In 2012, there were only about four Schaus swallowtail butterflies left in their natural habitat of Southeast Florida and the Florida Keys.
Through conservation efforts, captive breeding and rearing at the University of Florida and subsequently reintroducing the butterflies into the wild, surveys conducted in 2015 and 2016 showed hundreds of naturally occurring Schaus swallowtails were alive and well in Elliott Key and Key Largo.
“The future for these butterflies currently looks brighter than it did six or seven years ago,” said Jaret Daniels of the University of Florida’s Museum of Natural History. “We’re pretty positive on the trajectory of where this butterfly is going.”
The program began in 2014 when University of Florida scientists produced 1,000 Schaus swallowtail larvae. More than 50 adult butterflies and 200 caterpillars were released into Elliott Key, which is part of Biscayne National Park.
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Pleased with the success of the original release, Daniels, in a collaborative program with the U.S. Fish and Wildlife Service and the Florida Department of Environmental Protection, plans several more throughout the Keys.
“The goal is to get them on to a few more islands,” he said this week.
Daniels was in Key Largo Monday releasing hundreds of Schaus swallowtail caterpillars in the woods of John Pennekamp Coral Reef State Park.
The team was expected to release about 100 Miami blue butterfly chrysalises in Long Key State Park Tuesday. Both species are only found in the Florida Keys and represent some of the most critically imperiled insects in North America, said Ken Warren, a Fish and Wildlife Service spokesman.
The Schaus swallowtail used to thrive in the tropical hardwood hammocks in the greater Miami area. But, because of habitat loss and population fragmentation over the years, the species is now found only in a few areas in Key Largo. It’s one of the rarest butterflies in the country and the only swallowtail listed as endangered with U.S. Fish and Wildlife.
Likewise, the Miami blue butterfly was once commonly found on the mainland, but is now found only in a few places in the Keys — mainly within the Key West and Great White Heron National Wildlife Refuges, Warren said. Like the Schaus swallowtail, the Miami blue is listed as endangered.
The Schaus swallowtails released at Pennekamp were placed mostly on branches of wild lime trees in the park. The voracious eaters devour about 6 to 8 inches of food a day, Daniels said.
“They’re essentially eating machines,” he said.
The scientists placed nets on some of the trees and left others exposed to see which larvae fair better against predators.
“We learn what works well and what doesn’t work well,” said Mark Salvato, a Fish and Wildlife Service biologist.
The Miami blue chrysalises are placed in a small piece of PVC pipe, about 2 inches long, with a metal screen the butterflies can crawl through when they emerge.
Kristin Rossetti, a research assistant at the Florida Museum of Natural History, said butterflies emerge from their chrysalises “within a week or two.”
The ones being released in Long Key State Park should all emerge by Friday, she said.
By contrast, the Schaus swallowtail can stay in their chrysalises anywhere from two months to two years, Rossetti said. They typically emerge during the rainy season. Sometimes, in captivity, scientists will spray the chrysalises with water to encourage the butterflies to emerge, Rossetti said.
The other major difference between the two butterflies is their size. The Miami blue is about the width of a thumbnail, while the Schaus swallowtail has a wingspan of about five inches.
Just as much as the Schaus swallowtails like to eat, they also like to mate, which is a good thing, since one of the main goals of the program is to make many butterflies. Male swallowtails have been known to wait beside chrysalises for females to emerge so they can get the process started and mate many times in their short life, which is about two weeks.
Likewise, the females are programmed with the goal of carrying on the population.
“Her biggest role is to lay as many eggs as possible,” Daniels said about the female Schaus swallowtail.
And, Daniels and his team are concerned with reproduction, because both Miami blues and Schaus swallowtails are susceptible to many factors, and it doesn’t take much to wipe out an entire population.
While expanded development certainly contributed greatly to both species’ decline, the team is more concerned about natural dangers that await the released larvae and chysalises, like rodents and other predators, as well as tropical storms, hurricanes and other forms of severe weather.
Out of the hundreds of Schaus swallowtail larvae released this week, less than 2 percent will become butterflies, Daniels said.
“They have a hard life ahead of them. They’re food for a lot of different organisms. That’s natural,” Daniels said. “What’s not natural is their population decline.”