By Joseph Marasciullo
Deep within the domain lives a sizable population of Ambystoma maculatum, known better as the spotted salamander. This amphibian inhabits a wide range of wetlands, from Nova Scotia to southern Georgia. Despite being so common, the spotted salamander is relatively understudied by most of the ecological community. Professor Kristen Cecala of Sewanee is an exception: she has devoted two years of study to these fascinating creatures.
To study these salamanders, Cecala and her students constructed an Amphibian Drift Fence. This structure is composed of 270 meters of two-foot high aluminum flashing, and was strategically placed near the end of the salamanders’ migratory corridor. Salamanders approach the fence, and, because their brains are the size of popcorn kernels, decide not to turn around and walk along the wall until they fall into one of the buckets. These buckets are then collected by biology students, who process the salamanders and then return them back to the wild. Other species have made guest appearances as well, such as snakes, spiders, and even turtles.
A big question Cecala and her students hope to answer with the construction of this wall is when and why the Salamanders migrate. We know factors that drive their migration include time of year, temperature, and moisture; however, we don’t know what combinations of these factors incite migration. It’s like having a recipe without knowing the measurements. Cecala’s research has uncovered that wet, warm nights during the vernal period trigger mass migration. Right now, Cecala estimates that there are about 2,000 salamanders living on the Domain, and has observed them moving in groups of around 650. Once they reach their destination, they lay eggs in the vernal pools, leaving the salamander eggs to develop alone over the course of one to two months.
The salamanders here may be privileged, but in other non-protected woodland areas, salamanders are often in conflict with human advancement. Sometimes the vernal pools that salamander communities flock to each year are ruined by houses or roads. Climate change also plays into their migration and can lead to salamander populations migrating earlier than usual. This isn’t a problem for the spotted salamanders: the earlier migration gives the hatchlings more time to mature. The most pressing concern for the spotted salamander is habitat loss. In addition to their migratory range, spotted salamanders inhabit wetland areas; however, they do not venture outside of a 300 meter circle. Unfortunately, wetlands are disappearing all across the country. The WARPT, or Wetlands-At-Risk Protection Tool, a site developed by the Center for Watershed Protection in conjunction with the EPA, estimates that over half of all wetlands existing since the discovery of the United States in the 1600’s have been lost to various factors, including human development and pollution. If we continue to pollute and destroy our wetlands, we lose not just the spotted salamander, but our natural surroundings as well.