U.S. Fish & Wildlife Service

Sacramento Fish & Wildlife OfficeServing the people, conserving the fish, wildlife, and plants of California

A Unit Of The Pacific Southwest Region

Site Visit Insights from Joseph Terry and Valerie Hentges

August 1, 2017

1 / 13
Photo of Biologists Joseph Terry and Valerie Hentges
Sacramento Fish and Wildlife Office Biologists Joseph Terry and Valerie Hentges invite you to join them on a site visit to San Bruno Mountain. Photo credit: Veronica Davison, USFWS.
2 / 13
Photo of Romona Arechiga leading biologists during site visit
San Mateo County Natural Resources Manager Ramona Arechiga leads biologists on the San Bruno Mountain site visit. Photo credit: Veronica Davison, USFWS.
3 / 13
Photo of checkerbloom flower
The checkerbloom flower (Sidalcea malveflora) is one of the many wild flowers that support San Bruno Mountain butterflies. Photo credit: Veronica Davison, USFWS.
4 / 13
Photo of fiery skipper butterfly
Named for their quick, skipping flight, the fiery skipper butterfly (Hylephila phyleus) is often mistaken for a moth. Photo credit: Veronica Davison, USFWS.
5 / 13
Photo of California blackberry
The California blackberry (Rubus ursinus) is native to California. Photo credit: Veronica Davison, USFWS.
6 / 13
Photo of Mediterraneean lineseed
Mediterranean lineseed (Bellardia trixago) is a non-native flowering plant found on San Bruno Mountain. Photo credit: Veronica Davison, USFWS.
7 / 13
Photo of Biologist Claudia Funari
Sacramento Fish and Wildlife Office Biologist Claudia Funari spots an endangered San Bruno elfin butterfly larva nestled in a Stonecrop (Sedum spathulifolium). Veronica Davison, USFWS.
8 / 13
Photo of San Bruno elfin butterfly larva is almost camouflaged on this Stonecrop
The San Bruno elfin butterfly larva is almost camouflaged on this Stonecrop (Sedum spathulifolium) plant. Photo credit: Veronica Davison, USFWS.
9 / 13
Photo of host plant Stonecrop
Stonecrop (Sedum spathulifolium) is a San Bruno elfin butterfly host plant. Photo credit: Veronica Davison, USFWS.
10 / 13
Photo of wildflowers
Wildflowers add an array of colors to San Bruno Mountain. This seaside daisy (Erigeron glaucus) is one of many found onthe mountain. Photo credit: Veronica Davison, USFWS.
11 / 13
Photo of tiny egg left behind on a summer lupine
Mission blue butterflies (Icaricia icarioides missionensis) rely on San Bruno Mountain’s native plants—look closely to see the tiny egg left behind on a summer lupine (Lupinus formosus) leaf by this endangered species. Photo credit: Veronica Davison, USFWS.
12 / 13
Photo of endangered mission blue butterfly
The endangered mission blue butterfly (Icaricia icarioides missionensis) is a small delicate butterfly that was first collected in San Francisco's Mission District in the 1930s. Photo credit: Veronica Davison, USFWS.
13 / 13
Photo of San Bruno Mountain
San Bruno Mountain offers important open space habitat for plant and wildlife species in the Bay Area. Photo credit: Veronica Davison, USFWS.

Site visits are critical to helping Sacramento Fish and Wildlife Office (SFWO) biologists learn more about species and their habitats. The trips often take them into areas most people do not have a chance to explore, including public and privately-owned restricted sites, as well as some remote and hard-to-reach areas. “Site visit Insights” provides a behind-the-scenes perspective of wildlife biology, featuring photographs and interesting discoveries and happenings SFWO biologists experience in the field.

Wildlife Biologists: Joseph Terry and Valerie Hentges
Site visit location: San Bruno Mountain, Brisbane, California

What was the purpose of the site visit?
San Bruno Mountain Habitat Conservation Plan was the first Habitat Conservation Plan in the nation (circa 1982). The Habitat Conservation Plan for San Bruno Mountain protects the ecosystems for threatened and endangered species. In this case, one of the core habitat areas for the endangered mission blue, callippe silverspot, and San Bruno elfin butterflies, and the recently reintroduced threatened Bay checkerspot butterfly.

The purpose of the site visit was to view the difficulties and constraints the San Mateo County Parks Department faces in restoring and managing habitat for the endangered butterflies on San Bruno Mountain given the budgetary and other constraints under the Habitat Conservation Plan. Spring usually has the benefit of more sightings of some of these butterflies during their flight season due to the overlap in mid-May of the end of the flight season for the mission blue butterfly, the beginning of the flight season for the callippe silverspot butterfly, and the larval emergence of the San Bruno elfin butterfly.

Where did you go?
San Bruno Mountain, which is part of the San Mateo County Parks System in northern San Mateo County, California.

What partners were you working with and what is the nature of SFWO’s partnership with them?
San Mateo County Parks Department is the lead agency for implementation of the San Bruno Mountain Habitat Conservation Plan. Creekside Science provides technical expertise in restoring, managing, and monitoring habitat for the endangered butterflies on San Bruno Mountain and the translocation of endangered butterflies to and from San Bruno Mountain. The Sacramento Fish and Wildlife Office is on the Technical Advisory Committee for the San Bruno Mountain Habitat Conservation Plan and provides guidance in restoring and managing habitat for the endangered butterflies.

What did you learn from this site visit that you didn’t know before?
Bay checkerspot butterfly larvae were successfully reintroduced to the annual grasslands of San Bruno Mountain this year from their core population in the serpentine grasslands of Santa Clara County. Even though native dwarf plantain is its primary host plant in the serpentine grasslands of Santa Clara County, the larvae adapted to the different habitat conditions of San Bruno Mountain by learning to forage on the non-native English plantain; which is more prevalent. Thatch from invasive annual grasses is one of the primary threats to the endangered butterflies of San Bruno Mountain that has yet to be addressed.

What surprises did you encounter during the site visit?
Weather conditions are highly variable on San Bruno Mountain which makes scheduling butterfly monitoring difficult. During our visit, it was extremely windy on some parts of the mountain—which can make it difficult for the butterflies to fly. The endangered butterflies rely on natural disturbances, like fire and grazing, to maintain their grassland habitat and prevent encroachment of native shrubs. Prescribed burns are prohibited on San Bruno Mountain due to safety concerns because of nearby homes and the San Francisco airport flight path. To help with land management, San Mateo County Parks Department will be setting up a technical advisory team to evaluate the feasibility of reintroducing cattle grazing to San Bruno Mountain. Grazing controls invasive grasses and the encroachment of native shrubs that threaten the grassland habitat of the endangered butterflies.

Last updated: May 9, 2018