Habitat assessment of nectar resources is important for butterfly conservation planning. Studies show butterflies with rich sugar and amino acid diets often experience improved fecundity, longevity, and increased fitness over a lifetime. Although the Karner blue, a bivoltine butterfly listed as federally endangered since 1992, was reintroduced to Ohio there has been varying reintroduction success. The aim of this study is to couple existing nectar plant density data with nectar quality characteristics and floral abundance data for 24 oak savanna forbs in Karner blue butterfly habitats in Ohio and Michigan to develop site-specific nectar resource availability during each flight period. We tested the hypothesis that nectar quality would be important to predicting where Karner blue butterflies were present or absent over time. Inflorescences from target species were centrifuged to remove nectar and determine volume, sugar and amino acid concentrations. For each adult flight period, species nectar content measures were combined with flowering stem density estimates to determine site-specific nectar quality landscapes.
Results/Conclusions
Oak savanna forbs sampled had an average nectar volume of 0.03-2.9 µL per flower. Nectar composition ranged between 4.9-61.3 g of sugar per mL and 14.0-178.0 ng of amino acids per µL. A preliminary analysis for a seven species subset of the target species for Ohio sites did not reveal any initial correlation between Karner blue butterfly occupancy status and nectar quality availability. These data may be useful for land managers developing habitat assessments and restorations for butterfly conservation. Ongoing nectar quality analyses and further sampling are needed to thoroughly evaluate the importance of nutrient rich nectar resources for the Karner blue and other oak savanna butterflies.