Amphibians are among the lakeshore's more secretive residents. Not surprising for this northern latitude, only 13 species have been confirmed here. Frogs like northern spring peeper, northern green, and wood frog are heard more than seen, especially during the spring mating season. Small gray treefrogs are fairly common but difficult to detect as their superb camouflage hides them in the tall trees where they live. Only their loud trills alert visitors to their presence. American toads are also found throughout the park.
The park's cool, moist woodlands provide perfect habitat and hiding places for salamanders and newts. The permeable skin of these amphibians usually limits them to habitats that are in or near water or other damp places. Park staff monitor the presence of amphibians each year; however locating frogs, toads, and salamanders in the lakeshore's remote forests and wetlands can be quite a challenge. Researchers use special sound recording equipment to determine the presence of various amphibian species by their distinct vocalizations. They also survey some salamanders by conducting egg searches in ponds in the spring.
A bright orange flash scurrying under a log might be a small, slender salamander called a newt. Newts are common and have a complex life history: they hatch in water, live on land as an eft (bright orange juvenile stage), then turn dark in color before returning to the water as an aquatic adult. Red-backed salamanders, which are widespread in the park, live entirely on land as their life cycle does not include a water stage. Pick up logs and branches carefully when collecting firewood as there may be a salamander underneath.
Amphibians generally feed on any prey that is small enough to be subdued and eaten. Insects and other small invertebrate animals comprise the bulk of salamander and adult frog diets. Larval salamanders are also carnivorous, feeding mainly on small aquatic animals such as the immature stages of aquatic insects. Frog and toad larvae (tadpoles) are aquatic herbivores and scavengers, feeding on algae, aquatic plants, and bits of decaying organic matter.
Amphibians worldwide have undergone a decline in the past few decades due to habitat loss and pollutants. Because they are highly sensitive to changing environmental conditions, amphibians are often good indicators of the health of an ecosystem. Little is known about the distribution of amphibians throughout the Lake Superior basin. Monitoring and inventory data from Pictured Rocks, which is shared with other state databases, may help future researchers understand more about amphibian populations in the region and how they might be changing.