Amphibians have high potential as indicators of changes in the environmental quality because of their biologic sensitivity and a life cycle that involves both aquatic and terrestrial habitats for many species. Male frogs and toads advertise their presence to females by singing, each species having its own distinct call. There are 11 species of frogs and 1 toad, collectively called "anurans", in Wisconsin.
The Wisconsin Department of Natural Resources (DNR) has been coordinating statewide frog and toad surveys since 1984. In cooperation with the DNR's monitoring program, the Lakeshore audio frog and toad surveys were begun in 1990 to determine long-term statewide population trends. As a protected area, Apostle Islands may also serve as a control against which population trends could be compared with intensely managed areas. Apostle Islands provide prime habitat for amphibians that includes mixed hardwood and boreal forests, bog, lagoons and streams of the. Typical species of the mixed hardwood forest found in the park include the Spotted Salamander, Gray Treefrog, Northern Reed-bellied Snake and Northern Ring-necked snake. In the moister forest Wood Frogs, Blue-spotted salamanders, Red-backed salamanders are found, while Mink Frogs and Northern Leopard Frogs inhabit pond and lake edges. Some of the hardy amphibian and reptile species that survive in a variety of habitat types within National Lakeshore are Northern Spring Peeper, American Toad, Painted Turtle, and Common Garter Snake.