Peru is investigating the mysterious deaths of 10,000 endangered frogs that were washed up along the shores of Lake Titicaca and one of its main tributaries over the weekend.

The die-off initially went unnoticed, but authorities were nudged into action on Monday when activists brought 100 frog carcasses into the main square of Puno, the largest town on Lake Titicaca.

“I felt obligated to bring the frogs into town, because officials don't realize how we are living,” Maruja Inquilla, a spokeswoman for the Committee to Clean Up the Coata River, told AFP. “We need a water treatment plant soon.”

The dead frogs belong to the Giant Titicaca Frog species (Telmatobius Culeus), and are about the size of an adult hand. The frogs are endemic to Lake Titicaca and its connecting rivers.

Peru's National Fauna and Forest Service said it conducted a brief field study early this week and found 600 dead frogs within a 600 foot long stretch of the Coaca River. That finding, along with accounts from locals, led scientists to conclude that up to 10,000 frogs could have perished over the weekend from mysterious causes.


A member of Peru´s National Fauna Service picks up frog corpses on the Coata River

Giant Titicaca Frog populations have been threatened previously by hunting and habitat destruction. In Bolivia and Peru the frogs are used for medicinal purposes, and are also served as food to tourists seeking an exotic local meal.

Most of the dead frogs that washed ashore over the weekend were found along the banks of the Coata River, a couple dozen kilometers from the lake. The cause of their deaths is still unclear, but previous studies have warned that water quality in the Coata is deteriorating due to sewage runoff from Juliaca, an upstream town of about 200,000 people.


Illegal mining has also reportedly polluted other rivers in the Titicaca region. The lake is the world's highest navigable body of water, at approximately 3,800 meters above sea level. It is listed as a UNESCO world heritage site, and is frequently visited by gringos backpacking through South America.

Manuel Rueda is a correspondent for Fusion, covering Mexico and South America. He travels from donkey festivals, to salsa clubs to steamy places with cartel activity.