Frogs, and their night calls, vanish from forest

** ADVANCE FOR SUNDAY, APRIL 1 ** FILE ** A coqui frog sits on a tree branch in El Yunque rainforest in Caimito, Puerto Rico, Feb. 14, 2002. The tiny frog is named coqui after its distinctive two-note call of "ko-KEE, ko-KEE," and has become a symbol for the island, its culture and its people. Researchers in Puerto Rico blame climate change for the declining of the species in Puerto Rico and nearby islands. (AP Photo/Gerald Lopez)Gerald Lopez / AP file
/ Source: The Associated Press

Back in the Puerto Rican rain forest for the first time in five years, biologist Rafael Joglar sensed something was wrong. He wasn’t hearing the frogs whose nocturnal calls he had long recorded in the misty highlands.

It was as if a small orchestra had lost key players, he recalled.

After that discovery in 1981, Joglar and wife Patricia Burrowes, a fellow University of Puerto Rico amphibian specialist, found that other populations of frogs in the genus Eleutherodactylus — known locally as coquis for the distinctive co-kee sound made by two species — were also mysteriously absent. Similar reports trickled in from frog specialists worldwide, particularly in Central and South America.

Working their way through such suspected culprits as pollution and habitat loss, researchers here eventually zeroed in on climate change. The average minimum temperature had risen from 1970 to 2000 by 2 degrees Fahrenheit, a significant rise for climate-sensitive amphibians.

Scientists believe higher temperatures lead to more dry periods and a chain reaction, at higher elevations, that leaves the frogs vulnerable to a devastating fungus, Burrowes said.

In Puerto Rico and nearby islands, experts believe three of 17 known Eleutherodactylus species are extinct and seven or eight are declining. Loss of the frogs, scientists warn, could have disastrous consequences, depriving birds and other predators of a food source, eliminating a consumer of insects and disrupting the ecosystem in ways impossible to guess.