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Dr. David J. Mladenoff
Department of Forest Ecology and Management
University of Wisconsin-Madison

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Contact  Sarah Pratt

Background:

The Karner blue butterfly (Kbb) is a federally listed endangered species that currently occurs in central and northwestern Wisconsin. Its range is restricted to those areas that support wild lupine, an obligate food source of Karner blue larvae.

The Wisconsin DNR coordinates the Karner blue butterfly Habitat Conservation Plan (HCP), which allows the nearly 40 partner agencies, companies, and organizations to continue operating in and around Karner blue habitat, provided they modify their activities to minimize incidental take (death, harm or harassment) of Karner blues.

Research question:

Can we produce a map that predicts the likelihood of Kbb occurrence, which will be used by the HCP partners to help them identify where they should focus their surveying efforts as they are planning land management activities that may affect Karner blue populations?

Approach:

We use a statistical technique called Logistic Regression to compare the landscape characteristics of known Karner blue occurrences to areas where Karner blues are absent. In some cases, we randomly generate the absence locations. These landscape characteristics include land and forest cover, soil type, climate, and topography.

An equation is generated from the statistical analysis that calculates the probability of Karner occurrence based on the landscape characteristics of any given point. This can then be applied to the entire study area to create a map of potential Karner blue butterfly habitat.

Results to date:

We have generated a draft map of Kbb probability for a study area in central Wisconsin. Currently we are working on expanding the map to cover the butterfly's entire range in the state.

Draft map produced of potential Karner blue butterfly habitat in central Wisconsin. The black dots represent known Karner occurrences. The colors represent increasing likelihood of Karner habitat from yellow to blue.