1993 Proceedings of the Midwest Oak Savanna Conferences
KARNER BLUE BUTTERFLY: DISTRIBUTION AND ABUNDANCE AT FORT MCCOY, WISCONSIN
Mark K. Leach
A two-year survey was conducted at Fort McCoy Military Reservation, Wisconsin for Karner blue butterflies and their larval-host plant, wild lupine. Within the 60,000 acre military training facility wild lupine was found in over 230 discrete areas occupying 2500 acres. Karner blues were found in 133 (72 percent) of the 186 lupine areas surveyed. These results suggest that Fort McCoy may play an important role in the recovery of this endangered species.
The Karner blue butterfly (Lycaeides melissa samuelis) was listed as a federally endangered species on December 14, 1992 (Fish and Wildlife Service 1992). Anticipating federal listing, in 1991 J. Kim Mellow (then Acting Chief of the Division of Natural Resource Management at Fort McCoy Military Reservation, U.S. Department of Defense) contracted with the Wisconsin Field Office of The Nature Conservancy to conduct a two-year survey for Karner blues and their larval-host plant, wild lupine (Lupinus perennis). Here, I summarize the results, which are presented in more depth in Leach (1993).
The Karner blue's life history is described in Givnish et al. (1988), Schweitzer (1989), Fish and Wildlife Service (1992), Bleser (1993), and Haack (IN PREP). It is a bivoltine insect, that is, it completes two generations each year, overwintering as eggs. Typically in Wisconsin, the spring-brood larvae hatch in mid-to-late April, feeding on wild lupine for about three to four weeks until pupation. Spring-brood adults emerge from late May to mid-June. Adults often mate, lay eggs, and die within a week of emergence. Summer-brood larvae grow for three or four weeks before pupating. The adults are flying and depositing eggs from mid-to-late July through mid-to-late August. Those eggs remain dormant until spring.
Wild lupine, a perennial member of the pea family (Fabaceae), grows most commonly on sandy soil, particularly in fire-prone landscapes. In Wisconsin it is most abundant in oak barrens (Curtis 1959). Wild lupine ranges from New England south along the coastal states and west across the southern Great Lakes Region to eastern Minnesota. The historic range of the Karner blue approximates the northern limit of wild lupine distribution, from eastern Minnesota to New Hampshire and Massachusetts.
Fort McCoy is a U.S. Army installation with a primary mission to train military personnel, both Active and Reserve. Fort McCoy is located in Monroe County in west central Wisconsin within the Driftless Region: an area of highly eroded hills characterized by narrow ridges and steep slopes often separated by broad valleys. The upland soils are generally thin with a large component of sand (Barndt and Langton NO DATE). The Fort occupies nearly 60,000 acres of which over 51,000 are managed for their natural resources; oak barrens and Jack-pine barrens comprise over 11,000 acres (Fort McCoy 1990).
Prior to this survey, the occurrence on Fort McCoy of lupine (Larsen 1990) and Karner blue butterflies (Swengel 1990) had been documented, but their distribution and abundance within the Fort had not. This survey was designed to determine the distribution and relative abundance of wild lupine and Karner blue butterflies on the Fort.
Approximately 20,000 acres of the uplands were visually inspected for wild lupine. Because of safety reasons, some large portions of the Fort were not surveyed.
Adult Karner blues were counted as survey crews walked once across a wild lupine area. Generally, surveyors walked parallel lines about 30 feet apart. Larger lupine sites were surveyed during each flight period, as were a subsample of smaller sites. Most sites were visited only once, during each of the four flight periods. Although many sites were surveyed, resulting in good information on the location of local populations, the number of adults counted is of limited value, because of day-to-day variability. Accurate counts of adults are difficult to obtain without intensive repeated sampling.
For each area we recorded a brief site description, weather conditions, the number of Karner blues, their sex (when known), and the names of plants from which Karner blues appeared to be obtaining nectar.
Based on survey results, I mapped over 230 wild lupine locations, totalling about 2500 acres. Most stands comprised less than 4.5 acres and contained fewer than 1000 lupine plants. Few stands were larger than 20 acres orwere estimated to contain more than 10,000 plants. The surveys were not exhaustive; more lupine areas are likely to be discovered. Most sites were in oak or Jack-pine barrens, oak woodlands (with canopy cover up to 80 percent), and woodland borders (often along the edges of roads or military trails). Lupines also grew in areas cleared for forestry, burned over areas (wild fires are common), and in the gaps and edges of pine plantations.
Karner blues were found in 133 (72 percent) of the 186 sites surveyed. The number of Karner blues tended to increase with site size and the number of lupines. Some large sites with few nectar plants contained abundant lupine but few Karners.
Adult Karner blues appeared to obtain nectar from various of the 41 native and alien plant species (Leach 1993). The most commonly observed were, for the spring brood: yellow sweet clover (Melilotus officinalis), dewberry (Rubus spp.), and the noxious leafy spurge (Euphorbia esula); summer brood: white sweet clover (Melilotus alba), leadplant (Amorpha canescens), and dotted mint (Monarda punctata).
This two-year survey of wild lupine and Karner blue butterflies documented the presence of both throughout much of Fort McCoy. The results led Bleser (1993) to describe the Fort as one of the best range-wide opportunities for habitat protection and metapopulation management. However, to insure the recovery of Karner blues at Fort McCoy, more information is needed for planning and implementation. To this end, the Natural Resource Management Division is continuing to survey and monitor wild lupine and Karners, and is developing a recovery and management plan in cooperation with the U.S. Fish and Wildlife Service Regional Office in Green Bay, Wisconsin. Major research projects are now underway, led by Judith Maxwell of the Department of Botany, U.W. Madison and Andy Bidwell of the School of Natural Resource, U.W. Stevens Point.
Information is needed on local population viability, metapopulation dynamics, habitat preferences and management, and the role of disturbance.
Barndt, W.D. and J.E. Langton. NO DATE. Soil survey of Monroe County, Wisconsin. U.S. Department of Agriculture, Soil Conservation Service.
Bleser, C.A. 1993. Status survey, management and monitoring activities for the Karner blue butterfly (Lycaeides melissa samuelis) in Wisconsin, 1990-1992. Final report submitted to the Office of Endangered Species, U.S. Fish and Wildlife Service. 88 pp. plus appendices.
Curtis, J.T. 1959. The Vegetation of Wisconsin. University of Wisconsin Press.
Fish and Wildlife Service. 1992. Endangered and threatened wildlife and plants; Determination of endangered statusfor the Karner blue butterfly. Federal Register (December 14, 1992) 57(240):59236-59244
Fort McCoy, Directorate of Engineering, Natural Resource Management Division. 1990. Fort McCoy Conservation Award Report. 64 pp.
Givnish, T.J., E.S. Menges, and D.F. Schweitzer. 1988. Minimum area requirements for long-term conservation of the Albany Pine Bush and Karner Blue Butterfly: an assessment. Report to the City of Albany from Malcom Pirnie, Inc., Albany, N.Y.
Haack, R.A. IN PREP. The endangered Karner blue butterfly (Lepidoptera: Lycaenidae): biology, management consideration, and data gaps. In Proceedings of the 9th Central Hardwood Forest Conference. USDA Forest Service, North Central Forest Experiment Station, General Technical Report.
Larsen, G. (compiler). 1990. Flora of Fort McCoy. Fort McCoy, Natural Resource Management Division. Unpublished. 18 pp.
Leach, M.K. 1993. Status and distribution of the Karner blue butterfly at Fort McCoy, Wisconsin: final report on a two-year survey. Report prepared for the Natural Resource Management Division, Fort McCoy Military Reservation, United States Army by The Nature Conservancy, Wisconsin Chapter.
Schweitzer, D.F. 1989. Fact sheet for the Karner blue butterfly with special reference to New York. Unpublished report, The Nature Conservancy.
Swengel, A.B. 1990. Karner blue survey reports to the WI DNR, Bureau of Endangered Resources.
Swengel, A. 1993. Observations on Karner larvae and lupine phenology. In, C.A. Bleser. Status survey, management and monitoring activities for the Karner blue butterfly (Lycaeides melissa samuelis) in Wisconsin, 1990-1992. Final report submitted to the Office of Endangered Species, U.S. Fish and Wildlife Service. Appendix 1.