Silverspots: Oregon silverspot (Speyeria zerene hippolyta)

(Lepidoptera: Nymphalidae: Argynninae)

Profile prepared by Scott Hoffman Black and Mace Vaughan, The Xerces Society for Invertebrate Conservation

The Oregon silverspot is listed as a threatened species under the United States Endangered Species Act. It is found at a handful of sites scattered along the coast of northern California and Oregon. Development, grazing, and off-road vehicles are all to blame for this butterfly’s decline. Changes in fire regime, introduced plant species and pesticides are also threats. 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.

red list profile

conservation status

Xerces Red List Status: Critically Imperiled
Other Rankings
:
Canada – Species at Risk Act: N/A
Canada – provincial status: N/A
Mexico: N/A
USA – Endangered Species Act: Threatened
USA – state status: WA: Endangered
NatureServe: G5T1
IUCN Red List: N/A

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 silverspot is listed as a threatened species under the Endangered Species Act (Federal Register 45:44935-44939; 7/2/80).

Recovery Plan (ESA): Revised Recovery Plan for the Oregon silverspot butterfly Speyeria zerene hippolyta, August 22, 2001.

Critical Habitat (ESA): Designated; Federal Register 45:44935-44939 (7/2/80)

The Oregon silverspot is listed as endangered under state legislation in Washington. Neither California nor Oregon allow listing of insects under their respective endangered species statutes, so despite its precarious status, the Oregon silverspot has no protection from either state. The California Department of Fish and Game includes this butterfly on its Special Animals list.

description and taxonomic status

The Oregon silverspot is a member of the family Nymphalidae. Its wingspan is 27 mm (c. 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.

Speyeria zerene hippolyta (W. H. Edwards) 1879. Also known as the Hippolyta Fritillary.

life history

The Oregon silverspot requires one of three types of grasslands: coastal salt spray meadows, stabilized dunes, or montane meadows. The butterfly’s primary larval hostplant is the hookedspur 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. Important adult nectar plants include common yarrow (Achillea millefolium), western pearly everlasting (Anaphalis margaritacea), Canada goldenrod (Solidago canadensis), and Douglas aster (Symphyotrichum subspicatus var. subspicatus).

distribution

The Oregon silverspot previously inhabited suitable coastal habitat in from northern California to southern Washington. It is now extirpated from Washington state and found at only a handful of sites in California and Oregon.

This butterfly is the most northerly of a clade of three closely related subspecies that live on the Pacific coast. Myrtle’s silverspot (Speyeria zerene myrtleae; see Red List profile for more details) had a historic range along the coast from San Mateo County to Sonoma County, California, and the Behren’s silverspot (Speyeria zerene behrensii; see Red List profile for more details) had a historic range along the northern Californian coast.

threats and conservation needs

Threats

Historically, the coastal meadow habitats used by the Oregon silverspot were maintained in an early successional state by periodic fires, wind, and salt-spray, providing the open conditions required by the larval hostplant, hookedspur violet (Viola adunca). Although the wind and salt-spray continue to limit vegetation growth, recently, fires have been prevented because development has made them undesirable and the open meadow habitat has gradually been replaced by forest.

Coastal sites are under intense pressure from development and recreation. Much habitat has been destroyed by residential and commercial construction, the development of parks, and recreation activities such as off-road vehicles.

Conservation needs

The first priority must be to protect and manage the few remaining sites supporting extant populations of silverspots and to identify and protect other areas of suitable habitat. In Washington, the Department of Fish and Wildlife are actively searching for potential sites within the butterfly’s historic range in the southwestern tip of the state. Through a combination of vegetation management and plant propagation, the department is restoring suitable habitat.

Captive-rearing projects are underway at two regional zoos. The Oregon Zoo in Portland and the Woodland Park Zoo in Seattle are working in conjunction with the Nature Conservancy in Oregon to rear larvae that can be used to augment existing populations.

The U.S. Fish & Wildlife Service has developed an initial draft of Safe Harbor Agreement for Oregon silverspot butterfly. It will be a programmatic agreement to cover landowners within a 5 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 U.S. Fish & Wildlife Service office). The Nature Conservancy has agreed to be the master permit holder for the Safe Harbor Agreement.

Efforts should continue to survey suitable habitat and locate additional populations.

references

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 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. 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.

Peterson, M. 2002. The 2002 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.

additional resources

Recovery plan

U.S. Fish & Wildlife Service; Threatened and Endangered Species System: Oregon Silverspot Butterfly (Accessed 4/13/05)

U.S. Fish & Wildlife Service, Arcata Fish & Wildlife Office; Endangered Species Branch: Oregon Silverspot Butterfly (Accessed 9/23/08)

Washington Department of Fish and Wildlife; Oregon Silverspot Butterfly (Accessed 4/13/05)

University of California at Berkeley, Essig Museum of Entomology; California’s Endangered Insects: Oregon Silverspot Butterfly (Accessed 4/13/05)

Virginia Tech, Conservation Management Institute; Endangered Species Information System: Oregon Silverspot Butterfly (Accessed 4/13/05)

NatureServe Explorer (Accessed 4/13/05)

Oregon Zoo; Future for Wildlife Program (Accessed 4/13/05)

Woodland Park Zoo; Oregon Silverspot Butterfly Conservation Project (Accessed 9/17/08)

citation

Black, S. H., and D. M. Vaughan. 2005. Species Profile: Speyeria zerene hippolyta. In Shepherd, M. D., D. M. Vaughan, and S. H. Black (Eds). Red List of Pollinator Insects of North America. CD-ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate Conservation.

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