Saint Francis' Satyr Butterfly

Neonympha mitchellii francisci

Description

Saint Francis' satyr is a fairly small, dark brown butterfly with a wingspan of 1.3-1.7 in (33-44 mm). Saint Francis' satyr and Mitchell's satyr (Neonympha mitchellii mitchellii ), the northern subspecies, which was classified as endangered on May 20, 1992, are nearly identical in size and show only a slight degree of sexual size dimorphism. Like most species in the wood nymph group, Saint Francis' satyr has conspicuous "eyespots" on the lower surfaces of the wings. These eyespots are dark maroon brown in the center, reflecting a silver cast in certain lights. The border of these dark eyespots is straw yellow in color, with an outermost border of dark brown. The eyespots are usually round to slightly oval and are well-developed on the fore wings as well as on the hind wing. The spots are accented by two bright orange bands along the posterior wing edges and two darker brown bands across the central portion of each wing. Saint Francis' satyr, like its subspecies, can be distinguished from its North American congener, N. areolata, by the latter's well-marked eye-spots on the upper wing surfaces and brighter orange bands on the hind wing, as well as by its lighter coloration and stronger flight.

Behavior

The annual life cycle of Saint Francis' satyr, unlike Mitchell's satyr, is bivoltine, having two adult flights or generations per year. Larval host plants are believed to be graminoids associated with grasses, sedges, and rushes. Little else is known about the life history of this butterfly.

Habitat

The habitat occupied by this satyr consists primarily of wide, wet meadows dominated by sedges and other wetland graminoids. In North Carolina sandhills, such meadows are often relicts of beaver activity. Unlike the habitat of Mitchell's satyr, the North Carolina species' habitat cannot be properly called a fen because the waters of this sandhills region are extremely poor in organic nutrients. The boggy areas of the sandhills are quite acidic as well as ephemeral, succeeding either to procosin or swamp forest if not kept open by frequent beaver activity. Under the natural regime of frequent forest fires ignited by summer thunderstorms, the sandhills were once covered with a much more open type of woodland, dominated by longleaf pine, wiregrass, and other fire-tolerant species. The type of forest that currently exists along the creek inhabited by Saint Francis' satyr can grow up only under a long period of fire suppression. The dominance on this site of loblolly pine is due primarily to past forestry management practices and not any form of natural succession.

Distribution

Saint Francis' satyr is extremely restricted geographically, and Mitchell's satyr has been eliminated from approximately half of its range in North Carolina. Extensive searches have been made of suitable habitat in North Carolina and South Carolina, but no other populations have been found. The current narrow distribution could be the result of the enormous environmental changes that have occurred in the southern coastal plains within the last 100 years. Only the discovery of additional populations or fossil remains can clarify this situation. Steve Hall (1993) states that "in order for francisci to have survived over the past 10,000 years, there must surely have been more populations and greater numbers of individuals than apparently now exist." Reductions in francisci 's range would have accompanied the extensive loss of wetland habitats in the coastal plain.

Saint Francis's satyr is now known to exist in only a single population fragmented into less than six small colonies that occupy a total area no larger than a few square miles. In 1989 Parshall and Kral estimated that the single known population produced less than 100 individuals a year, but by 1991 the species appeared to be extinct.

Threats

The enormous changes in the southern coastal plain during the past 100 years have severely altered the butterfly's habitat. The boggy areas of the sand-hills are quite acidic as well as ephemeral, succeeding either to procosin or swamp forest if not kept open by frequent beaver activity. Beavers had been virtually eliminated from North Carolina by the turn of the century, and although beaver reintroduction began in 1939, it took several decades before they again became an agent for creation of the sage meadow habitats favored by Saint Francis' satyr.

In Steve Hall's 1993 study, he states that "as the landscape mosaic of open woodlands and wetlands of the coastal plain declined through the past two centuries, the range of francisci must have become increasingly fragmented. Although the isolated populations may have persisted as long as suitable habitat remained, the structure of their meta populations would have been destroyed" and they would have had less access to new habitats because the absence of forest fires would have allowed the forest to become denser.

Saint Francis' satyr is highly prized by collectors, including commercial collectors who often systematically collect every individual available. Several populations are known to have been obliterated by collectors, and others are known to be extremely vulnerable to this threat. The single known population was so hard hit by collectors in the three years following its initial discovery that it was believed to have been collected to extinction. Collectors reportedly visited the known site every day throughout the flight periods, taking every adult they saw. North Carolina law does not protect insects from collection, and the Department of Defense has no regulations restricting collection of military land.

Because the range and numbers of Saint Francis' satyr are so small, the species is threatened by catastrophic climatic events, inbreeding, disease and parasitism. Part of the occupied area is adjacent to regularly traveled roads, where there is the threat of toxic spills onto the species' wetland habitat.

Other potential threats include pest control programs for mosquitoes and gypsy moths, and beaver control.

Conservation and Recovery

Current military use of the species' habitat is favorable; the frequent fires caused by shelling are undoubtedly a reason why the species survives on military lands and not on surrounding private lands. Department of Defense personnel are aware of the species' plight and have been cooperative in protection efforts. Troop movements have been directed away from areas where the satyr occurs.

The U.S. Fish and Wildlife Service determined that to designate critical habitat would further expose the butterfly to collectors. Because the current habitat is on military land, no further protection is needed beyond that stipulated by the Endangered Species Act.

Contacts

U.S. Fish and Wildlife Service
Regional Office of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Telephone: (404) 679-4159
Fax: (404) 679-1111
http://southeast.fws.gov
Asheville Ecological Services Field Office
160 Zillicoa St.
Asheville, North Carolina 28801-1082
Telephone: (828) 258-3939
Fax: (828) 258-5330

References

U.S. Fish and Wildlife Service. 18 April 1994. "Emergency Rule to List the Saint Francis Satyr as Endangered." Federal Register 59(74): 18324-18327.

U. S. Fish and Wildlife Service. 26 January 1995. "Saint Francis' Satyr and Hine's Emerald Dragonfly; Final Rules." Federal Register 60(17): 5263-5267.