|Practical guide to St. Francis satyr
St. Francis saytr live in a dynamic landscape, and at any currently occupied wetland site habitat change will cause the butterfly's population to decline. Any given wetland becomes unsuitable for one of two reasons: either it succeeds to riparian habitat that does not support the caterpillars food plants, or disturbance sets back succession allowing the butterflies food plants to persist longer. The disturbance may come in one of two forms. Perhaps the most important disturbance maintaining St. Francis satyr habitats is wetland formation by beavers. Beavers flood an area and remove standing hardwoods. After beavers leave a site (either by choice or because they are removed by predators or humans), wetland succession leads to the creation of wetlands that include food plants for St. Francis satyrs. As vegetative succession proceeds, these same plants are lost, shaded out by taller shrubs and trees, or excluded as sites dry. Every site that we have observed is on an abandoned beaver dam, though there are some sites inside artillery impact areas at Ft. Bragg that appear to be maintained primarily by fire. On dry years when burns are hot, they can penetrated wetlands created by beaver activities, and this may also help to prolong the length of time a site is suitable.Without beaver, wetlands become unsuitable for St. Francis satyr within decades. Understanding how beaver dynamics affect habitat dynamics is critical for restoration and recovery of this butterfly, and this is one of the issues motivating graduate student Becky Bartel's dissertation.
St. Francis satyr habitats are characterized by wetland grasses and sedges, mucky soils that are usually saturated with water (and often with surface flow of water just below the vegetation), and some shrubs or trees providing shade. Sites that are too open often do not support St. Francis satyr (but do support the closely related Helicta and Georgia satyrs).
Some of the key plants in St. Francis satyr habitats include their likely caterpillar food plant, Carex mitchelliana. Although we have never seen the caterpillar in the wild, we have had some success rearing it in the lab on C. mitchelliana, and it is a dominant sedge in the areas where St. Francis satyr occurs. Sedges are a likely hostplant based on feeding habits of other Neonympha. There are a number of other sedges that are conspiciuous in St. Francis satyr sites, including C. atlantica, C. glaucensens, C. lurida, C. lonchocarpa, and, at some sites, C. turgensens. Some other sedges that occur less regularly in our sites include Carex stricta (the likely host plant of Neonympha mitchelliana), C. debilis, and C. mulenberghii. One plant species that is associated with Helicta satyr sites, but not St. Francis satyr sites is Calamovilfa sp.
The persistence of beaver meadows is attributed to high light penetration and elevated moisture and nitrogen levels. In addition to the Carex, some other common plants in St. Francis satyr sites include red maple, alder, giant cane. Common shrubs such as fetterbush, inkberry, sweet pepperbush, Virginia sweetspire, and highbush blueberry are also prevalent in these areas.