Prairie butterflies

Ecologists trying to boost the numbers of the fragile beauties campaign for federal protection, and the Oregon Zoo begins a captive-rearing program

The Oregonian—Science News
Wednesday, May 19, 2004

Dana Ross had suspicions about the hilltop meadow near Corvallis. The grassy area seemed to be a suitable home for a rarely seen prairie butterfly, but only a hike to the top would confirm it.

The insect ecologist got his answer in only a few steps. There, sitting on a dandelion, a Taylor’s checkerspot flashed its brilliant orange, black and white wings.

“I thought, ‘Wow, they’re here!’ ” Ross said. “My reaction was sheer delight. I expected to get up on top and possibly find them, but here was this beautiful fresh female next to the trail.”

The Corvallis resident quickly hiked to the hilltop, where he found an estimated 500 of the imperiled butterflies flitting through the meadow. Ross’s discovery last month in Benton County’s Beazell Memorial Forest is only the second population of Taylor’s checkerspot known to exist in Oregon after its rapid decline during the past century.

Researchers also found 1,150 butterflies in a previously known site in Benton County’s Fitton Green Open Space Natural Area. The number was about 500 more than last year.

The two sites are home to an estimated 75 percent of known Taylor’s checkerspots in the Northwest, said Scott Hoffman Black, executive director of the Xerces Society. The Portland-based conservation group is surveying the species’ population.

He said 12 other sites are in Washington, near Port Angeles and the south Puget Sound area, most with fewer than 50 individuals and two with about 100.

The discovery of the new site is a promising development in the push to save the Taylor’s checkerspot, which includes a conservation experiment at the Oregon Zoo and a legal battle to get the butterfly on the endangered species list.

This week, the Oregon Zoo begins a captive-rearing program for the butterfly with the Washington Department of Fish and Wildlife. The zoo will raise eggs of the Taylor’s checkerspot and another imperiled Northwest butterfly, the Mardon skipper, from sites in Washington. The eggs will mature to larvae, or caterpillars, then to pupae, which will be returned to the wild next spring to emerge as adults.

The zoo has been involved in a similar project since 1999 with the endangered Oregon silverspot, a coastal butterfly. Mary Jo Andersen, a zookeeper who manages the captive-rearing program, said the experiment will determine the best methods of raising the butterflies.
“They’re different than the silverspots, so I’m on a steep learning curve right now,” Andersen said.

Blair Csuti, the zoo’s conservation program coordinator, said the Oregon Zoo is eager to use its expertise in such efforts with Northwest species. He said the zoo contributed money to the Xerces Society’s survey and hopes the zoo lab’s captive-rearing effort can bolster populations at Washington sites.

Candidates for listing

The U.S. Fish & Wildlife Service has designated the Taylor’s checkerspot and the Mardon skipper as candidates for the federal endangered species list. But some conservation groups say candidate status does not do enough to protect the butterflies and their habitat.

A coalition of seven organizations has filed a notice of intent to sue the Fish & Wildlife Service to place the Taylor’s checkerspot, the Mardon skipper and the island marble butterflies on the endangered list. In December 2002, the groups submitted petitions to list the three butterflies as endangered, but the agency declined to take any action.

Joan Jewett, a spokeswoman for the Fish & Wildlife Service, said the agency’s lack of action on the petitions is “due to having too few resources and too much court-ordered work, not from a lack of wanting to protect species.”

Ted Thomas, a senior ecologist for the Fish & Wildlife Service in Lacey, Wash., who has studied the butterflies, said the candidate status recognizes that “these species are in trouble.”

“If we can get enough people doing positive things for these species, maybe we’re going to find new populations and enhance and restore habitat to a point where maybe we could preclude the need to list,” Thomas said.

All of the parties agree that restoring the butterflies’ grassland prairie habitat is essential. Less than 3 percent of the habitat remains in Oregon and Washington, the victim of development, pesticides, grazing, forest encroachment and invasive non-native plants such as Scotch broom, Himalayan blackberry and a few grasses.

Other rare breeds

The small tawny-orange Mardon skipper is found in small populations at 37 known sites in south Puget Sound, the southern Washington Cascades and the Soda Mountain area of the Cascade-Siskiyou National Monument. The white and green island marble is found on Washington’s San Juan Island.

The Taylor’s checkerspot, Euphdryas editha taylori, once could be found in grasslands throughout the Willamette Valley, Puget Sound and south Vancouver Island in British Columbia. No populations are known to exist in British Columbia.

Hoffman Black said 7,000 Taylor’s checkerspots at Fort Lewis in Washington vanished in the mid-1990s, possibly because drought conditions caused by an El Nino wiped out its host plantain plant, Plantago lanceolata, which the butterfly’s larvae feed on.

Another key host plant for the larvae is a drought-resistant paintbrush, Castilleja hispida, a native species.

“The paintbrush is not found widely any more,” said Hoffman Black, an ecologist and entomologist. “The butterfly seems to have switched to the non-native plantain, which is a common plant throughout prairie areas in Washington and Oregon.

“One of the interesting things we need to look at is whether we can take the butterflies that are dependent on the non-native host plant, rear them and release them into sites where the native host plant is.”

Survey in Washington

Dave Hays, a biologist with the Washington Department of Fish and Wildlife, said surveys are being taken this month of the Taylor’s checkerspot in Washington.

“We have had a focus in the south Puget Sound with preserving the grasslands to try to recover these dwindling species,” said Hays.

He is pleased that the Oregon Zoo will be developing methods for rearing the butterflies in captivity. “Anything that we can do to make them more abundant will help them in the long run,” he said.

Hoffman Black said he hopes that the Taylor’s checkerspot eventually will join two Northwest butterflies already on the federal list: the Oregon silverspot, a coastal butterfly designated as threatened, and the Fender’s blue, a prairie butterfly in the Willamette Valley listed as endangered. Recent surveys have found that restoration of prairie habitat has helped boost populations of the Fender’s blue, which is dependent on Kincaid’s lupine, a plant listed as threatened.

“Getting the butterfly on the endangered list is just one avenue we’re working on to protect the checkerspot,” Hoffman Black said. “Working with private landowners, state and local agencies as well as other conservation groups is also important.

“It’s a bigger issue than just one butterfly. If you protect these high-quality prairie sites, you help all the species that need or use them, from songbirds to insects.”