January 19, 2011- By Nick Engelfried
Conservation groups concerned about the fate of declining invertebrates are asking the US Fish and Wildlife Service to provide emergency protections for one of the US insects most at risk of extinction. The Miami blue butterfly, a species found only in southern Florida, has declined during the last thirty years due to loss of habitat, pesticide use, and invasion of Florida’s ecosystems by non-native species accidentally introduced by people. The butterfly recently disappeared from one of the only sites where it was still known to cling to existence, prompting organizations like the Center for Biological Diversity to call for emergency measures to prevent its complete extinction.
“The Miami blue butterfly is in dire need of protection,” said Tierra Curry of the Center for Biological Diversity. “The Obama administration has to date shown no sense of urgency about saving the Miami blue butterfly or hundreds of other species waiting for protection.”
Expanding coastal development in Florida and the use of pesticides to control mosquitoes led to the decline of Miami blue populations in the early 1980s, and the butterfly was listed as a candidate for Endangered Species Act protection in 1984. However since that time a lack of funding for US Fish and Wildlife Service species protection programs has kept the Miami blue on the candidate list and prevented it receiving full protections. Meanwhile the butterflies have continued to shrink in numbers.
In addition to habitat destruction and poisoning by pesticides, Miami blues now face an additional threat: invasion of their habitat by iguanas. Though not native to Florida, iguanas have been introduced when pet owners have decided to turn them loose in a nearby swamp or park. The lizards thrive in Florida’s warm, moist climate but cause serious problems for local wildlife. Former pet iguanas threaten Miami blues when they feed on native plants like the yellow nicker, where the butterfly lays its eggs.
As if the species wasn’t already facing enough problems, Miami blues also have to contend with the hurricanes and tropical storms that regularly sweep through Florida ecosystems. Species that have already declined to very low levels can easily be wiped out of existence by a single unfortunate hurricane. Conservationists feared this had happened to the Miami blue in 1992, when Hurricane Andrew seemed to have extinguished the last known populations. Luckily the species was re-discovered in 1999 at Bahia Honda State Park, and since then has been found in the Key West National Wildlife Refuge (pictured above) as well. This latter population is now the only one known, as researchers reported in 2010 that the Miami blue seems to have disappeared from Bahia Honda Park.
Florida state law lists the Miami blue as endangered. However to truly save the species from extinction environmentalists say it needs protection from the federal government. Officially listing the butterfly under the Endangered Species Act would obligate the Fish and Wildlife Service to devote new resources to protecting the Miami blue’s habitat and addressing continued threats to its existence. “First and foremost, the known extant populations must be conserved,” says a statement from the Xerces Society for Invertebrate Conservation. “Their habitat should be managed to ensure adequate populations of larval host plants and adverse actions, such as mosquito control spraying, should be avoided.”
Miami blues in Key West are at least partly protected from further development, but are still potentially vulnerable to pesticides and other pollutants, and the introduction of exotic species. Meanwhile climate change will likely contribute to more intense tropical storms in their habitat, and rising sea levels could submerge low-lying islands in the Keys. All these dangers have triggered the renewed push to protect the Miami blue under federal law and secure a safer for this beautiful and unique butterfly of southern Florida.
Photo credit: US Fish and Wildlife Service