Fern Ridge home to largest population of endangered butterfly

Fern Ridge home to largest population of endangered butterfly
An endangered Fender’s blue butterfly rests on a Kincaid's lupine, a native prairie flower in western Oregon’s Willamette Valley. Prairie restoration efforts by the Willamette Valley Refuge Complex and private land partnerships have helped boost the butterfly’s numbers. Credit: Cheryl Schultz

VENETA, Ore. - The wild area around Fern Ridge Reservoir is home to the world's largest population of a species of butterly found only in Oregon's Willamette Valley that was previously believed to have gone extinct.

A 2012 U.S. Army Corps of Engineers survey estimates there are 3,769 Fender's blue butterflies at 11 sites near the reservoir west of Eugene, Ore. 2011 surveys estimated a population of 1,687 butterflies.

This species of butterfly was believed to be extinct from 1937 until it was rediscovered in 1989. It was first identified on Corps land in 1998. The species was listed as endangered in 2000.

The known population of Fender's blue butterflies has increased dramatically since their rediscovery, the Army Corps said. Corps biologists credit a combination of factors for the species' recovery, including restoration of prairie habitat by planting the butterfly's larval host, the federally protected Kincaid's lupine; control of invasive species; discovery of new populations; and improved monitoring methods.

Recovery of the Fender's blue butterfly and other prairie species of Western Oregon and Southwest Washington is a collaborative effort between the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, U.S. Bureau of Land Management, U.S. Geological Survey, Oregon and Washington state agencies, and a variety of non-governmental organizations.