Since frogs have very permeable skin, they are very susceptible to chemicals in the environment. Ecologists consider frogs to be bioindicators of environmental problems. Changes in the environment whether due to chemicals or temperature tend to affect the frog populations first. In some respects, they are the canary in the coal mine for our environment. That’s why I’m always glad to see them when I go home to visit. If the frogs are healthy, then chances are the lake is healthy. Below, I’ve included several pictures of the frogs native to my home in northern-Wisconsin.