I’m delighted again to share a guest blog post written by Saunders Drukker. Saunders is an Ecology and Biodiversity major at Sewanee (Class of 2017). 

In my last post on this blog I wrote about how winter was a time of increased activity for the forest dwelling amphibians that inhabit the Cumberland Plateau. Late February is the most active time of all. Towards the end of winter, when relatively warm rains begin to fall, amphibians of all types migrate through the hardwood forest of the Cumberland Plateau and set up temporary residence in water-filled depressions known as ephemeral ponds. Among the animals moving are animals like Upland Chorus Frogs Pseudacris ferriarum, Four Toed Salamanders Hemidactylum scutatum, and Marbled Salamanders Ambystoma opacum. However, the greatest migration is undertaken by the Spotted Salamander Ambystoma maculatum. This relatively large salamander spends the summer and fall in brumation, escaping the dry and the heat in underground retreats, waiting for ecological signals of the breeding season. When the cue of warm rain comes, the salamanders emerge in the thousands to return to the same pools they were born in, where, like their parents, they will engage in the same ritualistic breeding activity.

The males are the first to enter the pond. Here, even without females to impress, they swirl around in the leaf litter at the bottom of the pond, dropping spermatophores (see video taken at the pond on Brakefield Road here). The female salamanders arrive a week or so later. Upon entering the pond the females are swarmed by eager suitors, each waving his pheromones in her face, and gripping her with their legs so as to entice her to pick up their spermatophore, thus passing on their genetic material. After fertilization, the females attach their eggs to a submerged branch, where they swell with water to form a firm gel-like mass. Females come and go fairly regularly, completing their purpose and leaving the pond to return to their forest home. Males tend to stay longer, attempting to breed multiple times, giving themselves a better chance at reproductive success. As the eggs hatch, the pond is filled with thousands of small, gill-flaunting larvae, who in a few weeks will leave the pond on a rainy night to find a place to spend the summer.

Emigration of young salamanders from the pond represents a huge transfer of biomass from an aquatic ecosystem to a terrestrial one. This transfer is one of the most significant roles of amphibians in food webs and ecosystems. These salamanders make up a huge portion of the forest’s vertebrate biomass, and engage in one of the largest movements in the eastern forests of America, and certainly one of the largest here in Sewanee.

All photographs copyright 2016 Saunders Drukker.

 

I’m delighted to share this guest blog post written by Saunders Drukker. Saunders is an Ecology and Biodiversity major at Sewanee (Class of 2017). He’s been studying salamanders and other herps for years. I hope you’ll enjoy his observations and photographs.

As the days here in Sewanee start winding down toward winter, many nature lovers’ subjects begin to disappear. Birds make their way south, mammals start looking for places to hide until spring, and trees go dormant, leaving many of us struggling to find things worth searching for. Thankfully, as everything else goes away, one group begins their most active period of the year: salamanders. Each year in winter salamanders become active by the thousands, moving about the forest floor searching for places to breed.

One of the main groups active at this time year is the Ambystomatids or Mole Salamanders. These stout little amphibians spend much of their year hiding underground, but when the weather cools down and the rains start up they begin to move toward their ephemeral breeding ponds. One of the most striking and most active at this time is the Marbled Salamander, Ambystoma opacum.

These salamanders come out from their underground hideaways and move to the locations of ponds before these depressions fill with water. Here, the salamanders breed and lay eggs in the muddy bed of the pond, where they guard them until the rains come. Once the pond fills with water, the adults return to the forest. The eggs hatch, filling the pool with thousands of larval salamanders. By laying their eggs in the pond before all the other species arrive, the Marbled Salamanders give their young quite the advantage. By hatching earlier than all others, larval Marbled salamanders become large enough to prey upon the smaller larval Spotted Salamanders Ambystoma maculatum once they arrive in spring.

It is not just the mole salamanders moving this time of year, though. The cool wet weather is ideal for almost all species found here on the plateau, especially the lungless species that require cool, wet conditions to be active. These salamanders, as their name implies, do not respire by use of lungs, instead they take oxygen from the environment around them, using their permeable skin to transfer oxygen and carbon dioxide. Some of the most easily found genera in Sewanee are Plethodon, Pseudotriton, Eurycea, Aneides, Hemidactylum, and Desmognathus. 

 

On any rainy cold night large numbers of these salamanders can be found moving across the forest floor, or even across roads, so keep an eye out when you’re driving on backroads. Sewanee boasts a huge diversity of salamanders, and winter is by far the best time to go out looking for them.

All text and photographs on this post, copyright Saunders Drukker, 2015.