Plethodon cinereusEastern Red-backed Salamander(Also: Redback Salamander)

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Geographic Range

Eastern North America. The red-backed salamander's range extends west to Missouri; south to North Carolina; and north from southern Quebec and the Maritime Provinces in Canada to Minnesota (Conant 1975).

Habitat

Red-backed salamanders are terrestrial, and live in deciduous forests throughout their geographic range. They are found in the leaf litter on the ground as well as under rocks, logs, or in small burrows. They must live in a moist environment, as they lack lungs and require moist skin for respiration. One habitat factor affecting red-backed salamanders is soil pH. P. cinereus, like many other amphibians, is negatively effected by high levels of acidity. Red-backed salamanders have been shown to exhibit the same primary response to acidic substrate as do amphibian larvae exposed to acidic water, disruption of their sodium balance. The chronically lethal pH level for P. cinereus is between 3 and 4, and they are rarely found on soils with a pH of 3.7 or lower. (Frisbie and Wyman 1991, Harding and Holman 1992, Horne 1988)

Physical Description

Length: 5.7 to 12.7 cm.

The red-backed salamander has two different color phases. The "redback" phase consists of a gray or black body with a red or orange stripe down the back, extending from the neck onto the tail. The "leadback" phase lacks the red stripe, with a purely black or grey back instead. Its belly is a mottled white and gray in both phases, creating a salt and pepper pattern. Physically, P. Cinereus has 16 to 19 costal grooves, no circular constriction at the base of its tail, and it has five toes on its hind feet. These physical characteristics help to distinguish the red-backed salamander from other salamanders similar in appearance. No distinctions between males and females are noted. (Harding and Homan 1992, Conant 1975)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    0.5 g
    0.02 oz
    AnAge
  • Range length
    5.7 to 12.7 cm
    2.24 to 5.00 in
  • Average basal metabolic rate
    9.9e-05 W
    AnAge

Development

Red-backed salamanders lay eggs that develop directly into small salamanders. They do not have an aquatic larva stage, such as is found in other salamanders and most amphibians.

Lifespan/Longevity

While there is little information on lifespan in red-backed salamanders, other plethodontid salamanders can live for up to 32 years. Plethodon jordani has a mean generation time of 9.8 years, with 77% surviving to 10 years old. There is no reason to expect that red-backed salamanders can't also reach these ages. (Hairston, 1983)

  • Average lifespan
    Status: captivity
    25 years
    AnAge

Behavior

Red-backed salamanders protect their limited food supply by marking out territories. This behavior occurs most often when moisture levels are low and the salamanders have to retreat under logs or rocks. Both males and females leave scent marks on substrate as well as on fecal pellets. These chemical cues provide a great deal of information to other salamanders, including boundaries of the territorial area, size and status of the resident, and identity of the resident. In addition to the chemical information, visual cues of size and threatening displays determine what the behavior reactions of the intruder and the resident will be.

Red-backed salamanders have also shown examples of kin selection behavior. When foraging is very stressful due to dry conditions, adults holding territories will sometimes allow juveniles access to their territories. Kin can be recognized through olfactory communication, and this juvenile access is generally relegated to kin. (Horne and Jaeger 1988, Jaeger et al. 1995, Simons et al. 1997)

Communication and Perception

Red-backed Salamanders protect their limited food supply by marking out territories. This behavior occurs most often when moisture levels are low and the salamanders have to hide under logs or rocks. Both males and females leave scent marks on the ground as well as leaving their droppings. Other salamanders can learn a lot from these clues. They learn each others territorial boundaries, the size and importance of the salamanders that live in the area, and their identity, including whether or not they are related. When finding food is very hard due to dry conditions, adults who have their own territories will sometimes allow young salamanders that are related to them to use their territories. Intruders are also warned away by seeing the size of the salamander and watching it give threatening displays.

Food Habits

Red-backed salamanders feed on a large variety of invertebrates. These include mites, spiders, insects, centipedes, millipedes, beetles, snails, ants, earthworms, flies, and larvae. They forage by thrusting out their tongue in a quick, forward motion and capturing the prey. The physical environment determines food supply and foraging habits. During and shortly after rains is the optimal foraging time for P. cinereus. At these times the leaf litter on the forest floor as well as the forest vegetation is very moist. The salamanders wander throughout the leaf litter during the day and climb plants and trees at night to find prey, feeding on both ground-dwelling and arboreal invertebrates. As moisture decreases they are limited to the leaf litter, and as that subsequently dries up they eventually are restricted to areas under rocks or logs or in burrows that will continue to retain moisture. The decrease in moisture does not affect the availability of prey, but it limits the mobility of the salamanders due to their moisture requirements. Food levels are scarcer under logs or rocks and in burrows and the supply is easily exhaustible. Consequently, red-backed salamanders are pulse feeders that eat large amounts when conditions are favorable and store the extra nourishment as fat to live off of when conditions become poor. (Fraser 1976, Jaeger 1972, Jaeger 1980, Maglia 1996)

  • Primary Diet
  • carnivore
    • eats non-insect arthropods

Predation

Red-backed salamanders make up an important food source for a wide variety of snakes, birds, and mammals. They have the ability to drop all or part of their tail if under attack from a predator and can grow a new one afterwards. The tail that grows back is often lighter in color than the original tail.

Ecosystem Roles

Red-backed salamanders play an important biological role in both providing food for their predators as well as consuming large numbers of invertebrates.

Economic Importance for Humans: Positive

Red-backed salamanders may help control pest populations where they occur in high numbers.

  • Positive Impacts
  • controls pest population

Conservation Status

Red-backed salamander habitat is rather pervasive, and they are common in most of their range. In the future, however, they could be effected by high levels of soil acidity through human-induced factors such as acid rain.

Contributors

Craig Howard (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

young precocial

young are relatively well-developed when born

References

Block, Steven. 1985. Salamanders of New York. The Conservationist, March/April 1985, 39:42-47.

Conant, Roger. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Boston: Houghton Mifflin Company.

Fraser, Douglas F. 1976. Empirical evaluation of the hypothesis of food competition in salamanders of the genus Plethodon. Ecology, 57(3):459-471.

Frisbie, Malcolm Pratt, and Richard L. Wyman. 1991. The effects of soil pH on sodium balance in the red-backed salamander, Plethodon cinereus, and three other terrestrial salamanders. Physiological Zoology, 64(4):1050-1068.

Harding, James H., and J. Alan Holman. 1992. Michigan Frogs, Toads, and Salamanders: A Field Guide and Pocket Reference. East Lansing: Michigan State University.

Horne, Eva A., and Robert G. Jaeger. 1988. Territorial pheromones of female red-backed salamanders. Ethology, 78:143-152.

Jaeger, Robert G. 1972. Food as a limited resource in competition between two species of terrestrial salamanders. Ecology, 53(3):535-546.

Jaeger, Robert G. 1980. Fluctuations in prey availability and food limitation for a terrestrial salamander. Oecologia, 44:335-341.

Jaeger, Robert G., Jill A. Wicknick, Martha R. Griffis, and Carl D. Anthony. 1995. Socioecology of a terrestrial salamander: Juveniles enter adult territories during stressful foraging periods. Ecology, 76(2):533-543.

Maglia, Anne M. 1996. Ontogeny and feeding ecology of the red-backed salamander, Plethodon cinereus. Copeia, 1996(3):576-586.

Simons, Richard R., Robert G. Jaeger, and Bruce E. Felgenhaur. 1997 Competitor assessment and area defense by territorial salamanders. Copeia, 1997(1):70-76.

Hairston, N. 1983. Growth, survival, and reproduction of Plethodon jordani: trade-offs between selective pressures.. Copeia, 4: 1024-1035.