It may surprise many Minnesotans to learn that seven species of salamanders reside in our state. The lives of these secretive amphibians rarely cross paths with our own. In Minnesota, spotted salamanders (Ambystoma maculatum) weren't documented until the spring of 2001 during surveys conducted by the Minnesota Biological Survey. The spotted salamander is a forest species more common in the eastern United States.
This elusive species was documented in Minnesota on April 26, 2001 when seven spotted salamander egg masses were located in a shallow wetland within the Nemadji State Forest.
The wetland's rich amphibian diversity also included egg masses of the blue-spotted salamander and wood frog. Adult spring peepers, and wood frogs called along the wetland's edge, and Eastern Red-backed Salamanders and four-toed salamanders were found under logs on the surrounding forest floor. Unfortunately, having finished their breeding activity, adult spotted salamanders had returned to their forest burrows and were not found at the wetland.
Egg masses of the spotted salamander are unique due to their large, gelatinous character, but can be confused with wood frog or tiger salamander egg masses. All three species lay globular, fist-sized egg masses in shallow water. Wood frogs have 500 or more eggs per mass that are often laid in communal groups. Tiger salamander egg masses have approximately 50 eggs per mass, compared to 75 to 100 eggs per spotted salamander egg mass.
While the egg masses and habitat matched the description for spotted salamanders, the significance of finding a new state record required confirming the species identification. One egg mass was collected and kept in a small aquarium filled with pond water. On May 16, 2001, wriggling salamander larvae were observed emerging from the egg mass. Newly emerged spotted and tiger salamander larvae are quite similar, however, young spotted salamander larvae have balancers near their gills. Tiger salamander larvae lack balancers. Viewing the balancers under a dissecting scope confirmed the spotted salamander's identity.
Balancers found on spotted salamander larvae.
What is the significance of documenting spotted salamanders in Minnesota? Although rarely encountered, these creatures are a part of our natural heritage and are dependent on our abundant wetlands and diverse forests. Now, their habits and habitat needs can be taken into account during forest management activities. Amphibian populations are declining around the globe and the need for current information on species distribution is great. In the coming years, MBS surveys will work toward learning more about the distribution of Spotted Salamanders in Minnesota.
If you think you've seen spotted salamanders in Minnesota please e-mail Carol Hall with information about the date and location of your observation. Please look closely at the salamander to distinguish it from the tiger salamander. Use this ID sheet to help. When possible, please include a digital image of the salamander with both dorsal (top) and ventral (bottom) views.
Ventral (bottom) views of spotted salamander (left) and tiger salamander (right).