Desmognathus fuscus
dusky salamander

Northern dusky salamanders occur from southern New Brunswick and Quebec, along the East Coast to North Carolina, and west to Ohio, southern Indiana, Kentucky, and Tennessee. Over most of their range, dusky salamanders are common in appropriate habitat. Their distribution in the southern Appalachian Mountains is sporadic. Desmognathus fuscus recently included three subspecies, which continued the range to the Gulf Coast. Most authorities now consider these to be separate species. See "Other Comments" below for further information. A breeding population of Desmognathus fuscus has been found at one site in eastern Michigan; whether this population is introduced or a natural relict has not yet been determined. (Bartlett and Bartlett, 2006; Bonnett, 2002; Conant and Collins, 1998; Harding, 1997; Petranka, 1998)

Northern dusky salamanders prefer wooded or partially wooded moist habitats with running or trickling sources of water. Most often, they are found under flat rocks or logs near rocky or hillside streams or seeps, or in the moist, misty habitat near waterfalls. They may go into the water to find cover under rocks or substrate if disturbed. If the stream substrate does not freeze, they can remain active year-round. In extremely cold conditions, they will burrow under gravel until they are below the frostline. Dusky salamanders can survive at a variety of altitudes, ranging from sea level to high in the Appalachian Mountains. In the Great Smoky Mountains they are uncommon over 1200 m in elevation. (Bartlett and Bartlett, 2006; Conant and Collins, 1998; Harding, 1997; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

Desmognathus fuscus is a small but robust salamander with 14 costal grooves, and hind limbs that are larger than the front limbs. They have a keeled (knife-like) tail that is less than half the body length. The upper body varies from brown or reddish brown to gray or olive, with slightly darker markings on the top and sides. The base of the tail is typically olive, yellow, or bright chestnut (a bit lighter than the body). The belly is whitish with some dark speckles. Adults are 6.4 to 14.2 cm (2.5-5.6 in) in length. Males are typically longer than females. The average length for a male D. fuscus is 9.4 cm, and the average length for a female is 8.6 cm. Desmognathus fuscus is in the family Plethodontidae, and thus is lungless. They “breathe” via oxygen absorption through the skin and membranous tissue in the mouth and throat. Also, members of this family have a naso-labial groove, which may aid in smelling, which is important when finding prey and identifying potential mates. (Bartlett and Bartlett, 2006; Bishop, 1941; Conant and Collins, 1998; Harding, 1997; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

Upon hatching, dusky salamander larvae are about 1.6 cm (0.6 in) long and have well-developed limbs. The larvae may stay with their mother for several days or even weeks before going to the water. Because they are aquatic, they have gills, which are small and white. However they can survive in moist terrestrial environments for some time if required, and terrestrial metamorphosis may be possible. After spending 7 to 11 months in the water they undergo metamorphosis (in the spring or summer after hatching). Newly transformed salamanders are 2.8 to 4.4 cm (1.1 to 1.7 in.) long. (Bishop, 1941; Harding, 1997; Hom, 1987; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

No specific information is available on longevity in this species. Related salamander species can be relatively long lived (i.e. several years to a decade or more) for such small animals. (Petranka, 1998)

Dusky salamanders are mainly active nocturnally. At night, they will leave the log or rock that gives them protection during the day to find food along a steam or waterway. On moist evenings, salamanders are active from dusk to dawn. While mostly terrestrial, dusky salamanders can sometimes climb up vegetation or rock faces. These salamanders can be active throughout the year if in a spring or spring-fed habitat, but often are inactive in winter. They are generally solitary except during courtship and mating, and larval brooding. (Bishop, 1941; Gibbs et al., 2007; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

Home Range

Adult dusky salamanders have a small home range, and an individual may move only a couple of meters over a period of several months. The actual size of the home range varies between localities and geographic range, ranging from 1.4 square meters to 114 square meters. (Bishop, 1941; Gibbs et al., 2007; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

It is thought that the nasolabial groove (characteristic of members of the family Plethodontidae) aids in smelling prey items as well as potential mates. Chemical odors may be transported along the groove and into the mouth, where the vomeronasal organ can transfer the information to the salamander's brain. Also, glands (like the mental gland, located on the chin) are used to communicate with mates when courting. The male will vigorously rub his chin onto the female, as well as bite her, in order to provide her with pheromone secretions until she becomes fully receptive. If a brooding female is returning to her nest after feeding at night, she can recognize which clutch is hers by using chemical cues. Dusky salamanders may bite a threatening predator. Also, a male may attack a another male that is courting a female. (Harding, 1997; Petranka, 1998)

Dusky salamanders are carnivorous, and eat small invertebrates (both terrestrial and aquatic) including earthworms, slugs, snails, crustaceans, spiders, mites, flies and fly larvae, ants, beetles and beetle larvae, centipedes, moths, and mayflies. Dusky salamander larvae eat crustaceans, insect larvae, copepods, and mites. The diet is fairly nonspecific, and they tend to eat whatever is in abundance. Dusky salamander larvae or small juveniles are occasionally eaten by large adults. (Bishop, 1941; Harding, 1997; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

Dusky salamanders have a number of predators, including raccoons (Procyon lotor), birds, striped skunks (Mephitis mephitis), shrews (family Soricidae), water snakes (Nerodia species), garter snakes (Thamnophis species), spring salamanders (Gyrinophilus porphyriticus) and red salamanders (Pseudotriton ruber). It has been suggested that predation may impact reproductive success to the point that it restricts the abundance of dusky salamanders in parts of their range from Tennessee to Virginia. Dusky salamander skin is only mildly toxic, so they must rely on other defensive techniques. Dusky salamanders can move with great agility, and are good jumpers. They also have slippery skins which makes grasping by predators difficult. They may actually bite a predator. Like many of the plethodontid salamanders, they can drop their tails when attacked in order to distract the predator enough to make a quick escape. The tail will grow back later, though it may look slightly different than the original. Tail dropping is fairly common in northern dusky salamanders; approximately 50% of adults have missing (recently dropped) or regrown tails. (Bartlett and Bartlett, 2006; Bishop, 1941; Gibbs et al., 2007; Harding, 1997; Hom, 1987; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

Dusky salamanders are second and third order consumers that eat a wide variety of small terrestrial and aquatic invertebrates. They are opportunists and will eat whatever is available in high abundance. Dusky salamanders are prey to a number of animal species representing many vertebrate (and perhaps some invertebrate) groups, including mammals, snakes, birds, and larger amphibians. Desmognathus fuscus often shares its habitat with other species of the genus Desmognathus, and other plethodontid salamanders. It appears that niche partitioning occurs, and animals of the different Desmognathus species have a broader habitat preference in areas of overlap than in areas that the species do not overlap. Other species that have been found to coexist with D. fuscus are seal salamanders (D. monticola), Allegheny Mountain dusky salamanders (D. ochrophaeus), southern dusky salamanders (D. auriculatus), and northern two-lined salamanders (Eurycea bislineata). (Bartlett and Bartlett, 2006; Bishop, 1941; Harding, 1997; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

There are no known adverse effects of Desmognathus fuscus on humans.

In the southeastern United States, salamanders in the genera Desmognathus, Gyrinophilus, and Pseudotriton are collected and sold as fishing bait for largemouth bass (Micropterus salmoides) and other sport fish. In bait shops, you can find them labeled as "spring salamanders" or, as often, "spring lizards." The lungless (plethodontid) salamanders (including Desmognathus) are important in nutrient cycles in the forest ecosystem, which undoubtedly helps maintain the health of forest resources. (Bartlett and Bartlett, 2006; Bonett et al., 2007; Harding, 1997; Petranka, 1998)

Dusky salamanders can be common where habitat is intact and abundant in areas such as shaded streamsides in moist woods. But they are threatened in some areas by tree removal, which exposes the area to sun, increasing the water temperature and decreasing the humidity. Pollution of waterways can also be a serious threat. The overall effects of bait collection are unknown, but this activity may certainly impact local populations, especially if collection techniques (such as rock turning) disrupt the local habitat. (Harding, 1997; Petranka, 1998)

Desmognathus fuscus was previously considered to be made up of three subspecies: northern dusky salamanders (D. f. fuscus), spotted dusky salamanders (D. f. conanti), and Santeetlah dusky salamanders (D.f. santeetlah). However, most authorities now consider these three to be separate species: D. fuscus, D. conanti, and D. santeetlah. The range of northern dusky salamanders is as described above. Spotted dusky salamanders range from southern Illinois and western Kentucky south to the Gulf Coast. Santeetlah dusky salamanders occur only in a small geographical area high in the Unicoi, Great Smoky, and Great Balsam mountains of North Carolina and Tennessee.

The three traditional subspecies are very similar in physical appearance, with only subtle differences. D. f. santeetlah is usually the smallest and darkest. D. f. conanti is usually the most colorful, and often has 6 to 8 pairs of gold or red spots (or single lateral lines) along the back. The pattern on D. f. conanti likely comes from the juvenile character (present in all subspecies) of a wavy band and yellowish or reddish spots along the back. Desmognathus f. fuscus varies from brown or reddish brown to gray or olive, with slightly darker markings on the top and sides. The base of the tail is typically olive, yellow, or bright chestnut (a bit lighter than the body). The belly is whitish with some dark speckles (in D. f. fuscus) or lighter speckles (in D. f. conanti). The belly of D.f. santeetlah is yellowish with dark speckles. Usually there is a light stripe from the eye to the back of the mouth. (Bartlett and Bartlett, 2006; Bonett et al., 2007; Conant and Collins, 1998; Harding, 1997; Hulse, McCoy, and Censky, 2001; Petranka, 1998)

Hybridization sometimes occurs between D. fuscus and a close relative, mountain dusky salamanders (Desmognathus ochrophaeus) in Pennsylvania and Ohio. Extensive interbreeding occurs between D. fuscus and D. santeetlah where their ranges overlap in the northwestern Great Smoky Mountains. (Hulse, McCoy, and Censky, 2001; Petranka, 1998)