The Oregon Zoo released 18 of its tiniest critters Tuesday Oregon silverspot butterflies reared at the zoo. It was the culmination of a summer-long release of 850 of the endangered butterflies, as part of a strategy to stabilize their population.
Were putting more butterflies into the ecosystem in hopes that theyll breed with wild butterflies and avoid local extinction, says Mary Jo Andersen, the zoos lead butterfly keeper.
Once common along the Oregon coast, the Oregon silverspot was listed as threatened by the U.S. Fish and Wildlife Service in 1980 one of two Oregon butterflies listed as threatened or endangered under the U.S. Endangered Species Act. By the 1990s, the species could only be found in four locations in the state.
They face a lot of obstacles, Andersen says. Development, motor vehicles, bad weather, pesticides, invasive species, natural predators like spiders.
In addition to releasing pupae, the Oregon Zoo raises and plants thousands of early blue violets, which serve as habitat for the Oregon silverspot.
When the caterpillars hatch, theyre tiny just about the size of Abe Lincolns nose on a penny, Andersen says. But they will eat more than 300 nickel-sized violet leaves before theyre ready to pupate.
The zoo works in partnership with Seattles Woodland Park Zoo, the Washington Department of Fish and Wildlife, Mission Creek Corrections Center for Women and the Portland-based Xerces Society for Invertebrate Conservation to help rear endangered butterflies and release them into the open.