Living With Bison

Karner Blue
Photo: FWS

The Sandhill Wildlife Area in central Wisconsin contains a small herd of American Bison in order to maintain the oak savanna ecosystem. It also contains protected populations of the endangered Karner Blue Butterfly. Its larval host is wild blue lupine. The butterfly is found in a few open areas such as oak savannas or barrens. Both the lupine and the Karner Blue are species of “disturbed” areas. Much of the habitat has been developed and has shrunk to a handful of areas in Great Lakes and northeastern US.

A team of scientists* studied the Sandhill Wildlife Area and butterfly species found in different habitats. They were especially interested in the habitat preferences of the Karner Blue. Female Karner Blues were most abundant in areas that contained bison wallows. This suggests that the disturbances caused by the bison are important to the Karner Blue and that loss of Bison has led to loss of disturbed areas and reduction of habitat. As a management strategy, it may be possible to enhance Karner Blue populations by creating artificial wallows.

In some areas, the oak savanna ecosystems are enhanced by controlled burns.  Management of areas with bison rather than fire could be an interesting experiment.

*Anna N. Hess, Robert J. Hess, Joy L. M. Hess, Beverly Paulan, Julie A. M. Hess. 2014. American bison influences on lepidopteran and wild blue lupine distribution in an oak savanna landscape. Journal of Insect Conservation. 18:327-338.