Species Recovery Projects
Oregon Silverspot Butterflies
Oregon Silverspot Butterflies (Speyeria zerene hippolyta) are listed as threatened under the U.S. Endangered Species Act. Once found on coastal headlands from southern Washington to northern California, they have disappeared from all but a handful of sites along the Oregon coast. In addition to habitat loss, their decline is also attributed to fire suppression and changes in grazing regimes, which allow invasive plants to out-compete the butterfly larva’s host plant, the early blue violet (Viola adunca).
Working in partnership with the U.S. Fish and Wildlife Service, Woodland Park Zoo and Oregon Zoo are captive-rearing butterflies from eggs to the pupa or chrysalis stage. The pupae are taken back to the coast to emerge as adult butterflies in the wild. The program maintains genetic variability in the population to increase the likelihood of the species’ recovery. The zoos are also considering captive breeding to increase the number of pupae produced.
The Nature Conservancy’s Cascade Head Reserve in southern Tillamook County is home to one of the surviving populations. Monitoring showed a dramatic population decline during the 1990s. The Nature Conservancy has initiated a habitat management plan that uses controlled burning to increase host plant populations.
