Story highlights Authorities: More than 10,000 Peruvian frogs have died

Denver Zoo specialists working with Peru to study samples

(CNN) Peruvian authorities want to know why more than 10,000 endangered frogs living near Lake Titicaca have suddenly died.

The Titicaca Water Frog is considered a "critically endangered" species, according to conservation groups. The giant amphibians, which can weigh more than two pounds, have excessive skin folds that have earned the species a rather wrinkly nickname: scrotum frog.

Over the past two decades, authorities say the giant frogs have become threatened due to over-harvesting for human consumption, exotic trout that feed on its tadpoles, and the destruction of their natural habitat.

While no one knows exactly why they're dying now, those threats have dramatically decreased their population, authorities said.

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Maruja Inquilla Sucasaca, who represents the Committee to Combat Pollution of the Coata River, reported the deaths to the Peruvian National Forest and Wildlife Service. The Coata River passes through Puno, a lakefront city in southeast Peru, and ends at Lake Titicaca's Chucuito Bay.

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