Doug's Mountain Journal
A Chronicle of Natural History on San Bruno Mountain
Doug Allshouse has been writing his seasonal Mountain Journal for many years. It appears in the quarterly newsletters of the Yerba Buena Chapter of the California Native Plant Society (CNPS). We are very pleased to share his seasonal reflections on the natural history of the Mountain. Together with David Nelson, he is writing "The Natural History of San Bruno Mountain", a long-needed and detailed natural history of the Mountain. The book will be published by the California Native Plant Society.
It was a dark and stormy night. Come to think of it, there were many dark and stormy nights in late winter and early spring. Last year’s slightly above-average rainfall was followed by a surprisingly wet year. My rain gauge, located just a half mile from the park’s rain gauge, has recorded 35.85 inches of precipitation, a whopping 11-inch gain over last year! What this created was eroded roads and sloppy trails, over a dozen downed trees (mostly cypress) and a huge sinkhole from a broken pipe carrying Colma Creek’s waters under the Old Guadalupe Trail. Another telltale sign of unfettered river flows was a muddy-brown streak flowing out of the Golden Gate and down the San Mateo County coast; sediment from the Sacramento and San Joaquin river systems washing through the Delta and Bay.
What the extra rain meant were showy displays of annuals like common owl’s clover, goldfields, johnnie tuck owl’s clover and clarkia. And yes, weeds like wild oats, rattlesnake grass, oxalis and Italian thistle are doing well, but then, it seems like they do well every year.
Another species that is doing very well is the creek dogwood. The name is fitting since it does not wander far from creek or stream beds, preferring to keep its feet wet. A beautiful flowering shrub 4-15 feet tall, it is celebrated for its electric-red bark that intensifies during the winter months when it is devoid of leaves. It readily spreads by underground stolons to form thickets and its root system retains soil so well that it is used in restoration to prevent soil erosion.
Look for it along the Bog Trail adjacent to a foot-bridge that crosses a stream and the two bridges that cross Colma Creek. It should be mentioned that Elizabeth McClintock noted that creek dogwood was rare in the landscape in 1967 when she was writing her first flora of the San Bruno Mountains, published in 1968. In the expanded flora of 1990 she stated that dogwood “no longer occurs at localities where it had been observed in the 1960s” due to construction of Guadalupe Canyon Parkway and the expansion of the quarry. Her heart would soar today because dogwood lines Colma Creek wherever willows are absent and they are prevalent in the bog area. Sometimes nice things happen.
Pi Day marked the arrival of an Orange-crowned Warbler heard singing in the willows near the upper Colma Creek bridge with Wilson’s Warbler not far behind. On April 10th a Swainson’s Thrush was heard doing it’s ‘waterdrop’ call, a quick “wit” that kind of sounds like a drop of water hitting a half-full bucket. In early May, the Day Camp produced a Pacific-slope and Olive-sided Flycatcher as well as a pair of California Quails.
The mountain is home to 13 plant species that are considered rare, threatened, or endangered on a CNPS state or local level, some of them are reasonably common here. The fear of extirpation of any of these plants is always palpable. Last year we (David, Mark and me) found San Francisco campion (Silene verecunda) which hadn’t been seen for many years. On the last Saturday in February we were exploring an area in the Great Meadow and I spied some shooting stars. As David was photographing them I noticed a few small white flowers on small, short rosettes and whipped out my hand lens. The plant was definitely a member of the borage family. I hastily summoned Mark to have a look and told David to stop standing on them and have a look. We were flummoxed but took photos and thanks to Cal Flora narrowed it down to two species in the genus Plagiobothrys. It took about 5 weeks and thanks to Ron Kelly, who did the borage family for Jepson, our suspicion was confirmed. We had found the presumed-extirpated species Plagiobothrys chorisianus, Artist’s or Choris’ popcorn flower, named for the artist on the Kotzebue expedition, Ludvig Choris. No one had seen this plant in 33 years. We obtained County Parks’ permission to do some light restoration work in the area by removing a Monterey pine, thistles, wild oats and filaree.
We also found an adjacent population of Cleveland’s cryptantha, also a borage family member, that is much hairier with flowers that are a microscopic 0.5 mm wide. Ironically both genera share ‘popcorn flower’ as a common name. These two species were on the banks of a creek and we became acutely aware that during the huge storms of January and February that these plants were under 3 feet of raging water. They not only survived, but thrived. Tough little guys.
The final great story of the year, so far, was the reintroduction to SBM of the extirpated Bay Checkerspot butterfly, a US Fish & Wildlife threatened species, by Dr. Stu Weiss of Creekside Science. 3,630 caterpillars were transported from Coyote Ridge in southern San Jose; the same location that supplied checkerspot larvae to Edgewood Park in Redwood City.
Stu also reintroduced the Mission Blue butterfly from SBM to Twin Peaks as well as the Chalcedon Checkerspot from SBM to the Presidio. What makes the story even more intriguing is the butterfly’s switch in host plants. Like our 3 other endangered butterflies—Mission Blue, San Bruno Elfin, Callippe Silverspot—the Bay Checkerspot is monophagous, which means its larvae feed on one type of food plant. In this case, the checkerspot originally fed on native dwarf plantain, Plantago erecta and occasionally on purple owl’s clover. A species of checkerspot in Washington had switched over to the non-native English plantain, Plantago lanceolata. After studies that the abundance of both plantains on the mountain were deemed sufficient, the larvae were put on the non-native English plantain. Adults were seen flying and have produced a new generation of larvae. We’ll know how successful this reintroduction has been next year but, for now, it’s good to know that an old friend has been reacquainted with the mountain. It’s been absent since 1985. Welcome back!
See you on the mountain...