• Start-up
  • Planning
  • Action
  • Evaluation

Regal fritillary habitat restoration and expansion are ongoing; managers are attempting to provide the "Old Field" habitat preferred by many native insects by removing invasive species and using manual cutting, mowing, herbicide, and prescribed fire to reduce the effects of ecological succession.

Managers at the Fort Indiantown Gap National Guard Training Center found that their objective of increasing habitat for the rare regal fritillary butterfly could potentially help populations persist under future climates, while providing more military training area.
A regal fritillary butterfly perched on a flower

Project Area

Map of Regal Fritillary areas at Fort Indiantown Gap National Guard Training Center
The Pennsylvania Army National Guard operates a training center in Fort Indiantown Gap, Pennsylvania, providing a professional training environment for soldiers, law enforcement officials and others. This 17,000 acre installation houses some rare and at-risk species, including the largest population of the regal fritillary butterfly in the eastern United States. Fort Indiantown Gap also contains the best example of native Pennsylvania warm-season grasses in the state, which support all stages of the regal fritillary’s life cycle. The installation has been actively managed to promote habitat for the fritillary and other butterfly species, and disturbances caused by military training have also played a role in maintaining that habitat.

Management Goals

2 regal frittilary butterflies on an orange flower

Natural resource managers at Fort Indiantown Gap are interested in providing a durable and safe training environment, while providing for the longevity of at-risk species in the area as the climate changes. This will include maintaining the oak and native warm-season grass vegetation community that provides habitat for the regal fritillary butterfly, and maintaining or increasing the density of plants that can provide nectar or act as larval hosts. In addition, they wish to support migratory and breeding monarch butterflies by increasing the presence of milkweeds. Approximately 200 acres are currently actively managed for the regal fritillary.

Climate Change Impacts

For this project, the most important anticipated climate change impacts include:
Longer growing season
Changes in phenology
Increased potential for wildfire
Increases in nonnative plant species

Challenges and Opportunities

Climate change will present challenges and opportunities for accomplishing the management objectives of this project, including:

Challenges

Longer growing seasons could produce mismatches in timing between the regal fritillary and preferred food plant species, such as the field violet (Viola sagittata).
Longer growing season could affect migration dates for the monarch and the availability of their food and host plants.
Increased risk of wildfire; fire can be a tool for sustaining butterfly habitat, but can be damaging if occurring during critical life stages.

Opportunities

Disturbances (fire, etc.) are generally good for promoting butterfly habitat.
Warm season grasses (butterfly habitat) may do well under future climates.
Creating new butterfly habitat also creates new areas that may be available for training.

Adaptation Actions

Project participants used the Adaptation Workbook to develop several adaptation actions for this project, including:

Area/Topic
Approach
Tactics
Warm season grasses/butterfly habitat
4.2. Prioritize and maintain sensitive or at-risk species or communities.
Maintain existing 200 acres of fritillary butterfly habitat through prescribed burns, mowing, mechanical removal of woody species, and planting desired native wildflowers.
Expand butterfly habitat area and training on 100 acres by removing hardwood species and restoring native warm season grasses (through spraying herbicide, mechanically removing woody species, and seeding native warm season grasses and wildflowers).
6.1. Manage habitats over a range of sites and conditions.
Maintain residual hardwoods in butterfly habitat area.
Assess alternative violet species that are acceptable host plants for the regal fritillary in the field (in addition to Viola sagittata). Multiple Viola species are used for captively reared regal caterpillars.
7.2. Maintain and create habitat corridors through reforestation or restoration.
Encourage and create corridors along roadways, right of ways, and any other openings between training areas that currently maintain regal fritillary populations by seeding/planting desired nectar species of wildflowers.
10.1 Promptly revegetate sites after disturbance.
Reseed after fire or other disturbances with preferred butterfly host/food species.

Monitoring

Project participants identified several monitoring items that could help inform future management, including:
Abundance and distribution of forb species in newly created habitat areas.
Presence/absence of fritillary butterflies (larval and adult stages).
Presence/absence of new violet species and whether or not caterpillars are using them.
Military use of new habitat areas for training purposes.

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Keywords

Wildlife habitat

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