The Fender’s blue butterfly was slow to emerge from the plastic tube, which had housed her until just a few minutes before inside a cooler. The low temperature had slowed the endangered butterfly to this languid pace, but upon emerging into the sun, she opened her wings (one of which is marked with a blue “1”) to bask away the chill.

After a brief pause, she was in the air, fluttering away on her dusty brown wings into the surrounding patch of purple Kincaid’s lupine, a threatened plant species in its own right and a critical host plant for the Fender’s blue. The flowers had been planted on Pigeon Butte in the William L. Finley National Wildlife Refuge years before, in a separate restoration effort, and their presence makes it possible for the Fender’s blue to take hold in the refuge.

“This is the first time we’ve had a planned release of Fender’s blue, ever,” said Paul Severns, a post-doctoral researcher at Oregon State University, who is using the release as a way to study which species of lupine the butterfly — which has been listed as an endangered species since 2000 — prefers as a host plant for its eggs and larvae.

“This is important because we don’t want to put Fender’s blue adapted to spur lupine on Kincaid (lupine),” he said. “What we do here can inform (the releases) we do in the future.”

Severns and U.S. Fish and Wildlife Service biologists released “Blue No. 1” and 49 other Fender’s blue butterflies Wednesday morning, the third of four releases of butterflies at the site. The releases began May 14 and concluded Thursday.

The biologists released a total of 180 adult butterflies at the site, mostly females who were marked with colored letters or numbers that enable researchers to track where they have been. Just 20 males were released, and they were unmarked.

Severns said the release of the males was simply a precaution to give any unmated females a potential partner.

Observing the reproduction of the butterflies is part of the study, Severns said.

The researchers also released around 40 Fender’s blue larvae to the site in April, and some of them have been observed at the site as adult butterflies.

Prior to the reintroductions, there were no Fender’s blue in the refuge, even though the area is part of the species’ historic range between Portland and Eugene. According to the U.S. Fish and Wildlife Service, the butterfly was believed to be extinct in 1937 until it was rediscovered in 1989.

Severns said he caught six of the butterflies at age 13, unaware they were supposedly extinct until he heard a news report that they had been rediscovered.

According to Severns, the species’ decline was caused by habitat loss as agriculture and urban development overtook the Willamette Valley’s native prairie.

The project to reintroduce the butterfly to the Finley refuge in south Benton County included clearing out invasive species such as blackberry and false brome, often with controlled burns, said Molly Monroe, a biologist with USFWS who works in the refuge.

The restoration efforts also have included planting lupine species and other native plants, she said.

The funds for the reintroduction and restoration projects are part of a four-year, $650,000 USFWS cooperative recovery grant that has also supported restoration of the Oregon chub, a native minnow which could soon be removed from the endangered species list. The funds also are being used for restoration work to benefit the Fender’s blue in Baskett Slough near Dallas.

Severns said the reintroduction of the Fender’s blue to Finley is significant because the handful of places where the species remains is on a mixture of public and private lands. While conservation easements protect the butterfly on private land, he said, Finley is public land that can be managed in perpetuity to protect the butterfly.

Some of the early signs are positive that the butterfly, which were collected from sites such as Willow Creek and Fern Ridge, will take hold at the site. The butterflies from the first batch released on Pigeon Butte were spotted there in the week following their release, and Severns and the USFWS biologists began finding Fender’s blue eggs, just a millimeter in diameter, the day after the first release.

“We are really happy about seeing eggs on both species of lupine,” Severns said.

Monroe said she is optimistic that the butterfly will take hold, and that in three to five years there will be a stable population of them.

“It’s really exciting,” she said. “It’s gratifying as a biologist to see restoration come to fruition and to see reproduction so soon.”

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Anthony Rimel covers K-12 education. He can be reached at 541-758-9526 or anthony.rimel@lee.net.