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With 17,000 acres under its purview, Fort Indiantown Gap is host to more than loud booms and military personnel. It’s not just the sheer volume of space that makes the sprawling acreage at the northern end of Lebanon County a fecund foster of large swaths of the biosphere. In fact, the booms themselves play a large role.

The regal fritillary butterfly once fluttered abundantly up and down the East Coast. Unlike its visually similar cousin, the monarch – regals are said to look like a “monarch dipped in chocolate” – the regal fritillary butterfly does not migrate and instead will live out its days on grasslands, each summer a lifetime for a new generation.

Between population growth, increased farming, and the advent of modern lawnscaping, there’s just not much grassland left today for these lepidoptera. Today, Fort Indiantown Gap is alone in the northeast for having a population of regals that patrol its grounds.

The ecology of Fort Indiantown Gap is particularly situated for the regal due to the frequent soil disturbance and patchy fires that come along with being a bombardment zone for your friendly neighborhood A-10 dropping ordnance during training exercises. These disturbances create conditions for grassland particularly suited to the regal, where three main habitat components conspire to provide the perfect patch for regals to flourish:

  • Larval host plants, like arrow-leaf violet
  • Adult nectar sources, like milkweed and thistle
  • Bunch grasses, like little bluestem and broomsedge

In the mid-1990s, biologists at Fort Indiantown Gap took steps to make sure the regals know they – unlike you – are welcome to wander the base grounds and make themselves at home. In addition to helping propagate the plants regals depend on, and removing the woody vegetation that can interfere with the growth of the desired vegetation, biologists have also run a captive rearing program for the regal fritillary in partnership with ZooAmerica. Females are caught at the base and taken to ZooAmerica for egg laying, with yield of the thousands of eggs one female lays now reaching upwards of 60% through innovations in the incubation process.

  • A regal fritillary butterfly on the grounds of Fort Indiantown Gap. (Photo provided by Maddie Ferner)
  • A regal fritillary butterfly on the grounds of Fort Indiantown Gap. (Photo provided by Maddie Ferner)
  • A regal fritillary butterfly on the grounds of Fort Indiantown Gap. (Photo provided by Maddie Ferner)
  • Two regal fritillary butterflies on the grounds of Fort Indiantown Gap. (Photo provided by Maddie Ferner)
  • A regal fritillary butterfly on the grounds of Fort Indiantown Gap. (Photo provided by Maddie Ferner)
  • A regal fritillary butterfly on the grounds of Fort Indiantown Gap. (Photo provided by Maddie Ferner)

All of this knowledge and more was shared on the annual habitat tours offered by Fort Indiantown Gap, with the last of this year’s tours taking place on Saturday, July 9. While you now have to wait some time for the next round of tour slots to be offered – organizers typically announce details in June – you can get a peek of the tour experience through LebTown’s eyes.

The tour begins with a caravan into the training grounds, led by staff from the Pennsylvania Department of Military and Veterans Affairs. Each tour goer was required to fill out registration paperwork through the iSportsman website.

Although the registration process was a bit cumbersome, everything went smoothly once on-site. The registration process is part of a shift of the tours to be a more personal, hands-on experience for participants.

This year, about 200 people went on tours, which filled up quickly. Organizers said they might add an extra tour day next year. This year, tours were offered on Friday, July 1; Saturday, July 2; Sunday, July 3; Friday, July 8; Saturday, July 9; and Sunday, July 10. In addition to this being a prime time of year to see the regal, the base also tends to be quieter around the Fourth of July holiday.

The tour of the regal fritillary butterfly habitat at Fort Indiantown Gap began with a caravan into the training grounds.

Once at the site, the tour assembled to trek down a mowed path into the habitat. Although the habitat is directly adjacent to a large ordinance training site, the habitat itself is not used for exercises – but that doesn’t mean you don’t need to use caution if you head off the beaten path.

Tour goers assemble at the beginning of the trek into the regal fritillary butterfly habitat at Fort Indiantown Gap. Smaller groups on this year’s tours provided more one-on-one time between DMVA staff and the public, to answer questions and point out interesting aspects of the habitat.
Although the habitat itself is not used for exercises, it is directly adjacent to fields used for live-fire exercises. These grounds are only accessible by the public during the annual tours.

Read More: Fort Indiantown Gap to offer free tours of regal fritillary butterfly habitat

The first thing that stands out about the habitat is the abundance of natural grasslands.

“We put a lot of hours in not only trying to conserve the butterflies but the grassland species,” said the DMVA’s Erika McKinney, an expert in regal rearing and butterflies. McKinney said the tours are an opportunity to show the public the intensive and long-running work that has gone into supporting the regal fritillary butterfly on base grounds.

Regal rearing & butterflies expert Erika McKinney educates tour goers on the larval hosts and nectar sources of the regal fritillary butterfly, which today only exists north of Mississippi in a protected habitat on the base of Fort Indiantown Gap. Behind McKinney stands regals & insects expert Maddie Ferner.

The perpetual grasslands at Fort Indiantown Gap are abundant with all types of nectar sources, some of which bloom earlier in the season and others – like the field thistle – which provide important late season nectar sources to the regal.

The perpetual grasslands at Fort Indiantown Gap end up being particularly suited to the vegetation associated with the regal fritillary butterfly because of patch fires (both intentional burns and side effects of training exercises) which help to clear out woody vegetation that can impede the growth of larval hosts and nectar sources.

Maddie Ferner demonstrates expert ability to hold the regal fritillary in a way that does not damage them. On the left, a male regal can be seen – identifiable by the white and orange spots on hindwing. On the right, a female regal with two rows of white spots on hindwing. Males also emerge earlier in the year than females, hence the more muted tones you see here.

The tour in total lasted a couple hours, including travel to and from the habitat site.

The habitat is home to a number of critters, including this smooth green snake. (Photo provided by Maddie Ferner)

For more information about the habitat and the partnership with ZooAmerica, visit the DMVA’s website.

To receive information on future tours, email RA-DMVA-Wildlife@pa.gov to be added to the department’s mailing list, or follow Fort Indiantown Gap on Facebook.

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