By Annie Perry, MNA Intern
For many Michigan residents, there are a few tell-tale signs of spring: Springtime birds chirping after being gone for a long winter, green grass growing, flowers sprouting, and days getting longer. But MNA stewards have one more thing to tell them that spring is here: Salamanders and other amphibians migrating to vernal pools.
Each spring, amphibians make mass (well, mini) migrations to vernal pools and ponds, usually at night during or after the first warm rainstorm. Once at the vernal pools, these amphibians will mate and lay their eggs before returning to the forest. Dave Richmond, a steward at the Edna S. Newnan Nature Sanctuary in St. Clair County, spotted some of the first salamanders of the season early this month—which means spring must be here, after all.
Vernal pools are natural, temporary bodies of water that occur in a shallow depression. These pools typically fill during the spring or fall and may dry in the summer; have no viable populations of fish; and provide essential breeding and nursery habitat for several organisms, including amphibians. Many amphibian eggs have physical properties or toxic compounds that help deter predators, but amphibians that are dependent on vernal pools lack these protections. As a result, their eggs and young are vulnerable to both aquatic and terrestrial predators. Not all vernal pools dry up every year, but each pool has some feature that prevents fish from living there, such as low oxygen concentrations during the summer or shallow levels that allow the pool to freeze to the bottom during the winter.
The spring issue of Michigan Nature magazine includes a feature on vernal pools—keep an eye out to learn more about these unique and important habitats!