San Bruno Elfin Butterfly

Callophrys mossii bayensis

Overview

Photo by: Larry Orsak

The San Bruno elfin inhabits rocky outcrops and cliffs in coastal scrub on the San Francisco peninsula in California. The San Bruno elfin is restricted to a few small populations, the largest of which occurs on San Bruno Mountain. Its habitat has been diminished by quarrying, off-road recreation, and urban development. Development pressures on the San Francisco peninsula continue to grow, and the major threats to the butterfly-increased urbanization in the area, and loss of habitat by road construction and rock and sand quarrying-reflect this. Grazing may have encouraged the growth of exotic plants in the area. In the early 1980s, a habitat conservation plan was developed to allow development on San Bruno Mountain while minimizing the adverse effects on the San Bruno elfin butterfly and other rare species in the area. This plan is currently being amended, which may result in further urban development.

Description

The San Bruno elfin (Callophrys mossii bayensis) is a small brownish butterfly in the Lycaenidae (gossamer wing) family. It has a wingspan between 7/8 - 1 1/8 inches (2.2 - 2.8 cm). The dorsal side of the male is grayish brown with a tan patch on hindwing inner margin and the female is light brown to tan with dark borders. The ventral side is coppery brown to purplish brown, marked by an uneven dark line that separates the inner and outer halves of the wings. On the hindwing, the inner half is darker than the outer half.

Life History

The adult flight period is late February to mid-April, with the peak flight period occurring in March and early April. Eggs are laid in small clusters or strings on the upper or lower surface of broadleaf stonecrop (Sedum spathulifolium). Larvae hatch from the eggs within 5-7 days of being laid.

Young larvae start to feed immediately by tunneling into the swollen succulent leaves. The first and second instars feed in this manner. Third and fourth instars move up to the flowers of the food plant and feed while they are tended by several species of ants that protect them from predators. These ants feed on honeydew produced by the larvae.

Pupation and pupal diapause (a dormant stage) take place in the loose soil and litter at the base of the larval food plant from June until February of the following year. The adults then emerge and mate. The adult food plants have not been fully determined. Montara Mountain colonies are suspected to use Montara Mountain manzanita (Arctostaphylos montaraensis) and huckleberry (Vaccinium ovatum).

Distribution

The San Bruno elfin is found in coastal mountains near San Francisco Bay in the fog-belt of steep north facing slopes that receive little direct sunlight. It lives near prolific growths of the larval food plant, stonecrop (Sedum spathulifolium), which is a low growing succulent. Stonecrop is associated with rocky outcrops that occur at 900-1075 feet in elevation.

First described in 1962 near San Francisco, colonies are known today on San Bruno Mountain (the largest population), Milagra Ridge, and Montara Mountain of San Mateo County; Mount Diablo in Contra Costa County; and near Alpine Lake and at Dillon Beach in Marin County.

Conservation Status

Current management on San Bruno Mountain and in other areas focuses on reduced pesticide use, careful recreation management, and vegetation management. Several areas from which populations had been previously extirpated are also being targeted for re-vegetation and reintroduction of the butterfly. Much of San Bruno Mountain is a county park. The park mangers are the lead people in amending the Habitat Conservation Plan.

Numbers appear to be stable based on 2000 monitoring of San Bruno Mountain HCP. There is no information from 2001 monitoring to support any change in status.

Conservation Needs

Working with landowners

Brookfield Homes is a developer with land on San Bruno Mountain that can be developed in exchange for protection of other land for the butterflies.

Education

Education sheets available at zoological facilities (e.g. zoos, aquariums, botanical gardens with butterflies, butterfly houses, natural history museums) or events at which BFCI partners participate are a valuable way to disseminate information about imperiled butterflies.

When schools and other youth organizations study biodiversity and species extinctions they typically use examples of charismatic megafauna (e.g. bald eagles) or exotic creatures from the tropics. However, vulnerable species found within the state or ecoregion in which students live provide an excellent opportunity to develop curricular materials with a direct link to the students' home region. In addition to classroom studies, students may be able to visit sites to see the butterflies, as well as talk to the scientists and land managers involved in the species' conservation.

Educational activities that school students and community members could do include:

studying butterfly (insect) life stages;
researching the special habitat needs of the San Bruno elfin;
corresponding or meeting with the biologists managing current San Bruno elfin sites;
visiting San Bruno elfin sites during adult flight season;
visiting captive breeding programs;
assisting scientists with on-site habitat management;
propagating and growing host plants for planting at butterfly sites or use in captive breeding programs; and
writing letters to decision makers to ensure that the San Bruno elfin receives adequate resources and protection.

Research

Information unavailable at time of publication.

Captive Rearing

Information unavailable at time of publication.

Recovery Plan

Draft San Bruno Elfin and Mission Blue Butterflies Recovery Plan. October 10, 1984.

There has never been a final recovery plan for the San Bruno elfin butterfly. Much of the information in the 1984 draft plan is outdated but would be a good starting point to develop a current recovery plan for the species.

Surveys at San Bruno Mountain are not intensive enough to make population estimates or determine trends. Implementation of essential grazing and prescribed fire has not occurred under the HCP, therefore habitat quality has likely declined which may be negatively affecting the butterfly species. Possible range expansion on Golden Gate National Recreation Area lands, and new localities identified on private lands in Pacifica.

The recovery plan for the San Bruno elfin butterfly also includes the Mission blue butterfly. The primary objective of the recovery plan is to protect, maintain, and enhance existing populations. The butterfly may be reclassified to Threatened when secure, self-sustaining colonies are established or reestablished on two identified sites and the San Bruno Mountain populations are secure. Delisting is contingent upon protection, maintenance, and/or expansion of current colonies and establishment of additional colonies.

Recovery Priorities

Protection of essential habitat from adverse development on and outside of San Bruno Mountain through cooperative agreements, easements, and other strategies;
Prevention of further habitat degradation from herbicides, pesticides, other toxicants, and off-road vehicle use. Habitat should be enhanced when possible by the removal of exotic plants and transplanting native flora;
Development and implementation of management plans for existing colonies of butterflies after gathering information on bionomics, determining reclassification and habitat criteria necessary for reclassifying and delisting, and evaluating management data for long term planning for butterfly management at all locations;
Reestablishment of populations in restored or rehabilitated habitats within historic range;
Enforcement of laws and regulations to protect these butterflies and their habitats; and
Development and implementation of an information and educational program.

More Info

USFWS Recovery Coordinator/Contact: Jim Browning, Sacramento Fish and Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, California 95825. Phone (916) 414-6600
Entomological Consulting Services, Ltd.: Richard Arnold, 104 Mountain View Court, Pleasant Hill, California 94523-2188, Phone (925) 825-3784

References

Arnold, R. A. 1980. Ecological studies on six endangered butterflies (Lepidoptera: lycaenidae); island biogeography, patch dynamics, and the design of habitat preserves. Berkeley, CA: Univ. of Calif., Berkeley. Ph.D. dissertation.
Arnold, R. A. 1983. Ecological studies of six endangered butterflies (Lepidoptera, Lycaenidae): island biography, patch dynamics, and design of habitat preserves. Univ. of Calif. Publications in Entomology. 99:1-161.
Brown, R. M. 1969a. A new subspecies of Callophyrys fotis from the San Francisco Bay area. Journal of the Lepidoptera Society. 23:95-96.
Brown, R. M. 1969b. Larva & habitat of Callophrys fotis bayensis. Journal of Research on the Lepidoptera. 8:49-50.
Emmel, J. F. and C. D. Ferris. 1972. The biology of Callophrys fotis bayensis. Journal of Research on the Lepidoptera. 26:237-244.
Powell, W. R. 1974. Inventory of rare and endangered vascular plants of California. Calif. Native Plant Society. Special Publication No. 1 (1st ed.).
Thelander, C. ed. 1994. Life on the edge: a guide to California's endangered natural resources. BioSystem Books. Santa Cruz, CA. p 420-421.
U.C. Berkeley, Essig Museum of Entomology. California's Endangered Insects San Bruno elfin page.
U.S. Fish & Wildlife Service. 1984. Draft San Bruno Elfin and Mission Blue Butterflies Recovery Plan. Portland, Oregon.
Sacramento Fish and Wildlife Office Endangered Species Division San Bruno elfin resources.

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Classification

Federal Endangered Species (Federal Register 41:22044; June 1, 1976)

State Status

No state designation beyond the federal classification.

Range

Critical Habitat

None designated

Acknowledgement

This profile was prepared by the Xerces Society for the Butterfly Conservation Initiative.