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Rabbs’ fringe-limbed tree frog now presumed to be extinct

  • “Toughie,” the last known Rabbs’ fringe-limbed tree frog, was found dead in his enclosure by his keepers at the Atlanta Botanical Garden on September 26.
  • Environmental writer Andrew Revkin noted that Toughie’s death came “four years after the only other known member of this tropical species died at the Atlanta Zoo. Both were males, so the species was at its end well before they passed away.”
  • The natural range of Rabbs’ fringe-limbed tree frogs (Ecnomiohyla rabborum) was in the mountains of central Panama, where it would use its massive webbed hands and feet to glide from tree to tree in the cloud forest canopy it called home.

A rare tree frog species is believed to be extinct after the death of its last living member.

“Toughie,” the last-known Rabbs’ fringe-limbed tree frog, was found dead in his enclosure by his keepers at the Atlanta Botanical Garden on September 26. Environmental writer Andrew Revkin noted that Toughie’s death came “four years after the only other known member of this tropical species died at the Atlanta Zoo. Both were males, so the species was at its end well before they passed away.”

The natural range of Rabbs’ fringe-limbed tree frogs (Ecnomiohyla rabborum) was in the mountains of central Panama, where it would use its massive webbed hands and feet to glide from tree to tree in the cloud forest canopy it called home.

Most of the tropical frogs in the region were wiped out by a chytrid fungus epidemic that began in the 1990s. Five Rabbs’ fringe-limbed tree frogs were collected by conservationists in 2005 in the hopes of starting a captive breeding program, but those efforts ultimately proved unsuccessful — though the frogs did well enough in captivity, they never mated. The last female of the species died in 2009, also at the Atlanta Botanical Garden.

Toughie’s “advertising” call for potential mates was recorded for posterity in 2015:

The chytrid fungus Batrachochytrium dendrobatidis, often referred to as “Bd” by biologists, causes an infectious disease called chytridiomycosis that has been linked to declines in amphibian populations around the world. The Atlanta Botanical Garden, Southern Illinois University, and Zoo Atlanta sent a team of scientists to Panama to collect several live animals before the chytrid disease struck central Panama, and among the frogs they brought back to Atlanta was Ecnomiohyla rabborum, a previously unknown species.

First identified in 2005, Rabbs’ fringe-limbed tree frog was described to science in 2008 and named for conservationists George and Mary Rabb.

According to the International Union for the Conservation of Nature (IUCN), which first listed the species as Critically Endangered in 2009, Rabbs’ fringe-limbed tree frog became much less common after the chytrid fungus was detected in its range: “Calls are no longer heard at known localities, but in December 2007, one individual was heard in deep forest.”

It’s still possible there are undiscovered populations of Ecnomiohyla rabborum in Panama, but for now the species is presumed extinct.

The Atlanta Botanical Garden wrote on Facebook that Toughie “was the last documented member of a species relatively new to science. Found in Panama on an expedition to save animals from a deadly disease, our dear Rabbs’ frog was estimated to be about 12 years old. He will be missed by Garden staff and visitors alike.”

Rabb’s Fringe-limbed Treefrog (Ecnomiohyla rabborum). Photo by Brian Gratwicke / Wikimedia Commons.

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