wildlife Service had taken a strong interest in the property on which we plan to improve an existing trail. Our client met at the site with a Fish and Wildlife representative who expressed some doubts whether we would be allowed to build trail. The area in question consists mostly of sloping, serpentine grassland. Serpentine is a nictamorphic rock that usually parallels fault zones; it fractures, weathers, and erodes to produce a typically thin layer of soil that is "nutrient poor". Specifically, it is lacking enough calcium, nitrogen, and phosphorous to allow vigorous plant growth. This soil limits the type of herbaceous and woody plants that would normally occupy a site within a small geographical area, given a more nutritious soil type. Not only is serpentine soil low in two of the three main nutrients (nitrogen, phosphorous, and potassium), but it is also high in chromium, magnesium, and nickel, which are "heavy" metals. If there is too much magnesium, the plants are unable to take up enough calcium to build new cell walls and membranes. Therefore, the types of plants that can exist in this serpentine grassland environment arc few yet highly adaptive.
      Of the few plants that thrive in serpentine grassland, three in particular are important for a particular butterfly. These are Plantago erecta (plantain), Orthocarpus densiflorus (owl's clover) and Orthocarpus purpurascens (also owl's clover). These herbaceous plants host and sustain Euphydryas editha bayensis, a.k.a. the Bay Checkerspot butterfly. This butterfly, named on the Fish and Wildlife's list of species threatened with extinction, primarily feeds on plantain, while owl's clover is a secondary, but critical, food source.
      Beginning in January, the caterpillar forms its chrysalis to metamorphose into a butterfly. By March, the butterflies come out of their cocoons, mate and lay eggs oi the plantain and then they expire-all within the span of seven days. In April an May, the resulting eggs hatch into half-inch long caterpillars and they voraciousl consume the plantain and owl's clover. When summer comes, the plants dry up and the caterpillars enter a physiologically induced period of dormancy called diapause. The ability to live through diapause depends on when the hatch occurred, the stage of development, caterpillar size at the beginning of diapause and the edible period of the plantain and owl's clover. The diapause ends after the rains faII in autumn.
      The finicky caterpillars have a natural synergistic relationship with local serpentine gophers. As gophers till the soil in the plaintain, they loosen the thin rocky soil which enable the Plantago and Orthocarpus roots to penetrate deeper into the water source. Because of this water access, the plants can survive summer's heat and continue to serve as a food source for caterpillars prior to entering diapause.
      The Bay Checkerspot butterfly is notorious for boom and bust cycles depending on not just gophers, but also slope aspect of the grasslands. A south-facing slope will bake in the summer, while a north-facing slope will be cooler, making it a more hospitable environment for the plantain, and thus the checkerspot. Those caterpillars that survive diapause begin the feast with the return of winter rains to become a chrysalis around January and begin the process again.

      As of today, no one has seen a Checkerspot on the site. The housing developer acquired the property from a previous developer, who obtained it from the "original" developer, who attempted to sneak some improvements on site before all permits were signed. The county "punished" the original developer by adding "trail improvement" to his list of mitigations. That "To Do" list passes with ownership. I'm told that our client hired "the best person at Stanford", Stuart Weiss, a post-doctoral fellow at Stanford in Conservation Biology, whose opinion was that there is no evidence of larvae, insect, or plantain population that would indicate the site is used by, or is particularly suitable for the Checkerspot. The client's permits are in order and have been for some time. But Fish and Wildlife red-tagged the file twenty years ago because of the original developer, so that whenever any new activity is scheduled on the site, a visit from Sacramento is sure to follow.
      The importance of all this is that it has everything to do with us, both as individuals, a society, and as a group of members who are proponents and stewards of parks and open spaces. That claim would extend our obligations to the non-human inhabitants of those spaces as well. We can't argue in favor of acquiring more land for parks and preserves without also "stewarding" what lives inside those borders. We, at the Trail Center, are environmentally conscious; we celebrate and embrace the desire to engage the open spaces for all species.
      The county landscape architect supports our work in Calero. In early November, the Fish and Wildlife Service called the project a "take" which allows the housing developer to either "sell" the land to the Feds or come up with a habitat conservation plan so that the property can be developed.
      The developer informed me that he is in the process of hiring experts to develop the plan, which we hope will be federally approved. This process will probably take a full year. Till then we are busy looking for more trail work.
      (Information for this article came from the following sources: Paul R. Ehrlich, The Butterflies of Jasper Ridge, from The Sciences, 11178; P Ehrlich, Machinery of Nature, 1986; Dr Stuart Weiss, Explaining Butterfly Booms and Busts, from Update, Spring 1997, a publication of the Center for Conservation Biology; California Plant Life, 1974, R. Ornduff- A California Flora and Supplement, 1968, R. Munz)



President's Column

1997 started off with us running between two projects: the second phase of Arguello Park in San Carlos, and the construction of the Bay-Front Trail in Ryder Park in San Mateo. We wrapped up the Ryder Park trail in time to celebrate its opening on National Trails Day in June. We were delighted to give County Supervisor Tom Huening the honor of cutting the ribbon.
      For the summer, we took a short detour from Arguello and did some trail repair and reroute back in Jasper Ridge Biological Preserve. After finishing there, we returned to Arguello, and, by the time you read this, we'll have finished there. The new trails we've constructed in San Carlos should hold up to the intense foot traffic they're sure to receive.
      We've also mapped several trails in preparation for our next peninsula trail map. Trails in El Corte de Madera Creek Preserve, La Honda Creek Preserve, Purisima Creek Redwoods Preserve, as well as the Skyline/Ridge Trail between Wunderlich and Huddart Parks and the trails in the town of Woodside all received visits from our mapping volunteers.
      There were several changes in our office as well. Alice Stem retired in the spring to devote more time to enjoying her grandchildren, and we promoted Sandy Nichols to Executive Director.
      - Scott Heeschen

A League or Less: Hawk Ridge at Dusk (Russian Ridge Open Space Preserve)

Though the long drive to Russian Ridge might make this issue's League or Less too much of an expedition if you have just a couple hours to spare, the ridge-top preserve is well worth the time. I drove to the Caltrans vista point on Skyline Boulevard. On summer evenings, the parking area is often crowded with people taking in the terrific view of the Bay Area, but I had no trouble finding a place. I crossed Skyline and entered Russian Ridge preserve, trading the view of the Bay for a blanket of fog spreading inland from the Pacific. I had a windbreaker to ward off the brisk breeze at parking lot, but once I was below the crest, the breeze let up. By Geoffrey Skinner

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