Three species of frogs native to the mountains of Puerto Rico have apparently disappeared from several critical habitats, a sign that a long decline in amphibians on the island shows no signs of letting up.
Scientists on Thursday blamed the decline on climate change, habitat destruction and a fungus known as "bd" or Batrachochytrium dendrobatidis, which has killed dozens of amphibian species worldwide.
The species most at risk in Puerto Rico is the mountain coqui, which is now found only in portions of El Yunque forest and another forest in the island's southern region, said Rafael Joglar, a herpetologist at the University of Puerto Rico.
"This species has basically retreated to the highest and coldest mountains of Puerto Rico," he said. "The problem is that it has nowhere higher to go."
It is one of the island's 17 endemic coqui species, which have long been a popular symbol of the U.S. territory.
The mountain coqui once lived in the western part of the island and across its central mountain range, but numbers there have since dwindled, and in some cases disappeared, said Jan Zegarra, a Puerto Rico-based biologist for the U.S. Fish and Wildlife Service.
"People love the coquis of Puerto Rico, but they don't realize what's going on," Joglar said. "We don't need more investigations to protect this species. There is enough evidence to warrant protection."
While the coqui is originally from Puerto Rico, it has been found in Costa Rica and has formed large colonies in Hawaii, where it has no natural predators.
Joglar previously rejected the idea of breeding frogs in captivity to ensure their survival in Puerto Rico, noting they have died when introduced into the wild as adults, but he said that may be the only alternative now.
Scientists are using breeding programs in an attempt to save another one of the island's endangered species, the Puerto Rican crested toad. The Nashville Zoo in Tennessee has sent more than 5,000 tadpoles to the U.S. territory, while the Buffalo Zoo in New York has sent hundreds of tadpoles in an effort to rebuild the wild population.
© 2013 The Associated Press. All rights reserved.