Without new conservation measures, there could be a massive die-off of Caribbean frogs within 15 years, warned Adrell Nunez, an amphibian expert with the Santo Domingo Zoo in the Dominican Republic. "There are species that we literally know nothing about" that could be lost, he said.

Researchers such as Lopez and his wife, Ana Longo Berrios, have been fanning out across the Caribbean and returning with new and troubling evidence of the decline. In some places, especially in Haiti, where severe deforestation is added to the mix of problems, extinctions are possible.

It is part of a grim picture overall. The International Union for the Conservation of Nature has found that 32 percent of the world's amphibian species are threatened or extinct, including more than 200 alone in both Mexico and Colombia.

"Everywhere we are seeing declines and it's severe," said Jan Zegarra, a biologist based in Puerto Rico for the U.S. Fish and Wildlife Service.

Frogs may be less charismatic than some other troubled species, but their role in the environment is important. They are consumed by birds and snakes and they in turn are major predators of mosquitoes. Their absence could lead to a rise in malaria and dengue, not to mention discomfort.