Karner Blue - Management Considerations

Management Considerations

According to reviews, habitat loss through direct conversion to other land uses and through succession are considered the major causes of the decline of the Karner blue butterfly. At the time of this writing (2006), two reviews summarize the recent status of Karner blue butterfly across its range. Recovery criteria are addressed by, while Christenson and Lentz discuss lessons learned developing a statewide Habitat Conservation Plan for Wisconsin.

Articles that address Karner blue butterfly sampling methodology include. Swengel found that surveys for Karner blue butterfly adults appeared more efficient than those for larvae. Evidence of different catchability and/or detectability of male and female Karner blue butterflies led King to suggest calculating male and female population sizes separately. General descriptions of Karner blue butterfly rearing methods and translocation/ reintroduction techniques are available.

A wide variety of management techniques can be compatible with maintaining Karner blue butterfly populations when attention is paid to implementing them at appropriate times and at intensities, scales, and frequencies that Karner blue butterflies can tolerate. For example, mowing can maintain open areas with little to no detrimental effect on Karner blue butterflies on sites where burning is impractical or in areas too small to support populations of Karner blue butterflies likely to survive a burn. On restored oak savanna sites in south-central Wisconsin, no significant (p=0.924) differences were detected between Karner blue butterfly densities on sites burned in summer, sites mowed in August, and control sites. Mowing with a blade height >4 inches (10 cm) should be performed annually or biennially in the fall or winter and clippings should be left in place. Effects of mowing, burning, and other management techniques and land uses on the average number of Karner blue butterflies observed per survey hour are included in. Recommendations on the use of a wide range of management techniques such as thinning, rotational grazing, and planting of wild lupine and/or nectar species can be found in.

According to reviews and general field observations, management activities that are typically harmful to Karner blue butterflies include management that increases deer and/or grouse populations, close-cropped grazing, frequent or poorly-timed mowing, plowing, use of herbicides that kill lupine or nectar plants, and use of pesticides that are detrimental to Karner blue butterflies, ants they associate with, or pollinators of species they use for nectar. Information on the impacts of an insecticide on Karner blue butterflies and some herbicides on Karner blue butterflies as well as lupine and nectar species are available. According to the Karner blue butterfly recovery plan, management activities that can have a detrimental effect should be timed to allow at least 2 generations between repeat treatments and, if possible, critical subpopulations should be divided into discrete management units.