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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.”