Community Characteristics and Vegetation Management of Karner Blue Butterfly (Lycaeides melissa samuelis) Habitats on Rights-of-Way in East- Central New York, USA

Abstract

Lupinus perennis L. (blue lupine) and associated nectar species represent critical habitat for the endangered, federally listed Lycaeides melissa samuelis Nabokov (Karner blue butterfly), and exist on transmission line rights-of-way in New York, USA. While rights-of-way provide habitat and may represent a potential corridor for butterfly dispersal among sites, few data are available to quantify habitat characteristics. We investigated rights-of-way in east-central New York to: characterize L. perennis populations and associated plant communities; quantify the relationship between L. perennis and both environmental characteristics and management schemes; and assess the relationship between butterfly population size and habitat characteristics. Lupinus perennis individuals were robust in communities with Comptonia peregrina, species in the Poaceae, and Daucus carota. Lupinus perennis and L. m. samuelis abundance were correlated positively with high relative light intensity and large patch areas, and inversely correlated with the number of years since the last management activity. There was no clear relationship between vegetation patterns and the different types of recent rights-of-way vegetation management schemes. To enhance L. perennis and L, m. samuelis populations, vegetation management on rights-of-way should reduce trees and shrubs, and increase light intensity to a level of photosynthetically active radiation that exceeds 65% of the maximum possible light intensity. Other manageable conditions associated with a larger index of L. m. samuelis population size include larger habitat areas and more frequent vegetation management that reduces the cover and density of woody species. The relationship between both L. perennis clump size and L. m. samuelis population size with the distance to the warm edge of the right-of-way suggests a potential influence of microclimate and merits further attention. Vegetation management based on infrequent mechanical removal of woody stems (e.g. handcutting, mowing, brush-hogging) was associated with increased woody plant density. A more frequent mechanical treatment or a seasonally timed application of an appropriate herbicide would be more effective at controlling the woody vegetation that competes with L. perennis.