Natural History: Desmognathus auriculatus

During our last field trip while turning over logs near a swampy area our class discovered a Desmognathus auriculatus, or Southern Dusky salamander. This is the only species within the Desmognathus family to occur within our area and therefore was quite easy to identify. Distribution of the Southern Dusky salamander occurs along the coastal lands of Southeastern US- along southern Virginia down to Florida and across the Southern US extending into Texas.

This salamander is typically between three to five inches long and dark in color with a single row of spots or "portholes" starting behind the front leg and extending slightly beyond the hind legs (onto the tail) on each side. This can be seen below as white spots going down the side of the salamander.

We were able to identify the salamander as a Desmognathus due to the enlarged hind limbs (as compared to the forelimbs) and the light stripe that extends downward from the eye. The tail is vertically keeled and wide at the base near the hind limbs. There is a lot of variation among local populations for this salamander sometimes making it hard to identify. In identifying the sex of the species, beyond the cloaca possibly swelling during breeding season there are no physical characteristics to set the two sexes apart (in the currently studied populations). It is possible that the adult males defend their territory and reach sexual maturity at an earlier age than females. 

This species tends to live under logs or natural debris in mucky, acidic environments where lots of decomposition occurs. Charleston has lots of this in the coastal plain habitats, but the species also thrives in river flood plains The specific Southern Dusky salamander was discovered under a log in shallow water next to a swamp. 

Reproduction for D. auriculatus is semi-aquatic after which the eggs are laid on land near water. Parental care is used to keep the eggs at a constant warm temperature. Once hatched, the larvae transition to the water nearby. Females lay clusters of eggs in beneath logs or bark, moss, and in stumps close to water. Due to the parental care necessary, the clutch size is typically between 9-25 eggs.

In the field, these creatures are not known to migrate and during a drought they have been observed burrowing into the ground for prevention of dessication. In the presence of a predator, they are known to burrow into the soil or retreat into crayfish holes while whipping back and forth to avoid getting caught. 

Unfortunately, not much research has been done on this salamander. Behavior, conservation measures, predator species, and other ecological facts are still largely unknown. Finding this little guy was quite exciting as it seemed to be a rare find and the salamander was very interesting. It's bubbly eyes, over sized hind limbs, and patterns made it quite the adorable creature. I worry that the rarity of this species is due primarily to negative human interactions (as are most things) since the salamander does not migrate, has small clutch sizes, and uses both land and water as habitats. The variability of all of the different local populations of this species could hold valuable information and also serves as an indicator of how incredible nature truly is.

Works Cited

AmphibiaWeb: Information on amphibian biology and conservation. [web application]. 2012. Berkeley, California: AmphibiaWeb.  

Conant, Roger, and Joseph T. Collins. A Field Guide to Reptiles & Amphibians: Eastern and Central North America. 3 Expanded ed. Boston: Houghton Mifflin, 1998. Print.