There are 17 known spots designated by the U.S. Fish and Wildlife Service as critical habitat for the rock frog, all of them on private land. Longo and Lopez, working for a research and public education initiative called Proyecto Coqui, have been trying to determine the health of the populations on those isolated patches.
"That's why it's such a vulnerable species," Lopez said. "If something happens to the habitat, people can't just grab them and put them in another place on the island because this habitat is only found on the southeast of the island."
In densely populated Haiti, the degradation of the environment has been so severe that only a handful of species are known for certain to still be viable in the country and even they are in trouble, said S. Blair Hedges, a biology professor at Pennsylvania State University who has studied frogs in the Caribbean since the 1980s.
"I'm really certain that some species are going over the edge, are disappearing," Hedges said.
Frogs have been under siege around the world from a fungus called Batrachochytrium dendrobatidis, known for short as "Bd," which has been known to be weakening and killing amphibians since the late 1990s though much about it remains under scientific study, Voyles said. Its effects, however, are dramatic.
"When I first went to Panama the sounds at night were incredible and now it's just silent," she said. "It's hard to communicate the absence of that incredible cacophony of beautiful sounds. It's very striking how much we have lost."
Among research efforts on the fungus is one by Lopez and Longo, who have been catching frogs in the forest, checking them for Bd and ticks, and then releasing them back into the night. They have started finding the fungus in the coqui guajon and are still trying to determine how it will affect the population.
After three weeks on the winding back roads of Puerto Rico, politely knocking on people's doors to ask if they could root around on their land for frogs, the researchers were relieved to find plentiful specimens. But they were also dismayed to confirm that one place designated as critical habitat had not a single coqui guajon left.
"To our surprise, the habitat is there, but no frogs, no frogs at all," he said.
Associated Press writer Trenton Daniel contributed from Port-au-Prince, Haiti; Lopez reported from the Dominican Republic; Fox reported from Puerto Rico.
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