Because of their permeable skin, amphibians are often the first animals to suffer when something is wrong with the environment. Habitat destruction, diseases, pesticides and invasive species are among the many threats they face, and these threats can be even deadlier when they work in tandem. For instance, a frog may lose its resistance to a certain disease if pesticides weaken its immune system. Likewise, predatory invasive species are even more dangerous when native frog populations are already vulnerable because of habitat loss.
Why they're in trouble: