Jefferson Salamander

Ambystoma jeffersonianum
Monday, June 18, 2012

Ambystoma jeffersonianum           Compared to our familiar redback salamanders or red efts, this salamander may seem like a Gila monster. However, at 13 cm (5⅛"), it is decidedly on the small end of the range for its species. Most adults are 10.7-21 cm, with the record-holding adult being as long as the top of this sheet of paper.

           Jefferson salamanders, a species of mole salamander, are marked by a slenderer body and tail than many other types of mole salamanders. A. jeffersonianum adults have a dark brown or grey back and a paler, grayish underside. They are speckled with light bluish flecks on the sides and tail, and occasionally on the back. These are much more apparent on the younger salamanders. While they resemble slimy salamanders, Jefferson salamanders are less glossily black and lack the “slime” that gives slimy salamanders their name. Male Jefferson salamanders’ tails are more laterally compressed—that is, fin-like—than the females’. 

           In the late winter or early spring, these salamanders migrate to temporary or permanent pools in upland forests to breed. They sometimes arrive before the pools have completely thawed, as early as December-January in southern populations. There will often be many more males than females, as males breed every year while females often skip one or more years before breeding again. After mating, females will deposit hundreds of eggs in many small, gelatinous egg clusters (similar in appearance to frogs’ eggs) and attach them to underwater sticks or vegetation. Depending on when the eggs were laid and other conditions, they can hatch anywhere from 14 days to 3½ months after being laid. Although the hatching success rate is very high, the rate of survival as centimeter-long, gilled larvae is less than 1% in some populations, due mostly to predation and cannibalism. 

The larvae, like the adults, consume many varieties of invertebrates found in their habitats, as well as cannibalizing on smaller larvae or the larvae of other species. After 2-3 months in the vernal ponds, the now 4.8-7.5 cm (~2-3") larvae metamorphose into their adult form, transitioning onto land. After metamorphosing, the juveniles slowly disperse away from the pond, sometimes settling as far as a mile away. In 2-3 years, when the salamanders are mature, they will return to the same pool to mate. 

           These salamanders, unlike many in this area, have lungs and breathe air, instead of absorbing oxygen through their skin. They still, however, need to remain moist, and spend most of their time in burrows (especially rodent burrows) in deciduous forests near 250-1600 meters from their breeding pond. They hibernate in those burrows, below the frost line.

Ambystoma jeffersonianum           As a potentially tasty snack for anything from owls to snakes to raccoons, the Jefferson salamander has developed a number of defensive mechanisms. Apart from posturing, biting, flipping over, and releasing noxious fluids from the base of its tail, the Jefferson salamander has been observed to raise and thrash its tail when threatened. It is also capable of voluntarily shedding its tail. Muscle contractions in the detached tail cause it to twitch violently, diverting attention so that the salamander may escape. These salamanders have been known to live up to six years.

           Spread throughout the northeastern US (MLBS is the near the furthest southern extent of its range), Jefferson salamanders in northern populations often hybridize with three other species of mole salamanders, most often producing only triploid females. We are far enough south, however, that this salamander is almost certainly a “pure” A. jeffersonianum. This salamander was caught under a salamander tub behind the Wilbur parking lot. The somewhat irregular shape of its tail probably indicates that it has shed it at least once in the past, and it has regrown.

Hazel Galloway

See pictures of different life stages of A. jeffersonianum here, courtesy of the Virginia Herpetological Society.