The Role of Disturbance in Habitat Restoration and Management for the Eastern Regal Fritillary (Speyeria idalia idalia) at a Military Installation in Pennsylvania

Abstract

We observed and manipulated habitat for a remnant population of the eastern regal fritillary (Speyeria idalia idalia), at Fort Indiantown Gap, an Army National Guard installation in Pennsylvania. Three years of study indicate that the key elements of regal fritillary habitat (larval host plants, adult nectar sources, and adult resting sites) depend on severe disturbance to soils and vegetation. Army training activity (military tracked vehicles and fire) maintained populations of larval host plants (violets) more effectively than combinations of light soil scarification, mowing, and removal of mowed biomass. In addition, plantings of nectar species (milkweeds and thistles) grew best on wetter sites after applying a non-selective herbicide (glyphosate), although herbiciding may be unnecessary on uplands. Because the required larval food and adult nectar and resting sites persist only with recurring disturbance, a practical, biologically effective, and essentially permanent program of disturbance is needed to sustain the population at Fort Indiantown Gap.