Schaus Swallowtail Butterfly

Heraclides aristodemus ponceanus

Description

Also known as the Keys swallowtail butterfly, Schaus swallowtail, Heraclides aristodemus ponceanus, is a large (4-5 in or 10-13 cm), dark brown butterfly with dull yellow markings. Its dark tail is bordered in yellow. The black antennae have yellow knobs and black tips. It is easily confused with the giant swallowtail (H. cresphontes cramer ), which is found in portions of the same habitat. The giant swallowtail is larger than the Schaus and has deeper coloration—bright yellow on coal black.

The Schaus swallowtail is considered one of five subspecies of H. aristodemus, a species endemic to the Antilles that tends to vary in appearance according to geographical region. Some taxonomists believe that the Schaus swallowtail is a distinct species. It has also been scientifically classified as Papilio aristodemus ponceanus or P. ponceana.

Behavior

The Schaus swallowtail emerges from its chrysalis in May and June and feeds on the nectar of guava, cheese shrub, and wild coffee blossoms. It perches on the torchwood plant to bask in the sun. The male is territorial and patrols by circling slowly around intruding males. Schaus swallowtails do not migrate as a group, although individuals sometimes fly across the open water between islands. Adults live about two weeks.

During courtship, the male hovers above and behind the female, who is positioned on the ground with flattened, vibrating wings and a raised abdomen. After fertilization, the female deposits single eggs on the leaves of torchwood and wild lime, the larval host plants. The larvae hatch after three to five days and go through four successive molts. The caterpillar feeds on tender, new growth. After about 20 days, the caterpillar attaches itself to a branch and weaves a thick chrysalis, which can remain dormant for one or two years before the adult butterfly emerges.

Habitat

The Schaus swallowtail lives on hardwood hammocks, which are areas of mature hardwood forest with deep, humus-rich soil typically found in sub-tropical regions of the southern United States.

Distribution

In the past, this swallowtail was found in Florida from the South Miami area (Dade County) to the Lower Matecumbe Key (Monroe County). The last known mainland specimen was collected at Coconut Grove in 1924.

The Schaus swallowtail now occurs only in the Florida Keys (Monroe County) and is most numerous where host plants are abundant. The population at Elliot Key in 1986 was estimated at between 750 and 1,000, with smaller colonies inhabiting several neighboring islands.

Although Hurricane Andrew devastated the butterfly's stronghold, Biscayne National Park, in 1992, the population increased two years later to more than 600 individuals. In the 1990s, major releases of captive-bred butterflies have greatly increased the recovery potential for the species. In April 1995, researchers released 760 captive-bred pupae at six publicly owned sites on Key Largo and one site in Miami, Florida. The purpose of these releases was to supplement the sparse numbers of individuals remaining on Key Largo and to reestablish the sub-species in the Miami area, where it was originally described. In a cooperative effort between the U. S. Fish and Wildlife Service (FWS) and the University of Florida at Gainesville, more than 250 Schaus swallowtail butterflies were released May 13, 1996 on the 400-acre (162-hectare) Deering Estate at Cutler, south of Miami. Another 550 butterflies were released at the same location a month later.

Threats

With the urbanization of south Florida, the Schaus swallowtail lost much of its original habitat and suffered the effects of pesticide use. During the 1970s it was found only in Key Biscayne National Park and on north Key Largo. It was declared Threatened in 1976 but because of a decline in numbers was reclassified as Endangered in 1984.

Conservation and Recovery

The Florida Park Service and the FWS now protect much of northern Key Largo. Under the FWS Coastal Ecosystem Restoration program, state and federal biologists are planting hardwood hammock species to reconnect fragmented habitats for the butterfly and other listed species endemic to Key Largo. Aerial application of mosquito insecticide, which could harm the Schaus swallowtail, has been discontinued over these conservation lands in the last few years. Additionally, an agreement was reached with the Monroe County Mosquito Control District in early 1995 to discontinue ground spraying of mosquito insecticide in important Schaus swallowtail habitat during the butterfly's breeding season. In another significant action, the Florida Keys Electric Cooperative has agreed to enhance and preserve tropical hardwood hammocks important to Schaus swallowtail recovery within a 15-mi (24-km) powerline easement on Key Largo.

With habitat protection in place, the focus of the recovery effort has shifted to the butterfly itself, with the highly successful Schaus swallowtail captive breeding program, which became very successful. The FWS recovery team recommended reestablishing colonies elsewhere within the historic range; in an attempt to achieve this goal, 800 swallowtails were released in 1996 at the Deering Estate south of Miami, a property owned by the State of Florida and Dade County, which includes the largest original tropical hardwood hammock and pine rockland ecosystem in the mainland United States.

The outlook is encouraging for the survival of the Schaus swallowtail on Key Largo and the islands that make up the Biscayne National Park. Habitats within the park are well-managed, and larval host plants are abundant. Successful control of pesticide spraying within the swallowtail's range has reduced one of its greatest immediate threats. Since 1980 the FWS has been acquiring lands on north Key Largo for the Crocodile Lake National Wildlife Refuge— an area within the historic range of the butterfly. These land acquisitions, combined with the recent species reintroduction efforts, may afford the swallowtail an opportunity to increase its numbers in an expanded habitat.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

References

Brown, C. H. 1976. "A Colony of Papilio aristodemus ponceanus in the Upper Florida Keys." Journal of the Georgia Entomological Society 11:117-118.

Covell, C. V. 1976. "The Schaus Swallowtail: Threatened Species." Insect World Digest 3:21-26.

General Accounting Office. 1988. "EndangeredSpecies: Management Improvements Could Enhance Recovery Program." General Accounting Office, Washington, D.C.

U.S. Fish and Wildlife Service. 1982. "Schaus Swallowtail Butterfly Recovery Plan." U.S. Fish and Wildlife Service.