Slithers in the Night

The reclusive Jefferson salamander is an important indicator of wetland health.

Illustration by Jeremy Sancha

If running around in the dark, high in the mountains, on a cold, wet, late-winter night is not your idea of a good time, then you might want to strike a sighting of the Jefferson salamander from your bucket list. 

Not one of your more flamboyant salamanders (“fairly nondescript” is the verdict from the Virginia Department of Game and Inland Fisheries), the more-or-less mud-colored Jefferson salamander is also an amphibian of retiring habits. It earns its membership among the “mole” salamanders by leading most of its life below ground and out of sight, explains University of Richmond assistant professor of biology Dr. Kristine Grayson. Preferring undisturbed woodlands, Jefferson salamanders inhabit the far western, mountainous part of Virginia, and for 10 to 11 months of the year live immersed amidst the forest leaf litter or secreted in subterranean burrows.

And while there, they do not exactly get up to all manner of business, either. These salamanders are ectotherms, with a very low metabolic rate, and thus need to feed only infrequently. “A good meal [worms, crickets, other invertebrates] holds them for a long time”—as long as a month in a laboratory setting, says Grayson—and for most of the winter they’re less active still, quite literally chilling out below the frost line. In short, for much of the year, a day in the life of a Jefferson salamander makes a Zen retreat look like a weekend at Burning Man. 

But then!

In that uncertain transitional interlude when winter has loosened its grip but spring has yet to fully take command, the Jefferson salamander is called forth. Exactly what motivates it remains a matter of some speculation, according to the Virginia Herpetological Society—it’s assumed to be some combination of changing light, rising temperature, increasing humidity, a warm rain. But whatever the signals, the result is that the salamanders all leave their sheltered retreats and converge on shallow, seasonal wetland ponds, known as vernal pools, to breed. 

If all goes well, the Jefferson salamander’s timing is advantageous. As spring advances, vernal pools host an increasing variety of amphibians, insects, and other small aquatic creatures, as well as growing numbers of predators drawn to the abundance. But Jefferson salamanders, joining wood frogs as the earliest arrivers, get a jump on all that. Like an amphibian flash mob, “They will all flood a wetland at once, and they will be there in a really high concentration,” says Grayson.

Which is where the cold, wet, dark night comes into the story: If you hope to see a Jefferson salamander, this is your hour, says Grayson. A 40-degree rainy night at two in the morning? “The best time to go out and see them,” she says cheerfully, having done just that while conducting her graduate research on these salamanders. Even under such salubrious (for a salamander) conditions, though, a sighting is not guaranteed. “They’re very dark-bodied, so even in the water they are difficult to see,”says Grayson. 

It’s also true that being the first ones to the pool doesn’t always turn out well. While they can tolerate fairly cold conditions, even moving under a layer of snow to reach their breeding ponds, “They are really vulnerable to changes in spring conditions,” says Grayson.“If you get a couple of warm days and these salamanders start moving, and then it gets really cold again and doesn’t warm up, they can be affected.” 

In favorable conditions, however, the females will lay a few hundred eggs in the pond, which hatch into larvae sporting feathery external gills. After about three months in the pool, the larvae metamorphose into their adult form, lose the gills, develop lungs, and head for the woods. Then it will be another two to five years before they reach sexual maturity, at which point they return to breed in the same pond where they hatched. It’s not easy for researchers to track how many of the salamanders successfully run that years-long gantlet from egg to reproducing adult, but it’s probably not many. When you’re a small amphibian on the lower rungs of the food chain, life is a numbers game, and even in ideal conditions there are inevitable boom and bust years. So while hundreds of juveniles may leave the pond, says Grayson, if only two survive to maturity for every adult salamander, that’s a replacement rate that will hold the population steady.

That’s a fine line, though, making these salamanders highly vulnerable to habitat degradation or loss and thus an important “indicator species” for the health of both the wetlands and forests where they live, says Grayson. They may be nondescript, reclusive amphibians most of us will never lay eyes on—but as go the salamanders, so go us all.

This article originally appeared in our February 2019 issue.

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