SEASON OF THE salamander
Winter is a busy time for hellbenders, other species in Tennessee
Winter is a difficult time for many animals. Food is scarcer and the temperature is colder. Starvation is a huge threat.
Many mammals, amphibians and reptiles spend East Tennessee’s colder months hunkered down in burrows waiting for warmer weather. Even if they aren’t hibernating, animals like raccoons, rattlesnakes and bears become far less active to stay alive.
But for some creatures, winter is the busiest time. From deep in the Appalachian soil, to mountain streams, to sunlight forest pools, salamanders stir.
“In general they are pretty active in the winter,” said Stephen Nelson, herpetology collection and conservation coordinator for the Knoxville Zoo. “You’ll typically find them in pretty good numbers in late fall, early winter when a lot of them are moving around on the surface.”
Salamander capital of the world
There are more salamander species that call the Southern Appalachians home than any other place on Earth. There are 30 salamander species present in the Great Smoky Mountains National Park. Out of the 550 known salamander species on the planet, 77 live here in our backyards. Their bright colors make them the living jewels of Appalachia.
According to the Great Smoky Mountains Institute at Tremont, the population of salamanders in the park is so high that they would collectively outweigh all the mammals in the park. All those hungry mouths keep insects under control, especially mosquito larvae in forest pools. But salamanders are often hard to find, because many are reclusive, living hidden under leaves or deep in burrows. This time of year is different.
This might seem a little paradoxical because salamanders are ectothermic or “cold blooded.” They don’t produce their own body heat. Other ectothermic animals, like snakes and anoles, are usually less active this time of year.
“Their lower thermal temperature that they are active at is much lower than most species of frogs and certainly most reptile groups.” said Brian Miller, a professor of biology at Middle Tennessee State University. “You’ll see them in some areas walking over snow.”
The forest floor provides a blanket of leaves to insulate them. On the coldest days, they dig downward or shelter in caves to take advantage
of the ambient heat of the earth to avoid killing frost. Aquatic salamanders like mudpuppies can stay active below the ice, at colder temperatures than fish.
And for most of them, the forest floor is still full of food so many invertebrates are still alive in the leaf litter. Predatory salamanders that frequently feed on other salamanders have no trouble finding food this time of year.
Breeding season
Many salamanders come out to breed this time of year when forests are moist and quiet. As the trees go into senescence for the winter, they stop drawing moisture into their roots. As it rains, this water collects in temporary, vernal pools in the forest. These pools appear year after year and are the perfect habitat for many salamanders to lay eggs.
“They’re going to breed in fish-free bodies of water,” said Miller. He explained that vernal pools are either low or dry right now. Some salamanders lay their eggs in dry pools to await the coming of water, others wait for pools to fill, freeze and thaw.
Salamander eggs are darkly colored to absorb sunlight through the open canopy to keep themselves warm enough to grow. By the spring, they’re ready to hatch, just in time for insects and other invertebrates to return.
The precise timing of salamander breeding is controlled by the weather and climate. Salamanders are very sensitive to changes in temperature and moisture. Over millions of years they have evolved to lay eggs at the times when
they will be safest and hatch when food is plentiful. Salamanders in the Southern Appalachians time things later than salamanders in the north in part because the climate is milder.
Not all salamanders follow the same patterns or come out for the same reasons. Zigzag salamanders spend most of their time deep underground and migrate to the surface to avoid drowning in the water-logged winter soil. Miller said you can find them hiding out by the dozens under piles of wood if you have a creek, pond or forested pool nearby.
Hellbenders get done early
Hellbenders are the largest salamanders in North America, growing to roughly two feet long. They begin breeding in September and can continue into November. For them, winter is the optimal time to hatch. Fish, which will eat larval salamanders, are slower and less active when the water temperature drops in winter.
Hellbenders live in streams with cold water, swift currents and stony bottoms. During the breeding season, males dig out large nests in the river bottom and aggressively guard them from rivals. Female hellbenders lay eggs in the nests that are then guarded by males for a period of between 45-75 days until the eggs hatch.
Miller explained that by end of the year, most hellbender dads should have moved on from guard duty, but each stream is timed a little differently.
During the rest of the winter, hellbenders spend their time snacking on crayfish and giant dobsonfly larvae.