Ten new species of amphibians -- including three kinds of poisonous frogs and three transparent-skinned glass frogs -- have been discovered in the mountains of Colombia, conservationists said Monday.

With amphibians under threat around the globe, the discovery was an encouraging sign and reason to protect the area where they were found, said Robin Moore, an amphibian expert at the environmental group Conservation International.

The nine frog species and one salamander species were found in the mountainous Tacarcuna area of the Darien region near Colombia's border with Panama.

Because amphibians have permeable skin, they are exposed directly to the elements and can offer early warnings about the impact of environmental degradation and climate change, Moore said. As much as one-third of all amphibians in the world are threatened with extinction, he said.

"Amphibians are very sensitive to changes ... in the environment," Moore said in a telephone interview. "Amphibians are kind of a barometer in terms of responding to those changes and are likely to be the first to respond, so climate change ... impacts on amphibians heavily."

Amphibians also help control the spread of diseases like malaria and dengue fever, because they eat the insects that transmit these ailments to people.

The new species discovered in Colombia include three poison frogs, three glass frogs, one harlequin frog, two kinds of rain frogs and one salamander.