Detroit Zoo and Michigan DNR Release Karner Blue Butterfies

The Detroit Zoo and Michigan Department of Natural Resources (DNR) will release captive-reared federally endangered Karner blue butterflies at the Petersburg State Game Area (PSGA) in Monroe County on Wednesday, July 9, at 11 a.m. The release is part of the United States Fish and Wildlife Service’s Karner Blue Butterfly Recovery Plan and PSGA Master Plan.

“We’re very excited about releasing the butterflies in Michigan because we've been working toward this point for the past three summers,” said Detroit Zoo Associate Curator of Invertebrates Laura Palombi. “This is a test of our ability to restore an ecosystem.” Palombi will share the Karner blue butterfly conservation success story at a public lecture at the Zoo’s Ford Education Center Theatre on Wednesday, July 9, at 7 p.m. Admission is free.

The Karner blue (Lycaeides melissa samuelis) is a small butterfly with a wingspan of about one inch which lives in oak savanna habitats ranging from Minnesota to Maine. The butterfly, once common in Michigan, has not been seen in Southeast Michigan since 1987 when it was last observed at the PSGA.

The caterpillars of the Karner blue feed exclusively on the leaves of wild lupine (Lupinus perennis). Fire suppression – along with the conversion of land to agriculture, residential areas and other uses – has severely reduced the range and availability of wild lupine.

The ecosystems historically were maintained by fires, which kept the open savanna from turning into forest. The DNR has been using burns and vegetation removal to restore the habitat at PSGA, while the Detroit Zoo has planted seeds and plugs of lupines and plant species to provide nectar for the adult Karner blue butterflies.

“Our habitat management activities at the Petersburg State Game Area, such as brush clearing, mowing and burning, have been very effective in restoring the traditional savanna habitat conditions where the butterflies can thrive,” said Joe Robison, DNR wildlife biologist. “By hand-seeding and hand-planting plugs of its preferred vegetation, the site has become more Karner blue-friendly.”

Adult female Karner blue butterflies were collected in late May and transported to a greenhouse at the Detroit Zoo, where they are fed daily and held in individual enclosures over lupine plants on which they lay their eggs. Each female can lay over 100 eggs. The caterpillars that hatch are monitored daily until they reach the chrysalis stage, which takes about three to four weeks. About 10 days later adult butterflies emerge and within days will be transported to the PSGA release site.

The plan calls for the continued release of the descendants into the wild over the next four to six years. Zoo staff and volunteers will monitor the population at the release site annually and will continue to release captive-reared butterflies until the population at PSGA is considered self-sustaining. According to the federal recovery plan, a minimum viable population consists of at least 3,000 individuals.

“The long-range goal of this program is to protect existing populations of Karner blues and reestablish new, viable populations within their historical range,” said Palombi. “The ultimate goal is to eventually remove Karner blue butterflies from the federal list of endangered species.”

The Detroit Zoological Society is a non-profit organization that operates the Detroit Zoo and Belle Isle Nature Zoo. Situated on 125 acres of naturalistic exhibits, the Detroit Zoo is located at the intersection of Ten Mile Road and Woodward Avenue, just off I-696, in Royal Oak. The Detroit Zoo is open daily 10 a.m. to 5 p.m. April through October (open at 9:30 a.m. Memorial Day through Labor Day) – with extended hours until 8 p.m. Wednesdays during July and August – and 10 a.m. to 4 p.m. November through March. Admission is $11 for adults 13 to 61, $9 for senior citizens 62 and older, and $7 for children ages 2 to 12; children under 2 are free. For more information, call (248) 541-5717 or visit www.detroitzoo.org. The Belle Isle Nature Zoo is open daily 10 a.m. to 5 p.m. year-round and provides educational programming with interpretive staff support from the Huron-Clinton Metroparks. For more information, call (313) 852-4056.