Butterflies feeding on carrion

Description:

I saw a lot of these Coronis fritillarys that day. These were feeding on carrion (rotting corpse) in the road. Unfortunately butterflies do not receive enough sodium and other minerals from flowers alone. I've only read about this behavior so this is the first time I've actually witnessed it.

Habitat:

Spotted on a gravel road near the Umtanum creek in the Cascade foothills. Pine trees and shrubs along the creek and valleys, while the hills are sagebrush steppe. Above 2000 ft el.