As season warms up, zoo rears and releases endangered butterflies
The Oregon Zoo's butterfly conservation lab is aflutter with activity this week, as keepers balance the complex needs of two imperiled species native to the Northwest.
"This is a critical time of year for both Taylor's checkerspot and Oregon silverspot butterflies, so there's a lot going on," said Mary Jo Andersen, a keeper who has logged long hours tending to the rare and delicate creatures during all stages of their development. "It's magical chaos right now."
Although the current buzz of activity may seem chaotic, it's actually highly organized. Keepers adhere to meticulous timetables for waking, releasing, breeding and feeding two species of butterfly, which develop according to different schedules. Detailed manuals and yearlong schedules are necessary to ensure each egg has the best possible chance of becoming a mature butterfly.
This level of care is crucial: the Taylor's checkerspot butterfly is listed as endangered in Washington state (Oregon does not include invertebrates on its list) and is under review for federal listing; the Oregon silverspot is listed as threatened by the U.S Fish and Wildlife Service. While the butterflies themselves are small, they are important pollinators and have a big impact on their ecosystem.
Since March, Oregon Zoo keepers have awakened more than 3,000 checkerspot caterpillars from their winter dormancy, transferring 2,000 of them to the Washington Department of Fish and Wildlife for release on prairies near Olympia, where some of the region's best habitat remains. Releasing larvae reared at the zoo is part of WDFW's ongoing effort to reestablish the species at sites where it once was abundant.
Caterpillars remaining at the zoo finished their transformation and emerged from chrysalises into butterflies. Adult butterflies were bred and are now laying eggs to start the process all over again for next year.
"As a zookeeper and animal lover, it's wonderful to be involved in a conservation process that puts thousands of animals back into the wild each year," Andersen said.
After eight years of working to grow the number of endangered checkerspots, the effects have been noticeable.
"Biologists are reporting higher numbers of checkerspot larvae and butterflies in the field and their distribution is expanding," said Karen Lewis, zoo conservation research associate. "We are optimistic about the project's continued success."
In the next two weeks, around 2,800 silverspots will awake from their dormancy. For the 13th year, they will be released along the Oregon coast. To help maintain wild populations, the zoo also plants Viola adunca, the only type of vegetation Oregon silverspot caterpillars can eat. With most of their natural habitat destroyed or threatened by development, maintaining a food supply is critical to stabilizing silverspot populations.
The Oregon Zoo works in partnership with and receives funding from the Washington Department of Fish and Wildlife and Joint Base Lewis-McChord and its Army Compatible Use Buffer program to rear checkerspots and release them into the wild. Additional project partners include the U.S. Fish and Wildlife Service, The Evergreen State College, Mission Creek Corrections Center for Women, and the Xerces Society.
For silverspots, the Oregon Zoo partners with the U.S. Fish and Wildlife Service, the Woodland Park Zoo in Seattle, The Nature Conservancy, the Oregon Department of Forestry, and the Oregon Department of Fish and Wildlife.