National Parks: Biscayne and the Schaus Swallowtail

This guest post by Ryan Fessenden is part of a series covering Florida's national parks, inspired by the film National Parks Adventure currently showing on the MOSI IMAX Dome Theater.

Saving the Schaus
By Ryan Fessenden

Captive-bred Adult Schaus Swallowtail

Much attention is currently being paid to the decline of the migrating Monarch (Danaus plexippus) butterfly, and with good reason. Its population has seen a decline in the last two decades that is alarming. However, the Monarch is by no means the only threatened or endangered butterfly in the world or in Florida. The Schaus Swallowtail (Papilio aristodemus ponceanus) historically inhabited the rockland hammocks of southeast Florida and the upper Keys but now finds itself living almost entirely on one island in Biscayne National Park, seven miles off the coast of Florida City.

Left: Historic Range of Schaus Swallowtail; Right: Current Range

A Giant Swallowtail Relative
The Schaus Swallowtail is a larger swallowtail butterfly that is closely related to the far more common Giant Swallowtail (Papilio cresphontes) and is itself a subspecies of a butterfly that calls the Caribbean home, collectively known as the Island Swallowtail. Unlike all its cousins, however, the Schaus has one generation a year, from May to June, at the beginning of the wet season when its preferred host plant of Torchwood (Amyris elemifera) is producing new and tender leaves.

The Schaus Swallowtail is well adapted to its home in the hardwood hammocks of South Florida. In general it flies low at eye-level and has no trouble darting and weaving between trees. The Schaus also has the unusual ability to fly backwards for a short time, no doubt a way to avoid predators (and researchers) and the darker dorsal surface of the wings help it to blend into the broken light and shadow of the hammock.

Schaus Swallowtail Life Cycle

Like other similar swallowtail butterflies, this species has five larval stages, or instars, and the caterpillar looks very much like bird droppings. Overall it’s a bit more colorful that Giant Swallowtail larvae, with extra shades of yellow and a series of blue markings running down each side of the caterpillar. In addition, its osmeterium (that odd-smelling forked extension swallowtail larvae stick out when disturbed) is white. The pupa looks about the same as a Giant Swallowtail and it is in this stage that the butterfly stays until the following May when it emerges as an adult butterfly to mate and lay eggs.

Saving the Schaus Swallowtail
The University of Florida is now engaged in its second attempt to bring back this endangered butterfly. In the 1990s a team led by Dr. Thomas Emmel bred Schaus Swallowtails and released them to booster a shrinking population. Eventually things looked like they were stable, money ran out, and people went on to other things. In the meantime, for reasons not yet fully understood, the Schaus population again began to decline. When a survey team was sent to Elliot Key, the heart of Schaus Swallowtail territory in Biscayne National Park, a meager handful of the butterflies remained.

Larvae being reared on Wild Lime (Zanthoxylum fagara) in the Daniels Lab at the Florida Museum of Natural History, Gainesville FL.

The following year's goal went beyond observation and into capture with the goal of building a captive colony to release new adults on the island. These efforts were entirely successful as enough were brought back to start a healthy colony. At the time of this writing that colony is maintained at the University of Florida. The last two years have seen a relative explosion of the butterfly on Elliott Key, with each year seeing over 200 recorded sightings. It is the hope and goal of the team to save this beautiful butterfly from extinction, and perhaps help it to reclaim a foothold on the mainland of Florida.

Elliott Key and Biscayne National Park

Schaus Swallowtail habitat on Elliott Key
in Biscayne National Park

Each year a team of researchers go to Elliott Key and stay in one of two ranger homes built on the only developed portion of the island. The island itself is over seven miles long but usually no more than one hundred yards across. However, due to the thick hammock of hardwood trees dominated by Gumbo Limbo, Poisonwood, False Tameriad, Mahogany and of course Torchwood one cannot see one side of the island from the other.

The small developed area on the island features the houses, a welcome center and docks as well as a short boardwalk. The only other maintenance done on the island is keeping clear a narrow road cut down the middle of the island like a spine. This narrow road is all that is left of what would have been the town of Islandia before the island was bought by the federal government as part of the National Park. It is said that this narrow road was named Spite Highway by the developer of the island after it was bought. The name has stuck and any who transverses it would consider it an appropriate name given it is little more than broken up coral rock ad not easy on ones feet or tires. The road cuts through three salt marshes and is often flooded, making the two plus mile trek to the south side of the island where the butterfly is most prominent a challenge.

A researcher stands in a flooded portion of Spite Highway fully protected from mosquitoes.

The Schaus’ Swallowtail shares Elliot Key with a number of other lepidoptera, notably the Bahamian Swallowtail (Papilio andraemon), the Florida Purplewing (Eunica tatila), the Faithful Beauty (Composia fidelissima) and the Black Witch (Ascalapha odorata). Other animals include raccoons, turtles, snakes, tree snails, an introduced species of flying squirrel and, of course, mosquitoes - tons and tons of mosquitoes.

Butterflies are beautiful creatures and in many cases it doesn’t take much to seriously disrupt their life cycle. It is up to us to be aware of the world around us and to know just what kind of effect our very presence has on other life. The Schaus Swallowtail is very much unique among Florida’s butterflies and I don’t know about you, but I want to be able to show these amazing creatures to future generations not pinned in a box but flying by, dancing about the trees.

Ryan Fessenden is Assistant Manager of the Butterfly Rainforest at the University of Florida's Florida Museum of Natural History and is responsible for everything from USDA permitting to photography and identification. As a master’s student, Ryan focuses on sub-lethal effects of insecticides on Monarch larvae and has been a part of the Schaus Swallowtail conservation project for three years.