Fender’s Blue Butterfly Prairie Habitat

June 23, 2012 · 3 comments

As if Henry wasn’t busy enough with horseshoeing and beekeeping, he also does habitat monitoring and restoration work locally as a contractor for the Marys River Watershed Council and United States Fish and Wildlife Service (USFWS). For the past month or so, he’s been spending a day or two a week counting butterflies, quantifying nectar resources, and assessing a bunch of different prairie sites in our area.

Endangered Fender’s blue butterflies (Icaricia icarioides fenderi–above) are native to Benton County (where we live) and a few other areas in Oregon’s Willamette Valley. A very small portion of historic Willamette Valley praires, critical for Fender’s blue survival, remain undeveloped or unplanted to conifer trees in the present day. Fender’s blue habitat, however, is difficult to “protect” because many of the nectar species need disturbance to thrive and often do better with some amount of grazing, farming, or logging.

One day last week, Henry was surveying a site just a few miles down the road from our house, so the kids and I went down to visit him in action.













Fender’s blues coexist with their primary host species, Kincaid’s lupine (Lupinus oreganus–above left), which is also endemic to this region and officially listed as “threatened”.  Adult Fender’s blues drink nectar from several other native wildflowers such as  checker mallow (Sidalcea virgata), oregon sunshine (Eriophyllum lanatum), Oregon toughleaf iris (Iris tenax), cat’s ears lilies (Calochortus tolmiei) and various species of vetch. Butterfly populations fluctuate greatly every year with seasonal weather conditions, and this year happens to be a fairly bad one for them. We’ve had way above average rainfall this spring, limiting butterfly flight opportunities.

This particular site also had a fair bit of invasive scotch broom (Cytisus scoparius–above right) present. Showy scotch broom was brought into the area in the 1930s and has been outcompeting native plants ever since. After we visited, a corrections work crew came to the site and pulled much of the scotch broom in an effort to maintain prairie habitat.

Native toughleaf iris was also in full bloom.













Fender’s blues weren’t the only butterflies on the site. We caught a couple Propertius Duskywings (Erynnis propertius–above left) in the act.

This Kincaid’s lupine (above right) had been parasitized, probably by a wasp, and the larvae were living in the furled leaves.

Henry was more or less done with his tasks for the day when we met up with him, so we just took a nice hike across the prairie.

Then we came across a patch of wild strawberries, and that was the end of the hike.

Wild strawberry flowers are primary nectar source for “imperiled” Taylor’s checkerspot butterflies. The fruits are tiny, abundant, and delicious.



It was a tasty afternoon on the prairie.

For more information on Fender’s blue butterflies, other invertebrates, or invertebrate conservation, check out The Xerces Society.

{ 3 comments… read them below or add one }

Amy June 23, 2012 at 10:59 am

Wow!! What a beautiful blue butterfly!!! Thanks for the interesting post (as always)! :)


Rachel June 24, 2012 at 5:40 pm

Thanks for sharing your trip and the photos. We have endangered Karner’s blue butterflies in our area (New Hampshire) that also rely on lupine. I’ve never seen one, though – so it was really cool to see a Fender’s blue.


kerstin July 11, 2012 at 7:07 am

just came across your site via bigBANG studio’s link this morning. I’m devouring it! this post in particular, gave me so much hope in humanity… it’s so beautiful to see the way you’re living intentionally, raising your little ones, and loving the earth. thank you for the choices you make and the inspiration you provide via your blog! our big dreams include land, goats, chickens, gardens, and a timber frame construction of our own in the lovely countryside of Minnesota, sometime soon! for now, we’re in the city – living vicariously ;)


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