75 Protecting and Securing Our Nation without this human-made disturbance to their environment, this species could disappear. Land managers at Fort Indiantown Gap work closely with biologists at the US Fish & Wildlife Service and state agencies to manage the butterfly's habitat. They use GIS technology to record the butterfly population, plan ways to improve the habitat, and analyze how the butterfly responds to changes. Since 1992, the National Guard has actively managed the butterfly's habitat. They have set prescribed burns, mowed, seeded, and transplanted the violets the butterfly needs. Biologists have found that violet density increases four times when tanks trample the land and eight times after a prescribed burn. “Any environment on the East Coast always wants to be a deciduous forest, so any time there are open fields that don’t have some sort of disturbance to keep it open, it pretty much just turns into a forest,” said Mark Swartz, a wildlife biologist with the Conservation Division at Pennsylvania’s Department of Military and Veterans Affairs. “At the Gap, we see a lot of disturbance, from the military training and also our own land management.” A Delicate Species Flourishes in an Unlikely Place While the western subspecies can still be found in native grassland, the eastern regal fritillary butterfly, a large, bright-orange and black species with distinctive white markings, has been in continual decline as its natural habitat gradually disappears due to urban development and agricultural expansion. The eastern regal fritillary depends on three elements for survival: host plants for the caterpillars, nectar sources for the adult butterflies, and grass to use for shelter. The disturbances created by training activities and land management at Fort Indiantown Gap provide all three. The only plant that the butterfly’s larvae will eat, and therefore the only available host plant, is the violet. “Violets are a very disturbance-dependent species,” Swartz said. “They drop out when other plants start growing up nearby.” The butterfly's preferred nectar sources and habitat of open grass both require regular disturbances. “Warm-season grass is disturbance-dependent too,” he explains. “Grass is used by the butterflies for cover in all life stages.” In areas of the base that experience less disturbance, the environmental conditions required by the regal fritillary are maintained in other ways. “Fire is an important ecological management tool,” said Virginia Tilden, a biologist with the Conservation Division at Pennsylvania’s Department of Military and Veterans Affairs. “We use prescribed fires to clear out taller grass growth and prevent forest fires in the area, but it also helps maintain the open spaces of native vegetation, and that’s why the butterfly is here.” Tracking and Mapping of Habitats “When I first started working on this project in 2002, we were still using paper maps,” Swartz said. “We would look at the maps, pick out an area and then go look and see what was there.” By 2010, Fort Indiantown Gap staff started to use GIS to map the butterfly's habitat. They created map layers with data about the environment to track and analyze the area’s fragile conditions. The isolation of the subspecies leaves it vulnerable. In recent years, the fort has partnered with the Pennsylvania Game Commission, the US Fish & Wildlife Service, ZooAmerica, Temple University, Pennsylvania Western University, and Penn State Dubois to establish new sites in the state where the species can thrive. To track the current butterfly population and environmental conditions and aid in developing new places where the species can thrive, Fort Indiantown Gap staff developed a GIS-powered workflow. “We started using ArcGIS Survey123 to create public apps for the students who will be helping us at the reintroduction sites,” Tilden said.
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