Wednesday, November 10, 2010
Miners working underground used to use canaries in cages to warn them of imminent danger from poisonous gases. The tiny bird was vulnerable to even trace amounts of deadly gas. If it stopped singing and keeled over, the miners knew they needed to get out of the shaft as fast as they could.
Amphibians are "the canary in the coal mine" for the entire earth, and their rapid decline over the past three decades is telling us we need to address our environmental crisis quickly and decisively. Unlike the coal miners, we can't exit the danger zone, which is now everywhere. A global amphibian assessment published by the International Union for Conservation of Nature (IUCN) in 2004 reported that 32% of amphibian species were globally threatened, at least 43% were experiencing population decrease, and that as many as 122 species were extinguished entirely between 1980 and the turn of the century.
This is happening because, like the canary in the mine, amphibians are more sensitive to environmental changes than other creatures. Their unique life cycle includes both aquatic and terrestrial stages, making them vulnerable to changes in either the water conditions of their habitats or those on land. Their skins are more permeable than those of other creatures, making them more susceptible to toxins in the environment. Exposure to common pesticides and herbicides dramatically increases mortality among tadpoles. Ozone depletion and the resulting increases in ultraviolet radiation are also factors in the world-wide die off of frogs, toads, and salamanders.
The golden toad of the Costa Rican rain forest used to be a favorite subject for scientists studying the relationships between fragile environments and the creatures who thrived only in those habitats, until its population crashed in 1987 and the species disappeared entirely two years later. This little toad is "the canary in the coal mine" for the entire earth.
In Aristophanes' play The Frogs, written and first performed in 405 BCE, the god Dionysius is rowed across the River Styx by the ferryman Charon, who will convey all of us to the land of the dead sooner or later. It's here that the frogs make their only appearance in the play, chanting "Βρεκεκεκέξ κοάξ κοάξ" (Brekekekéx-koáx-koáx), and Dionysius idly sings the refrain along with them as Charon's boat glides silently over the black water. We're in that exact same situation today, and like the long-departed god of ancient days, we'll know we've reached the other side when we can no longer hear the song of the frogs.