Oregon silverspot population supplementation. (News from Zoos).

Habitat loss and degradation has greatly affected the Oregon silverspot (Speyria zerene hyppolyta) and the six different locations where this butterfly lives in the Pacific Northwest. The greatest affect has been on the silverspot's larval host plant, which now has to compete with non-native grasses. In 1980, the US Fish and Wildlife Service (USFWS) listed the Oregon silverspot as a threatened species. In 1998, the silverspot population at The Nature Conservancy's Cascade Head Preserve dropped to 57 individuals. This prompted the Oregon Zoo, The Nature Conservancy, Lewis & Clark University and USFWS to join forces and begin working on a captive rearing and release program to supplement the current populations.

The rapidly declining population at the Cascade Head Preserve made it the perfect location for the first supplementation. In September 1999, Nature Conservancy volunteers captured 10 adult butterflies. These 10 adults produced enough eggs that volunteers rereleased 107 adult butterflies into the wild. A survey of Cascade Head's silverspot population in 2000 showed a 21% increase over the 1999 population. Based on the success of the first release, the four organizations are planning additional releases at Cascade Head and possibly another site in 2002. [Source: Blair Csuti and David Shepherdson, Oregon Zoo]