Amphibians
Pygmy Salamander
Desmognathus wrighti · also called pygmy dusky salamander
Near the top of the highest peaks in the southern Appalachians, in the cold wet forest of spruce and fir, lives a salamander small enough to sit on a coin. On rainy nights it does something most salamanders never do: it climbs the trees.
Overview
Desmognathus wrighti is one of the smallest salamanders in the world, about 3.5 to 5 cm including the tail. It lives only in the high-elevation spruce-fir forest of the southern Appalachians, generally above 1,500 m, in moss, bark, and leaf litter. It is lungless, breathing through its skin.
A tree climber with no tadpole
On warm, wet nights it climbs spruce trunks and shrub stems, sometimes over a metre up, to feed and to escape ground predators. The female lays a small egg cluster in wet moss and guards it, and the eggs hatch straight into tiny salamanders with no aquatic larval stage.
Status
Least Concern and still locally common on the peaks, but its range is a scatter of mountaintop forests left behind by the last ice age, and those forests are shrinking under an introduced fir-killing insect, acid deposition, and a warming climate that pushes its cool zone off the top of the mountain.
Pygmy Salamander: common questions
How small is the pygmy salamander?
An adult is roughly 3.5 to 5 centimetres long including the tail, which puts its body alone at around 2 centimetres, small enough to curl up on a coin. It is the smallest member of the dusky salamander group and among the smallest salamanders anywhere; only a few tropical species and some other tiny plethodontids are in the same size class. Its small size is linked to living in moss and leaf litter, feeding on the smallest invertebrates, and developing directly from the egg without needing to reach a size where it could survive in open water as a larva.
Do salamanders really climb trees?
Some do, and the pygmy salamander is one of the more committed climbers. On humid nights, when the bark and vegetation are wet enough for a skin-breathing animal to stay moist, pygmy salamanders ascend the trunks of conifers and the stems of shrubs, and they have been found well over head height. Climbing gives them access to prey and to damp bark crevices, and it lifts them away from the larger salamanders and the ground predators that dominate the forest floor. The green salamander, which lives in rock crevices and on trees, is another Appalachian climber.
Why is it found only on mountaintops?
Because it needs the cool, wet conditions of high-elevation spruce-fir forest, and in the southern Appalachians that habitat exists only as isolated caps on the highest ridges and peaks. During the last ice age this kind of forest covered much lower ground, and cool-adapted species like the pygmy salamander lived across a wide area. As the climate warmed after the ice age, the spruce-fir zone retreated upslope, and the salamander retreated with it, ending up marooned on separate mountaintops like islands in a sea of warmer forest. Further warming shrinks those islands.
Is the pygmy salamander endangered?
It is currently listed as Least Concern because it remains fairly common on the peaks where it occurs, but its situation is fragile. Its entire world is a scatter of mountaintop forests with a combined area that is not large, those forests are already stressed by an introduced adelgid insect that kills Fraser fir, by historical logging, and by air pollution, and the cool climate zone it depends on is moving upward and running out of mountain. Biologists regard it as a species to watch closely rather than one that is safe.