Purdue University ecologist Patrick Zollner studied how people walking on nature trails can affect the reproduction habits of the Karner blue butterfly, which is a federally endangered species.

Resource managers are under increasing pressure to implement strategies that address the negative effects of outdoor recreational activities on wildlife. The study shows that human recreation can disrupt the breeding patterns of Karner blue butterflies, as well as other species.

Using a simulation model, the project found that significantly fewer eggs are laid by Karner blue butterfly females in sites at the Indiana Dunes National Park that are 10-15 meters from the trail. Plants that are farthest away have the most eggs. Zollner suggests that habitat patches be at least 25 meters from the trail.

“Depending on the circumstances, about 17 percent of the females are only laying half of their potential eggs because of human dis¬turbance,” Zollner said.

Zollner has studied how traffic affects Indiana wildlife and has submitted a proposal to study how the Huron-Manistee National Forest equestrian population impacts Karner blue butterflies.

This study is one of many funded as development of “seed” grants for researchers, either to begin start-up studies that may grow into larger work, or to complete ongoing projects.

This project and others are highlighted in our latest issue of our newsletter, The Helm. You can  also read the complete study (PDF).


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