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Black oak savanna with lupine in foreground
© Paul Labus |
Karner blue butterflies once were found from New England, west through the Great Lakes and into central Wisconsin and Minnesota. They occupied patches of oak savanna and pine barrens that supported lupine, the only known host plant for their caterpillars. In Indiana, they occurred in a narrow band along the shoreline of Lake Michigan.
Savannas and barrens are dynamic ecosystems that support a diverse assemblage of grasses and wildflowers along with scattered trees and shrubs. Wildfires played a critical role in shaping these natural communities. Prior to European settlement, periodic fires swept across the landscape, allowing herbaceous plants to flourish. In the absence of fire, woody species colonized areas and quickly shaded out grasses and wildflowers. Variations in fire frequency and intensity created an ever-changing mosaic of habitat patches in the landscape. Karner blue is one of several species of plants and animals that adapted to this dynamic, changing habitat.
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