2021 update on the Fender’s blue butterfly

January 2022

Fender’s blue butterfly (Icaricia icarioides fenderi) was listed as an endangered species in 2000 due to habitat fragmentation and prairie habitat loss throughout its range in the Willamette Valley, Oregon. Since 2016, IAE has played a major role in the conservation of Fender’s blue by conducting annual population surveys, restoring key habitat, and investigating population responses to restoration.

Willamette Valley weather conditions prior to the 2021 flight season (May) were relatively dry and warm compared to historic averages, resulting in 2021 being an interesting year for butterfly surveys in the Pacific Northwest. Fender’s population numbers fluctuate year to year due to multiple factors, including weather and habitat quality. Therefore, even though surveys in 2021 resulted in a slight decrease in two of the biggest populations surveyed, it is difficult to assess long-term population trends without multiple years of data.

Habitat restoration for Fender’s includes reducing invasive weeds and planting Kincaid’s lupine (the host plant for Fender’s) host and other native nectar plants. For Fender’s conservation, IAE is proud to work with the following funding and on-the-ground partners: the Army Corps of Engineers, US Fish and Wildlife Service (USFWS) National Wildlife Refuges, the USFWS Oregon Fish and Wildlife Office, Bureau of Land Management and Bureau of Reclamation, Benton County, Oregon Parks and Recreation Department, The Nature Conservancy, Greenbelt Land Trust, and Yamhill Soil and Water Conservation District.

IAE is grateful for funding provided by USFWS, and assistance from the Oregon Parks and Recreation Department. A huge thanks to all surveyors, including Rhiannon Cochrane, Christine Calhoun, Sally Villegas-Moore, S. Erskine, Kathleen Smith, Adam Kotaich, Andrew Esterson, Greg Fitzpatrick, Paul Hammond, Peter Moore, Gary Pearson, Dana Ross, Duncan Thomas and Tyler Hicks. We are also grateful to all public and private landowners who support surveys and manage their lands for Fender’s blue butterfly.

Curious if you are seeing Fender’s blue butterfly or look-alike silvery blue butterfly? Check out our previous blog post on distinguishing the two butterflies.