Oregon Silverspot

Oregon silverspot habitat includes coastal salt-spray meadows, dunes, and montane grasslands. Much of the historical habitat for this butterfly has been threatened by habitat degradation and fragmentation, human development, invasive plant species encroachment, woody encroachment, and thicket accumulation.

• Remaining populations are few and extremely isolated from one another, and there is no documented gene flow between them.
• Though population size estimates are not available, researchers have reported population index data since 1990, which has been used as a relative measure to track population variation over time. In 1990, the total population index was ~2,500, and has declined to less than 1,000 over the past 30 years.
• Many fritillaries undergo reproductive diapause where females are less visible as they develop their eggs. It is uncertain whether this subspecies does, but some other Zerene fritillaries do.

Oregon silverspot  is federally listed as threatened  under the Endangered Species Act. At the state level, they are considered Strategy Species under the Oregon Department of Fish and Wildlife Oregon Conservation Strategy.

We analyzed four sites for the Oregon silverspot. We found three of the four experienced declines from 1991 to 2015 for two sites and 2002 for the other. Across the sites we saw no phenological shift in median activity date.