BioKIDS home

Kids' Inquiry of Diverse Species

Four-toed Salamander

Hemidactylium scutatum

What do they look like?

The four-toed salamander is a small, lungless salamander only 5 to 10.2 cm (2 to 4 in) in length. It is a rusty brown color or gray-brown color with grayish sides. It is often speckled with black and bluish spots. Unique four-toed hind feet and a constricted ring around the base of its tail easily identify it. The tail makes up about 57 percent of its total body length (Petranka 1998).

Hatchlings are only 11 to 15 mm total body length. They are usually born with toes or toe buds. The larvae are aquatic and a yellowish brown color. A dorsal fin runs from the length of the tail to near the back of the head. Some hatchlings look more like adults but have shorter tails (Petranka 1998).

Where do they live?

Hemidactylium scutatum, the four-toed salamander, occurs from Nova Scotia to northern Minnesota, and south to the Gulf of Mexico. It has a scattered range and occurs only in small isolated populations in the southern and midwestern states. Its range is more continuous in states along the Appalachian Mountain Range, New England and west to northeastern Minnesota. (Behler and King 1979, Conant and Collins 1998, Lannoo 1998). It can be found all over Michigan except in the eastern thumb area.

What kind of habitat do they need?

Four-toed salamanders have specialized habitat requirements which require suitable breeding wetlands within or near mature forests. They prefer mature forests with dense canopy cover to preserve body moisture, lots of downed woody debris for cover and foraging opportunities, and vernal pools, ponds, bogs, shallow marshes, or other fishless bodies of water for breeding and nesting. Wooded wetlands such as swamps or swamps with lots of moss are ideal. Male adults can be located under leaves, bark, and logs in the upland forest, while females are most often found during the breeding season nesting in moss mats which overhang pools of water. (Harding 1997, Petranka 1998).

How do they grow?

How do they reproduce?

Mating occurs in the late summer, fall, and possibly into early winter in some places. The male courts the female first by rubbing his nose on the female's nose, then he will circle around her with his tail bend at a sharp right angle. At some point the female straddles the male's tail and presses her snout on the base of his tail. Eventually the male starts moving forward and begins depositing spermatophores, while the female follows him at a close distance. The spermatophores are a jelly-like glob that are about 2 mm wide at the base, and are topped with a yellowish sperm cap. The female picks up the spermatophores and deposits them into her cloaca while pressing her snout against the male's tail. This "straddle walk" lasts for up to 20 minutes (Harding 1997, Petranka 1998).

Female four-toed salamanders migrate to nesting sites primarily from the last week of March through the second week of April, but may wait until as late as early June. Oviposition occurs from mid to late April in Michigan, but can occur as early as February in southern Alabama. Females seek out moss clumps that are just above a pool of water in swamps, bogs, marshes, vernal ponds, and slow moving streams. The nesting medium is usually raised clumps of sphagnum moss, but leaf litter, rotting logs, or grass and sedge clumps are also used. The female then locates or constructs a cavity to deposit her eggs, which takes several minutes for each one and may take several hours for the whole clutch. The eggs have a sticky outer coating, which she uses to adhere to the surrounding moss. Fifteen to 80 eggs, each between 2.5 and 3.0 mm around, are laid. More eggs tend to be laid by larger females (Harding 1997, Oliver 1955, Petranka 1998). Females often share nests and as many as 1110 eggs have been found in a single nest (Blanchard 1934). Often one or more (usually one) female will stay with the nest for a period, but they are usually gone by hatching. It is believed that the mother's skin secretions may protect the eggs by stopping fungus growth. The egg incubation period varies from 38 to 62 days depending upon the region and local site conditions. Average survivorship after hatching has been estimted from 9 to 21 percent (Harding 1997, Petranka 1998).

After hatching the larva wiggle from their nest and drop into the nearby water. They are only about 1.1 to 1.4 cm total body length at birth. During this larval stage they feed primarily on tiny zooplankton and other invertebrates. Their larval period lasts between 23-39 days, which is brief compared to other amphibians. At transformation they are only 1.7 to 2.5 cm total body length (Harding 1997, Petranka 1998).

It takes between two and three years for H. scutatum to reach maturity. Captive specimens have lived as long as nine years but it is unknown how long wild individuals may survive (Harding 1997).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • Average number of offspring
    30
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    912 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    912 days
    AnAge

How long do they live?

How do they behave?

It is thought that four-toed salamanders may be slightly aggressive toward each other in defense of territories. These territories are no more than small burrows or shelters such as logs or bark.

If bothered by humans or predators, a four-toed salamander will curl up, hide its head under its tail and become still. At times they may lift their head high and sway the tail while secreting a mild but distasteful skin toxin. They can also detach their tails, which continue to wiggle, possibly distracting predators. This autotomization of their tails in unique. The tails of most salamanders must be grasped to come off (Harding 1997, Petranka 1998).

Four-toed salamanders will share breeding sites with ambystomatid salamanders ("mole salamanders") and they have been found sharing habitats with other lungless salamanders such as the red-backed salamander (Plethodon cinereus), although interactions between these species have not been observed (Easterla 1971, Petranka 1998). In late autumn, four-toed salamanders will gather with each other and other amphibians near overwintering sites. As many as two hundred individuals have been found in one site under leaf litter and inside rotting logs in November. They spend the coldest winter periods underground (Petranka 1998).

What do they eat?

Few studies have been conducted on the feeding habits of the four-toed salamander, but it is believed their diet consists mainly of insects and their larvae (beetles, flies, ants, bristletails), spiders, mites, worms, and snails (Harding 1997, Petranka 1998).

Do they cause problems?

The four-toed salamander is completely harmless to humans and their interests.

How do they interact with us?

Forest dwelling salamanders, in general, have been shown to be very important contributers to nutrient cycling and energy flow in forest ecosystems. Therefore, they are important for the health and balance of forest systems as both predator and prey. While Four-toed salamanders alone are not this abundant, it is likely that they contribute to the food web in many forests where they are plentiful.

Their diet of calcium rich invertebrates makes them nutritious meals for shrews, snakes, birds, fish, and other carnivores which likely feed on four-toed salamanders (Burton 1975b, Harding 1997).

Four-toed salamanders are harmless, slow moving, colorful creatures of our forests and wetlands and are can be an interesing find for the casual naturalist or small child.

Are they endangered?

The four-toed salamander is thought to be in a state of decline throughout its range due primarily to its specialized habitat requirements combined with destruction, degradation, and fragmentation of wetlands and forests. Even in the north and east, where the four-toed salamander's range is more continuous, it only occurs in small isolated colonies where suitable wetland-woodland habitats exist.

Hemidactylium scutatum is currently listed as endangered in Indiana and Minnesota, threatened in Illinios, and has special concern or rare status in Wisconsin, Ohio, and Missouri (Lannoo 1998). To improve conservation efforts, people should be educated on the vulnerability and value of the species.

To improve and increase habitat for the four-toed salamander, mature, closed canopy hardwood forests should be preserved. Downed woody debris should be left in place or added to these forests. Shallow vernal pools can be created within these woodlands and raised hummucks of earth can be added in and around the pool to promote growth of spagnum moss and sedges (Petranka 1998).

Individuals are likely killed crossing roads while migrating to and from breeding sites. As a preventative measure, "'critter-culverts" can be installed in areas of high road kill risk to allow salamanders to pass underneath roads to and from their breeding sites.

Some more information...

Contributors

Matthew Gates (author), Michigan State University, James Harding (editor), Michigan State University.

References

Beechy, C., R. Bruce. 1992. Lunglessness in Plethodontid salamanders is consistent witht he hypothesis of a mountain stream origin: A response to Ruben and Boucot. American Naturalist, 149(4): 839-847.

Behler, J., F. King. 1979. National Audubon Society Field Guide to North American Reptiles and Amphibians. New York, NY: Chanticleer Press and Alfred A. Knopf, Inc..

Blanchard, F. 1934. The relation of the female four-toed salamander to her nest. Copeia, 1934: 137-138.

Blanchard, F. 1935. The sex ratio in the salamander Hemidactylium scutatum (Schlegel). Copeia, 1935: 103.

Breitenbach, G. 1982. The frequency of communal nesting and solitary brooding in the salamander, Hemidactylium scutatum. Journal of Herpetology, 16(4): 341-346.

Burton, T., G. Likens. 1975b. Energy flow and nutrient cycling in salamander populations in the Hubbard Brook Experimental Forest, New Hampshire. Ecology, 56: 1068-1080.

Burton, T., G. Likens. 1975a. Salamander populations and biomass in the Hubbard Brook Experimental Forest, New Hampshire. Copeia, 1975: 541-546.

Carreno, C., T. Vess, R. Harris. 1996. An investigation of kin recognition abilities in larval four-toed salamanders, Hemidactylium scutatum (Caudata: Plethodontidae). Herpetologica, 52: 293-300.

Carreno, C., R. Harris. 1998. Lack of nest defense behavior and attendance patterns in a joint nesting salamander, Hemidactylium scutatum (Caudata: Plethodontidae). Copeia, 1998(1): 183-189.

Conant, R., J. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Third ED., Expanded. Boston and New York: Houghton Mifflin.

Easterla, D. 1971. A breeding concentration of fourt-toed slamanders, Hemidactylium scutatum, in southeastern Missouri. Journal of Herpetology, 5: 194-195.

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor, Michigan: University of Michigan Press.

Harris, R., D. Gill. 1980. Communal nesting, brooding behavior, and embryonic survival of the four-toed salamander *Hemidactylium scutatum*. Herpetologica, 36(2): 141-144.

Lannoo, M. 1998. Status and Conservation of Midwestern Amphibians. Iowa City, Iowa: University of Iowa Press.

Oliver, J. 1955. The Natural History of North American Amphibians and Reptiles. Princeton, New Jersey: D. Van Nostrand Company, Inc.

Petranka, J. 1998. Salamanders of the United States and Cananda. Washington D.C.: Smithsonian Institution Press.

Wake, D. 1966. Comparitive Osteology and Evolution of the Lungless Salamanders, Family Plethodontidae. Los Angeles, California: Anderson, Ritchie and Simon.

 
University of Michigan Museum of ZoologyNational Science Foundation

BioKIDS home  |  Questions?  |  Animal Diversity Web  |  Cybertracker Tools

Gates, M. 2002. "Hemidactylium scutatum" (On-line), Animal Diversity Web. Accessed May 24, 2017 at http://www.biokids.umich.edu/accounts/Hemidactylium_scutatum/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
Copyright © 2002-2017, The Regents of the University of Michigan. All rights reserved.

University of Michigan