Nature’s notebook

North Carolina’s rarest butterfly needs special habitat

A St. Francis' satyr. Photo: Jenny McCarty

I wanted to know more about the rarest butterfly in North Carolina, so I caught up recently with Nick Haddad, the William Neal Reynolds Professor of Applied Ecology at N.C. State University to ask about the St. Francis’ satyr and its conservation status.

First, I wanted to know, what exactly is the St. Francis’ satyr, what does it look like and who discovered it?

Haddad said the St. Francis’ satyr is brown with a few thin, rusty-red strips and a row of small black spots. It is a small butterfly that lives in wetlands. It was discovered in 1983 by a young soldier, Thomas Parshall, training on a navigation course. Parshall was an amateur butterfly collector who recognized a different form of butterfly and soon described it as a new entity.

It is considered a sub-species. The other sub-species, Mitchell’s satyr, lives in Michigan, Mississippi, Alabama and Virginia. Its populations are small, and it is also endangered.

I asked Haddad about the butterfly’s behaviors. He said that more than any other butterfly he has observed (about 1,000 species and hundreds of thousands of individual butterflies), St. Francis’ satyr has one unique behavior: It likes to sit. Unlike other butterflies, it does not feed on flowers as an adult. Adults live an average three to four days.

The butterfly is federally endangered, and it is known only from Fort Bragg, the large Army installation in Cumberland and Hoke counties. Its populations appear stable inside the artillery ranges. Its populations outside Fort Bragg are smaller and mostly declining except where there have been restoration efforts.

Beaver disturbance and fire disturbance are necessary to create conditions suitable for them.

Research had told me they are found almost exclusively at Fort Bragg, that they utilize beaver swamps, and that too much or too little rainfall can make habitat unsuitable for them. Beaver disturbance and fire disturbance are necessary to create conditions suitable for them.

Haddad confirmed that what I read was true. St. Francis’ satyr lives in disturbed wetlands. Fort Bragg has three features not (or nearly not) found elsewhere: fire at natural rates of one- to three-year intervals, beaver populations that are mostly unimpeded, and few people in the natural habitats (and no people in artillery ranges).

What is it about those conditions or that habitat that they need? I have heard that some butterflies and moths are tied to a specific species of plant as their host. Is that true for the St. Francis’ satyr?

Haddad said some butterflies are tied to one plant, others can eat more than one. The host plant for St. Francis’ satyrs is a sedge; it is found in wetlands following disturbance. They live in abandoned beaver ponds. Those wetlands will become forests if not flooded or burned, and dense forest is bad for St. Francis’ satyr.

Haddad said other species that are in decline in the same habitats are largely plant species, such as endangered rough-leaved loosestrife, Venus flytraps and sandhills fire lily.

If fire disturbance and swamps are the key for this butterfly’s habitat, why are they not found on some of the N.C. Wildlife Resource Commission’s Sandhills Game Land also? Haddad said the answer isn’t known, and the game land is a target for future restoration and reintroduction. Until now, artillery has been key in replacing disturbances that were natural but stopped when humans arrived on the landscape.

Could they be somewhere else? How well have they been surveyed for?

Haddad said he doubts they are elsewhere, but that they are also in hard-to-find places. St. Francis’ satyr was first described in 1989. Populations of Mitchell’s satyr in Virginia, Alabama and Mississippi were found in about 2000. Although he said he would be shocked to learn of them elsewhere, there is some remote chance they could be. The greatest reason they’re unlikely to be found elsewhere is that while wetlands occur in other places, they aren’t likely to be extensive enough to sustain populations through the necessary disturbance. That’s a key characteristic of Fort Bragg, especially on the artillery ranges.

The rare St. Francis' satyr. Photo: Helen Haddad

How are they being studied, I asked Haddad. What type of research is taking place? There are many answers, he said, but most important, experiments are attempting to replicate disturbances by being like beavers: They create dams and remove trees. Those are the only areas where St. Francis’ satyr is now found outside the artillery ranges. I read also that they were being captive-reared, and Haddad confirmed that. He said those individuals are key, as they provide the seeds to restored populations.

Habitat loss is the biggest threat to the butterfly’s survival, he said, primarily through the loss of the disturbances (flooding or burning) needed.

What can conservationists or landowners do? For now, Haddad said, properly disturbing wetlands is key. That can happen through controlled burning that is allowed to burn through wetlands, and through maintaining beaver populations.

He concluded by saying that St. Francis’ satyr will not be found beyond Fort Bragg until two conditions are met: 1) Habitats are properly managed.  2) Individual butterflies raised on Fort Bragg are released in other places.

Possibilities are being explored with the Nature Conservancy and the Game Land, but any process will be a long one, with conservationists and scientists having to work with the U.S. Fish and Wildlife Service to establish the proper procedures and permissions.