Behavior as a tool for assessing a managed landscape: a case study of the Karner blue butterfly
2009
Pickens, Bradley A. | Root, Karen V.
In an increasingly human-dominated landscape, effective management of disturbance-maintained ecosystems, such as grasslands and savannas, is critical to the conservation of biodiversity. Yet, the response of individual organisms to landscapes created by disturbances and management is rarely studied. In this study, we examined the endangered Karner blue butterfly, Lycaeides melissa samuelis, in a heterogeneous oak savanna. Our objective was to quantify the butterfly's habitat use and behavior to assess the effects of prescribed burning. The oak savanna management in Ohio, USA divides each Karner blue site (n = 4) into three units. Each one-third unit is then burned, mowed, or unmanaged in an annual rotation within each site, and the result is a fire return interval of ~3 years. Our surveys measured habitat use, while behavior observations quantified reproduction and foraging for the two annual broods. Our habitat use results showed burned treatments were recolonized quickly, but there was not a clear selection for burned treatments. Foraging rates were similar in all treatments; however, females oviposited significantly less in unmanaged treatments (only 5 of 127 ovipositions). This oviposition preference was likely due to habitat degradation and the availability of recently burned, early successional habitat. Since Karner blues avoided reproduction in units unburned for >=4 years, these units could be burned to create high quality early successional habitat. These results demonstrate how behavioral decisions can be pivotal forces driving spatial population dynamics. Our case study demonstrates how a fine-scale landscape perspective combined with measurements of behavioral processes can assist with management decision-making.
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