Oregon Silverspot Butterfly

Speyeria zerene hippolyta

Overview

The Oregon silverspot butterfly (Speyeria zerene hippolyta) is listed as a threatened species under the United States Endangered Species Act. Patches of Oregon silverspot habitat occur in Oregon, Washington and California. Development, grazing and off-road vehicles are all to blame for this butterfly's decline. Changes in fire regime, introduced plant species and pesticides also threaten this butterfly.

Historically, the coastal meadow habitats used by the Oregon silverspot were maintained in an early successional state by periodic fires. Fires prevent trees and shrubs from overshadowing low-growing plants such as violets (genus Viola). Recently, fires have been prevented because development has made them undesirable. Thus, meadow habitat has gradually been replaced by forest. Recognition of the role of fire and other periodic disturbance in the maintenance of Oregon Silverspot habitat has allowed appropriate management strategies to be enacted and the butterfly's future is relatively bright.

Description

This butterfly is a member of the family Nymphalidae. It belongs to one of fifteen subspecies of Speyeria zerene Boisduval. The silverspot has wings as wide as 27 mm (1 in) for males and 29 mm (1.1 in) for females. The silverspot has orange and brown markings with black veins and spots on the dorsal side of the wings, and bright metallic silver spots on the ventral sides.

Life History

The silverspot requires one of three types of grasslands: coastal salt spray meadows, stabilized dunes, and montane meadows. The Oregon silverspot butterfly's primary source of food is the western blue violet (Viola adunca). Adults appear throughout the late summer and early fall to mate. The eggs are laid during the fall and hatch shortly thereafter. The larvae feed for a short time in the fall and then enter a dormant state in which they spend the winter. In the spring the larvae resume feeding until the late spring or summer when they pupate. Their pupation time is short and adults soon emerge to continue the cycle.

Distribution

The Oregon silverspot once inhabited suitable coastal habitat in Washington, Oregon and Northern California. It is now found at only four sites in Oregon.

Conservation Status

The Nature Conservancy (TNC) has conducted annual population censuses for Oregon silverspot butterflies at the four central coast sites in Oregon since 1990. Three of these populations remain in a decline. The only population not showing a decline in the 2000 surveys was the one that is being augmented with captive-propagated individuals. (It is important to note that TNC's 11-year data set coincides with a period in which both habitat quality and silverspot numbers may be far below historic levels.) Spread of non-native grasses has exacerbated habitat loss by reducing the availability of native plant foods for the butterfly. In 2001, augmentation also occurred at a second site. The Oregon Zoo in Portland, OR and Woodland Park Zoo in Seattle, WA have been active participants in silverspot field conservation efforts and ex situ propagation of this species for several years.

Conservation Needs

Working with landowners

The USFWS has developed an initial draft of Safe Harbor Agreement for the Oregon silverspot butterfly. It will be a programmatic agreement to cover landowners within a five-mile stretch of dispersal habitat between two occupied populations on the Oregon coast in Lane County. Habitat restoration is already occurring on two private parcels (both of whom have already received a 'baseline determination' from the USFWS office). The Nature Conservancy has agreed to be the master permit holder for the Safe Harbor Agreement.

Education

Education sheets available at zoological facilities (e.g. aquariums, botanical gardens with butterflies, butterfly houses, or natural history museums) or events at which BFCI partners participate are always a valuable way to disseminate information about imperiled butterflies. Oregon Zoo and Woodland Park Zoo staff have created Oregon silverspot education resources for outreach programming both on zoo grounds and in their communities. The silverspot provides a unique opportunity for kids to connect with imperiled species in their local region. In addition to classroom studies, students may be able to visit sites to see the butterflies (where appropriate), 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 Oregon silverspot;
  • corresponding or meeting with the biologists managing current Oregon silverspot sites;
  • visiting Oregon 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 Oregon silverspot receives adequate resources and protection.

Research

Currently, scientists are engaged in an active research program to study the habitat needs of this butterfly. Staff at Oregon Zoo and Woodland Park Zoo are conducting research to assess the success of their captive rearing efforts as well.

Captive Rearing

The Oregon Zoo and the Woodland Park Zoo have an active captive rearing program. The Nature Conservancy is working with them to stabilize populations on Conservancy lands.

Recovery Plan

Revised Recovery Plan for the Oregon Silverspot Butterfly (10MB pdf), August 22, 2001.

The Oregon Silverspot Recovery Plan was finalized in 2001. The objective of this plan is to delist the federally threatened silverspot. Delisting can be considered when all of the following conditions have been met:

  • At least two viable Oregon silverspot butterfly populations exist in protected habitat in each of the following areas: Coastal Mountains, Cascade Head, and Central Coast in Oregon; and Del Norte County in California; and at least one viable Oregon silverspot butterfly population exists in protected habitat in each of the following areas: Long Beach Peninsula, Washington and Clatsop Plains, Oregon. This includes development of comprehensive management plans.
  • Habitats are managed long-term to maintain native, early successional grassland communities. Habitat management maintains and enhances early blue violet abundance, provides a minimum of five native nectar species dispersed abundantly throughout the habitat and flowering throughout the entire flight period, and reduces the abundance of invasive non-native plant species.
  • Managed habitat at each population site supports a minimum viable population of 200 to 500 butterflies for at least 10 years.

Recovery Priorities

Summary of Recovery Activities Needed:

  • Protect and enhance existing habitat in each of six habitat conservation areas (Long Beach Peninsula, Clatsop Plains, Coastal Mountains, Cascade Head, Central Coast, and Del Norte).
  • Determine ecological requirements, population constraints, and management needs of the Oregon silverspot butterfly. Refining understanding of habitat requirements, understanding of factors that affect population dynamics and persistence of the Oregon silverspot butterfly and determining optimum methods of re-introducing butterflies into restored or unoccupied habitat are all important parts of this task. Determining methods of reducing impacts of impingement of butterflies by vehicles along Highway 101 should be completed as well.
  • Monitor the butterfly's population and habitat status. Developing monitoring guidelines and techniques for tracking population status and tracking habitat status and habitat management activities are important for completion of this task. This task may require augmentation/reintroduction, if appropriate, based upon population trends, habitat availability, and life history factors.
  • Reduce take.

For more information

  • USFWS Recovery Coordinator/Contact: Amy Horstman, Oregon Fish and Wildlife Office, 2600 S.E. 98th Ave., Portland, Oregon 97266 Phone (503) 231-6179.
  • The Nature Conservancy of Oregon: Debbie Pickering, Oregon Coast Stewardship Ecologist, 821 S.E. 14th Avenue, Portland, Oregon 97214 Phone (503) 230-1221.
  • Oregon Zoo: David Shepherdson, Conservation Program Scientist, 4001 SW Canyon Road, Portland, Oregon 97221-2799 Phone (503) 220-5765, shepherdsond@metro.dst.or.us
  • Woodland Park Zoo: Erin Sullivan, "Bug" World Keeper, 601 N. 59th Street, Seattle, Washington 98103-5858 Phone (206) 684-4880, Erin.Sullivan@zoo.org

References and Resources

  • Arnold, R.A., 1988. Ecological and behavioral studies on the threatened Oregon silverspot butterfly at its Rock Creek, Cascade Head, Mt. Hebo, and Clatsop Plains populations in Oregon. U.S. Fish and Wildlife Service, Endangered Species Office. Olympia, WA.
  • Dean, J.M. 2000. The 2000 survey for the presence of the Oregon silverspot butterfly, Speyeria zerenehippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. Submitted to U.S. Fish and Wildlife Service, Portland Field Office, Portland, Oregon. The Nature Conservancy, Portland, Oregon. 15 pp.
  • Eid, N. 1999. The 1999 survey for the presence of the Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. Submitted to U.S. Fish and Wildlife Service, Portland Field Office, Portland, Oregon. The Nature Conservancy, Portland, Oregon. 14 pp.
  • Hammond, P.C. 1991. The 1991 report of the Oregon silverspot butterfly (Speyeria zerene hippolyta) Camp Rilea, Clatsop County, Oregon. Oregon State Military Department, Oregon National Guard. 46 pp.
  • Lesh, T. 2001. The 2001 survey for the presence of the Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. Submitted to U.S. Fish and Wildlife Service, Portland Field Office, Portland, Oregon. The Nature Conservancy, Portland, Oregon. 14 pp.
  • McCorkle, D.V. and P.C. Hammond. 1988. Biology of Speyeria zerene hippolyta (Nymphalidae) in a marine modified environment. Journal of the Lepidopterist's Society. 42(3): 184-195.
  • McCorkle, D.V., P.C. Hammond, and G. Pennington. 1980. Oregon silverspot butterfly (Speyeria zerene hippolyta). Ecological Investigation Report. USDA Forest Service, Siuslaw National Forest. 116 pp.
  • McIver, J., S. Muttillinja, D. Pickering, and R. VanBuskirk. 1991. Population dynamics and habitat selection of the Oregon silverspot butterfly (Speyeria zerene hippolyta): a comparative study at four primary sites in Oregon. Report to the U. S. Dept. of Agriculture, Forest Service, Siuslaw National Forest, Corvallis, Oregon. 61 pp.
  • Patterson, J. M. 2002. The 2001 survey for the presence of the Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. Submitted to U.S. Fish and Wildlife Service, Portland Field Office, Portland, Oregon. The Nature Conservancy, Portland, Oregon. 11 pp.
  • Pickering, D. and C. Macdonald. 1994. 1992-93 Oregon silverspot butterfly habitat surveys Clatsop Plains, Mt. Hebo, Cascade Head, and Rock Creek/Bray Point. Submitted to U. S. Fish and Wildlife Service, Portland Field Office, Portland, Oregon. The Nature Conservancy, Portland, Oregon. 16 pp.
  • VanBuskirk, R. 1993. Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae): Clatsop Plains and central Oregon Coast Research. University of California. The Nature Conservancy, Portland, OR. 36 pp.
  • VanBuskirk, R. 1998. Survey for the presence of the Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae) on the Clatsop Plains in 1998. University of California. The Nature Conservancy, Portland, OR. 13 pp.
  • USFWS Oregon silverspot butterfly page
  • Washington Department of Transportation Oregon silverspot resources
  • Woodland Park Zoo Oregon silverspot resources

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Classification

Federal Threatened Species (Federal Register: 45:44935; July 2, 1980)

State Status

Washington State Species of Concern

Range

OR

Critical Habitat

Designated in Federal Register: 45:44935; July 2, 1980

Acknowledgement

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