By Nicholas Gaye, Interpretive Naturalist

When we think of spring migrators, we often associate the phrase with the fallout of tropical warblers returning from their southern abodes back to the parks. Perhaps the monarch butterfly’s journey from its Mexican overwintering ground comes to mind. But there is another lesser-known migrator, far more mysterious and elusive than the other two–a slimy family of amphibians known as mole salamanders. Mole salamanders belong to the genus Ambystoma, and unlike many salamanders that hang out in streams, mole salamanders spend most of their time burrowing underground. They spend the majority of the year scouring through the substrate in search of invertebrate prey including slugs, grubs, or bugs–anything that is small enough and spends its time underground is fair game for a mole salamander’s diet!

Jefferson salamander

There are four mole salamander species native to Northeast Ohio–some of which you can find in the parks! Spotted salamanders (Ambystoma maculatum) are the most common mole salamander and the ones you are most likely to encounter. They utilize both upland and lowland forests, so their vernal pools can be found in either habitat. The other two spring migrators are Jefferson (Ambystoma jeffersonianum) and Small-mouthed (Ambystoma texanum) salamanders. They are very similar in appearance but reside in different habitats. Jefferson salamanders utilize upland forest habitat, so if you find yourself in an upland forest vernal pool, you are most likely to find Jefferson and spotted salamanders. If you are in a lowland forest habitat, you are likely to encounter small-mouthed and spotted salamanders.

Spotted salamander

Small-mouthed salamander

The final mole salamander is far less abundant than the others and they migrate much later in the year than the others. The marbled salamander (Ambystoma opacum) saves its migration for the autumn, performing a migration under identical conditions to the species that run during the spring. These salamanders usually migrate with warm rains that come in from the Gulf of Mexico with late seasonal hurricanes.

Marbled salamander

With the abundance of food and inherent safety underneath the surface, why do they need to migrate? Well, just like every other good story, it’s all in the name of love. Mole salamanders migrate once every year, emerging from their subterranean network to return to the very same vernal pools they were born in. Here they participate in an elaborate mating ritual, encircling one another as they try to impress a potential mate with their elegant dances. They remain in the pool for only a matter of days before the ritual is over and thousands of fertilized salamander eggs replace their parents. A single female can lay 100 to 300 eggs in a single mating season!

Salamander eggs

It is imperative that these salamanders have particular conditions for their migration. For starters, mole salamanders only migrate under the cover of a night sky. This minimizes their interactions with predators to ensure safe passage back to their pools. Since they are ectotherms (cold-blooded), mole salamanders need it to be warm to migrate, so temperatures must be above or around 50°F for the entirety of the night. Conditions must be damp because amphibians must be consistently wet to diffuse air through their skin. Fresh snow melt and rains aid in this and also in filling up the vernal pools they return to.

Vernal pools are an integral facet of the migration and without them there would be far fewer frogs and salamanders in general. The importance of vernal pools stems from the fact that they are ephemeral, or temporary, pools of water. They dry and fill up according to our seasons and how wet the conditions have been. Because of this, these pools are disconnected from a source of water such as a stream or lake. That makes these pools the optimal breeding grounds for amphibians because they are absent of fish (who like to feed on eggs). Without fish present, salamanders are able to develop and emerge without fear of predation. However, this does not remain the case into adulthood. Mole salamanders have a number of predators that feast on them: from dragonfly and damselfly larvae feeding on them in vernal pools, to skunks digging them up out of their burrows, these amphibians have their work cut out for them.

If you’re interested in joining Lake Metroparks for a salamander migration run, click here to sign up for our email list. Join naturalists as we discover and discuss these amazing amphibians!