PORTLAND, Ore. (KOIN) – An Oregon butterfly species that was once thought to be extinct has rebounded enough to be removed from the endangered species list.

The U.S. Department of Fish and Wildlife announced that the Fender’s blue butterfly’s status will officially be changed from “endangered” to “threatened” on Feb. 13. Supervisor for the U.S. Department of Fish and Wildlife’s Oregon office Craig Rowland called the transition a “tremendous success story” and said that the butterfly is now “on the road to recovery.”

“We’ve only reached this point of being able to downlist because of successful partnerships with landowners, conservation agencies, businesses, other agencies, and the work of our national wildlife refuges to conserve the Fender’s butterfly,” Rowland said. “This is yet another species that is making incredible strides in Oregon.”

While the Fender’s blue butterfly was considered extinct in 1937 due to human development in the Willamette Valley, small populations of the butterfly were rediscovered in 1989. The insect was subsequently placed on the endangered species list in 2000. 

Studies cited by the Center for Biological Diversity show that approximately 4,000 Fender’s blue butterflies were known to exist in the wild when it was placed on the endangered species list.

Thanks to conservation efforts through the Endangered Species Act, scientists say, the butterfly’s habitat range has since doubled. In 2016, a survey estimated that the butterfly’s population had grown to about 29,000.

The Fender’s blue butterfly can now be found in Benton, Lane, Linn, Polk, Washington and Yamhill Counties from mid-April to late June.

The butterfly’s resurgence, the USDFW said, is also helping with the revival of endangered plants that are pollinated by the Fender’s blue, like the Kincaid’s lupine and the Willamette daisy.

The successful recovery process is largely due to the discovery that prescribed burns can help clear prairies of invasive plants and grasses that crowd the soil and impact the growth of the Kincaid’s lupine — the Fender’s blue butterfly’s plant of choice for laying its eggs.

“Fender’s blue butterflies are completely dependent upon threatened Kincaid’s lupine, a flowering plant that is the butterflies’ primary host,” the Center for Biological Diversity said. “The butterfly remains highly vulnerable to climate change, as rising temperatures harm the lupine and other plants it needs to survive.”

On the 50th anniversary of its inception, the Endangered Species Act has helped to restore more than 50 endangered species to healthy populations. Quinn Read, the Oregon policy director for the Center for Biological Diversity, said that the protective environmental laws are directly responsible for success stories like the Fender’s blue butterfly.

“The Endangered Species Act has ensured the full recovery of more than 50 species, and the Fender’s blue is now well on its way,” Read said. “This little butterfly was nearly lost to Oregon, but now we can celebrate its recovery along with the 50th anniversary of the landmark law that saved this species.”