Butterfly numbers declining due to climate change

Every year when summer temperatures sizzle and the rest of South Florida heads inside, a dedicated crew of citizen scientists ventures into the buggy heat to do an increasingly difficult job: count butterflies.

For the last quarter of a century, the North American Butterfly Association has tallied the nation’s population of butterflies three times a year, including the Fourth of July butterfly count now occurring in Florida. But across the nation, and particularly in Florida, finding butterflies to count is getting more difficult as habitats continue to vanish and climate change makes butterflies brief lives ever more perilous.

“Every single day there are fewer butterflies in the United States than there were the day before. You don’t have to be a genius to figure it out,” said geneticist Jeffrey Glassberg, NABA’s president and founder.

Nowhere is that more evident than among more specialized butterflies, like the many imperiled in South Florida, that live on an ecological razor’s edge balanced between their dependency on particular plants and fragmented populations. Of the 160 to 180 species found in the state, about two dozen are in trouble, among the highest concentration of threatened butterflies in the U.S. Now impacts from climate change — increased temperatures or sea rise that threaten host plants — may be driving them closer to the edge.

“Once upon a time I wasn’t happy unless we (counted) 50 species,” said wildlife biologist and butterfly expert Mark Salvato, who for the last 15 years has organized counts from Key West to Jacksonville. “Last year, I had 32.”

The counts are organized around 15-mile wide circles and are often conducted in the same locations — Key West, Key Largo, Homestead or Coral Gables — to provide consistency. Because of its warm weather, South Florida was always considered a mecca for rare butterflies.

The protection of butterflies has not always ended well in part because what drives them to extinction can sometimes be complicated. In 2014, the U.S. Fish and Wildlife Service added two butterflies, the Bartram’s hairstreak and Florida leafwing, to the endangered species list. The listing designated critical habitat, with rules for maintaining it. But critics have often said the designation does little in reality to protect the butterflies and their habitat on private land. After the University of Miami sold the last large tract of pine rockland — the butterflies only habitat — to a Palm Beach County developer, he quickly unveiled plans for a Walmart shopping center and nearly 1,000 apartments. The service is now finalizing a conservation plan that carves the 90-acre forest into two 20-plus acre preserves.

“The Schaus’ swallowtail has been listed for a long time and it’s no better off,” Glassberg said. “People have this misguided but understandable view that if someone takes a meadow and puts in a parking lot, that the butterflies just move somewhere else. But that’s not true. The butterflies are removed from the planet. You’ve just decreased the population of the world’s butterflies.”

Since he started counting butterflies in Florida, Salvato said both the number and diversity has declined. Because they react so quickly to changes, butterflies have been used to detect affects from climate change, which can occur faster than with mammals or birds. Warming temperatures prompted the furry brown three-spotted skipper, which looks more like a moth and feeds on grasses, to head north to Gainesville. A decade ago it was not seen outside Miami-Dade County, Salvato said. The Fulvous hairstreak, another brown butterfly that feeds on Brazilian pepper, is now showing up north of Melbourne.

The rarer butterflies found only in South Florida have not followed their lead in expanding, and sometimes not even occurring in historic ranges where they should be.

In the meantime, there’s the count, which is getting harder for its aging corps of volunteers.

“You may get ticks. You may get mosquito bit. People have to be pretty dedicated to stick with it,” said Linda Cooper, 76, who drives from Orlando every year to help run counts in Key Largo and Homestead.

Author: Going Green

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