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 reflections on the natural history of the Mountain. Together with David Nelson, he is writing San Bruno Mountain: A Guide to the Flora and Fauna. The book will be published by Heyday Books in 2022.
“Did someone forget to pay the water bill?” I imagine this is a conversation that some of our annual plants are having in April. The last recorded precipitation was March 19 and to date we have recorded a measly 10.36 inches. That is the lowest total by April 15 of any of the seasons below 20 inches, which is the low side of average rainfall for San Bruno Mountain, 20-24 inches. Even if we have the best April, May and June since I have kept records, we would end the season with 16.74 inches of precipitation. As it stands right now we will not exceed the worst year (2013-14) of 13.85 inches. Those 10.36 inches include 1.40 inches of fog drip on 64 days. We have had only 9.96 inches of actual rain.
The poppy and lupine show
The perennial wildflowers have barely noticed the paltry rainfall. The poppy and lupine show on Juncus Ridge was out in full force in late March. If there is any positive situation of this cold and dry year it would be the fact that the European annual grasses are half as tall as usual. One April morning I noticed many splashes of yellow in the main picnic area. They turned out to be suncups (Taraxia ovata) which have always been there, but now the stunted grasses allowed them to shine.
Most morning walks are quiet and uneventful, but eventually something breaks the silence. On April 4th I was walking the upper Bog Trail under some cypress trees. Suddenly a sound and feeling reminiscent of raindrops broke the silence. I turned around to see two squirrels barreling headfirst down a trunk through the clinging English ivy. Across the trail they scampered and through the ferns and willows in the direction of Colma Creek. Suddenly I heard another sound up in the cypress and I spotted two more squirrels who seemed confused about what to do. Within a millisecond they bolted across a large branch, leaped a few times down to lower branches, and scurried down a small willow to the ground, heading in the same direction as the first two. Wow, I thought, they must be late for a Zoom meeting or else awfully thirsty. Frightened or motivated squirrels are, hands down, the most athletic creatures ever to grace the Earth. Why they were in such a hurry remains a mystery. Ten minutes later I heard my first Wilson’s Warbler of the spring. If you throw in the California Quail I heard 30 minutes prior to the squirrel episode you can safely say, “Good things happen in threes.”
Monomorium ergatogyna on Choris’ popcorn flowers.
COVID restrictions for the Park have put quite a damper on my springtime activities so I also squeezed in two checkups on rare plants. The first was a stop on Radio Road for a descent down a steep meadow through dwarf brodiaea, common owl’s clover and a small sprinkling of goldfields. At the bottom is the only known population of Choris’ popcorn flower, a definite water-lover. With the dearth of rainfall this season the plants were blooming in what would be the creek bed in a more normal year instead of blooming on the bank of the creek. I surmised that the April Brook did not run seasonally this year, but the popcorn flower is still there, doing as well as could be expected, and that’s what is important. And yes, I found a few Small Black Ants (Monomorium ergatogyna) on some flowers.
I applied for a Site Activity Review from County Parks for a second year of removing two invasive species of clover on the Ridge Trail. This infestation is near the reintroduction site of the threatened Bay Checkerspot butterfly. Last year with help from Stu Weiss we removed 6 landscaping bags full of narrow-leaved clover (Trifolium angustifolium) and rose clover (T. hirtum). In mid-April I made my way out on the Ridge Trail to do some reconnaissance of the clovers. It was a horribly windy and slightly foggy afternoon when I threw my Explorer into high 4X4 drive and headed east.
The first thing that surprised me was the thousands of lace parsnip (Lomatium dasycarpum) plants that lined the shoulders of both sides of the road for almost a mile. I have never seen such a display of this once-crucial larval plant for the Anise Swallowtail butterfly in all my years on San Bruno Mountain. I say “once-crucial” because this butterfly that exclusively used the native lomatiums and cow parsnip will frequently use the rather abundant non-native fennel. Likewise, the threatened Bay Checkerspot now uses the non-native English plantain (Plantago lanceolata) in lieu of the native plantain (P. erecta) and common owl’s clover (Castilleja densiflora). The reason for using these non-natives is due to their availability and the evolution of these species in their struggle to survive. One possible reason for the sudden abundance of the lace parsnip is the County brushed back the scrub 6-8 feet on the shoulders of the major fire roads. They did not disturb the native butterfly habitat of the San Bruno Elfin on Radio Road or the Mission Blue habitat on Battery Road 59 (West Peak); ditto for the MB, BC and Callippe Silverspot habitat on the Ridge Trail. The clover was not to be found, which is encouraging, but with our cold dry winter my thought was that the clover is behind schedule. I plan another outing in a few weeks.
Anise swallowtail larva
After locking the gate on the summit, I checked on the San Francisco campion growing on the rock wall by the upper parking lot. I found only two plants that were considering possibly flowering and the rest were basically basal leaves with no stalks. There are a few more populations in the area to check out, but the blistering wind and returning fog diminished any thoughts other than getting back in my SUV and heading home.
Despite the dry and cold winter and spring, there is much to discover on the trails, ridges and ravines, amplifying the chances of seeing something new and exciting; but for that to happen, you must look.
See you on the Mountain…
Doug