Speyeria zerene behrensii

Overview

Behren's silverspot is one of three threatened or endangered subspecies of Speyeria zerene (along with Myrtle's silverspot and the Oregon silverspot). The coastal prairie habitat of the butterfly, and the food plants of their larvae, are threatened primarily by commercial and residential development, competition from non-native vegetation, inappropriate levels of livestock grazing, off-road vehicle use, trampling by hikers and horses and overcollecting. The application of herbicides or other chemical agents, brush removal, or activities that raise heavy dust may also negatively impact this butterfly. Fire suppression has also likely played a role; the butterfly's host violet is better able to germinate when the overlying debris has been cleared away by periodic fires.

Description

Behren's silverspot (Speyeria zerene behrensii) is in the Nymphalidae, or brush-footed butterfly family. It is a medium-sized butterfly with a wingspan of approximately 5.5 cm (2.2 in). The dorsal wing surfaces are golden brown with numerous black spots and lines. Ventral surfaces are brown, orange-brown, and tan with black lines and distinctive silver and black spots. Basal areas of the wings and body are densely pubescent. Life History

Its preferred habitat is coastal terrace prairie. Behren's silverspot adults mate and lay eggs in the mid to late summer. The eggs hatch shortly thereafter and the 1st instar larvae enter a period of dormancy. The larvae resume feeding the following spring as their sole food plant, the blue violet (Viola adunca), begins its spring growth. Following 2-3 months of feeding and four molts, the larvae pupate. After a short pupation, the adults emerge, living approximately three weeks during which they live to mate and drink nectar.

Distribution

The historic range of Behren's silverspot butterfly extends along the northern coast of California, from the mouth of the Russian River in Sonoma County northward to the vicinity of Point Arena in Mendocino County. The butterfly is now only known from a single population at Point Arena. Conservation Status

The only known extant site was observed during the adult flight period in 1998. Adult butterflies were very scarce. Approximately 100 adults were observed at the same location in 1990. A population trend for the Behren's cannot be established at this time. The Arcata office of the U.S. Fish and Wildlife Service planned population surveys during 2001 to determine the Behren's status and distribution, and to characterize the habitat at the one extant and five known historical sites. The information is needed to develop the subspecies' recovery plan. The Arcata office deferred work on the recovery plan until 2002.

Conservation Needs

Working with landowners

Insufficient information available at time of publication.

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 Behren's silverspot;
• corresponding or meeting with the biologists managing current Behren's silverspot sites;
• visiting Behren's silverspot 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 Behren's silverspot receives adequate resources and protection.

Research

Insufficient information available at time of publication.

Captive Rearing

Insufficient information available at time of publication.

Recovery Plan

Draft Recovery Plan for Behren?s Silverspot Butterfly (650KB pdf) (Speyeria zerene behrensii), November 2003.

More Info

• USFWS Contact: David Solis, Arcata Fish and Wildlife Office, 1655 Heindon Road, Arcata, CA 95521 Phone: (707) 822-7201, Fax: (707) 822-8411
• Richard Arnold: Entomological Consulting Services, Ltd., 104 Mountain View Court Pleasant Hill, CA 94523-2188, (925) 825-3784

References

• U.C. Berkeley, Essig Museum of Entomology. California's Endangered Insects Behren's Silverspot page.
• USFWS Behrens Silverspot Species Profile.
• Federal Register final rule on listing.
• Behren's Silverspot Fact Sheet.

back to species profiles

Classification

Federal Endangered Species (Federal Register 62:64306; December, 5, 1997)

State Status

No state designation beyond the federal classification.

Range

Ca

Critical Habitat

None designated

Acknowledgement

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