Defenders of Wildlife has set itself the goal of moving more than 100 endangered species up the federal recovery ladder over the next decade. Our “Road to Recovery” series will highlight several of these plants and animals and outline the challenges that lay ahead for improving their status.
As far as imperiled species go, the Oregon silverspot butterfly (Speyeria zerene hippolyta) has taken a dramatic turn for the better. This is saying a lot considering that in the 1990’s the population nearly crashed after a series of declines. Fortunately, environmental threats were recognized early enough to ensure its continued existence, and on October 15, 1980, the Oregon silverspot was federally listed under the Endangered Species Act as a threatened species. Since then, a zoo-based captive rearing and release program has been established so that new populations can thrive.
The silverspot is best known for being as beautiful as it is rare. It is a brown, yellow and orange butterfly with silver metallic spots and black veins that run up and down the dorsal side of its wings. Its smaller figure and darker wing coloration make it easily distinguishable from other species sharing its habitat. These inherited traits also help the silverspot to survive in its foggy and windy environments.
Historically, the Oregon silverspot once thrived in coastal habitat in Oregon, Northern California and Washington, but today it is found at only four locations in Oregon. What makes survival so tenuous for the silverspot is that it requires at least one of three types of grasslands. In order to successfully complete its development, silverspot larvae must have access to the early blue violet (Viola adunca) as a food source. This violet is confined to only three environments: coastal salt spray meadows, marine terrace meadows, and sandy dunes. The scarcity of this wild violet is what truly makes survival for this beautiful butterfly so difficult.
Currently, the known range of the silverspot butterfly is limited to select places in Lane, Tillamook, and Del Norte counties, all of which are in coastal Oregon. Even within such a limited environment, this rare insect still faces several threats. Like most specialized wildlife, agriculture, habitat fragmentation, and human development serve as the predominant threats to its existence. Off-road vehicles, livestock grazing, and fires are additional causes of population decline.
In 1998, the USFWS partnered with the Oregon Zoo and Woodland Park Zoo in Seattle, Washington to launch a population supplementation program. Adding zoo-raised butterflies to wild populations helps stop current populations from going extinct. Conservationists predict that around 2,000 butterflies are released each year on the Oregon coast. Without the help and support of these zoo-rearing programs, it is possible that many Oregon silverspot populations would now be extinct. This technique has proven to be effctive for the Oregon silverspot and with every bit of support it receives; its numbers will continue to rise.