View distribution map using BerkeleyMapper.

	Conservation Status (definitions)
IUCN (Red List) Status	Least Concern (LC) See threat category on the IUCN web site.
NatureServe Status	Use NatureServe Explorer to see status.
CITES	No CITES Listing
Other International Status	None
National Status	None
Regional Status	None

Description
The red-backed phase of this dimorphic species is characterized by a broad, dorsal band running down the midline from the head onto the tail. The color of the stripe varies from light gray or dull yellow to pink, brick-red, and bright red. There are often small flecks of black within the band. The sides are dark gray or black, becoming lighter and mottled toward the belly, which is strongly mottled with white and gray. The lead-backed phase is uniformly dark gray to almost black, with the head and legs usually lighter (Bishop 1943). The most logical explanation for the observed dimorphism of this species is that the gene for striping, which makes the red-backed phase, is dominant to the gene for the unicolored, unstriped condition, which makes the lead-backed phase (Highton 1959). There is also an erythristic color phase that is mostly red in order to mimic juvenile Notophthalmus viridescens (Tilley Lundrigan and Brower 1982). As all members of the genus, eggs are laid in terrestrial cavities attended by the female. The larval stage is passed within the egg capsule. Juveniles of the red-backed phase have a well developed dorsal band and the upper sides are strongly pigmented. The broad, flat, leaf-like gills rise from a common base, are often fully developed at hatching, and then persist for only a few days (Bishop 1943).

The body is long and fairly slender, is slightly flattened dorsally, and is well rounded on the sides. The cross section of the tail is nearly circular throughout its length. Regenerating tails are flattened laterally and are usually uniformly dark grey. Number of costal grooves ranges from 17 to 20, but there are usually 18 or 19. The gular fold is prominent. The legs are small with short, thick toes. There are four fingers, which in order from longest to shortest are 3-2-4-1. The five toes are slightly webbed, and are 3-4-2-5-1 in order from longest to shortest. The vomerine teeth form 2 backward-curving lines of 5-7 teeth separated from each other and from the parasphenoid teeth, which are in 2 imperfectly separated patches. The mouth is fairly large, with the angle of the jaw behind the eye. The small tongue does not fill the floor of the mouth. The fingers and toes of the juveniles are well indicated, the inner and outer short (Bishop 1943). Juveniles have proportionately broad heads, which allows them to forage on a wide range of prey (Maglia 1996).

Adult males are slightly smaller than the females, ranging from 58-91 mm in total length and averaging 73 mm. Adult females range from 64-90 mm and average 78 mm. The largest individual on record is 122 mm (Bishop 1943). Embryos average about 19 mm upon hatching and individuals less than 32 mm in snout-vent length are considered to be juveniles (Bishop 1943; Jaeger Gillette and Cooper 2002). Males can be identified when in breeding condition by swollen snout, enlarged premaxillary teeth, and proportionally longer legs (Bishop 1943). Black testes can also be seen through the abdominal wall when transiluminated by a strong light (Jaeger Gillette and Cooper 2002).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Canada, United States

U.S. state distribution from AmphibiaWeb's database: Connecticut, Illinois, Indiana, Kentucky, Massachusetts, Maryland, Maine, Michigan, Minnesota, North Carolina, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Tennessee, Virginia, Vermont, Wisconsin, West Virginia

View distribution map using BerkeleyMapper.

Plethodon cinereus ranges from the Canadian Maritime provinces and southern Quebec, west to northeastern Minnesota, and south to northern and eastern North Carolina. There is an additional isolated colony in southern North Carolina (Conant and Collins 1998). Three fourths of this range was under the last continental ice sheet 21,000 years ago, indicating that P. cinereus has the ability to rapidly disperse and has done so in recent biological history (Highton 1995). While populations from this formerly glaciated area are very uniform, allozyme studies show that when its entire range is considered, P. cinereus consists of four genetically differentiated geographic groups with within-group D-values ranging from 0-0.15 and between-group D-values ranging from 0.02-0.24. This indicates that the groups living in the unglaciated localities have been isolated from each other for 1.5-2.7 million years, and that populations from formerly glaciated areas are all descended from the same group. Despite their long divergence, there is still extensive gene flow between the groups at the points where they contact one another (Highton and Webster 1976; Highton 2000). The erythristic color phase of the species reaches its highest frequencies (20-25%) in northeastern Ohio, the Berkshire and Litchfield Hills, and the Bay of Fundy region (Tilley Lundrigan and Brower 1982). Hybridization occurs with congener P. electromorphus, which is found in southwestern Pennsylvania, Ohio, southeastern Indiana, northern Kentucky, and northwestern West Virginia.

Individuals of P. cinereus can be found beneath old logs, bark, moss, leaf mold, and stones in evergreen, mixed, and deciduous forests (Bishop 1943). P. cinereus prefers a moist environment and becomes more abundant and more active upon introduction of seeps (Grover 1998; Grover and Wilbur 2002). It also prefers a higher cover object density, which increases abundance and average body mass by making foraging more effective (Grover 1998).

Life History, Abundance, Activity, and Special Behaviors
Life History:
During the summer noncourtship season, two-thirds of individuals are found alone, while the other third lives in male-female pairs (Gillette Jaeger and Peterson 2000). Breeding takes place from October to December, during which time the pairs remain together (Bishop 1943). In the early spring, groups of 2-7 can be found together under rocks and logs (Jaeger 1979). Insemination takes place in the spring and eggs are laid in June and July (Bishop 1943; Lang and Jaeger 2000). Clutch size ranges from 3-14 eggs, usually from 8-10 (Bishop 1943; Ng and Wilbur 1995). The eggs are suspended by a common pedicel from the roof of the nest cavity, which is usually a well-rotted log (Bishop 1943). The females protect the eggs until they hatch 6-9 weeks later. Brooding females do not actively forage, but will eat opportunistically. This causes them to grow less than non-brooding females (Ng and Jaeger 1995). Females usually breed on alternate years because they normally require two years in order to store enough energy to yolk a clutch of ova and survive brooding. This is due to scarcity of prey (Jaeger Gillette and Cooper 2002).

Abundance:
Abundance of P. cinereus has been estimated as high as 2.8 individuals/m2 at Mountain Lake Biological Station in Virginia, where it probably reaches its highest density. This makes it the most abundant vertebrate species at the site, and more abundant than all birds and mammals combined (Hairston 1996; Jaeger Gillette and Cooper 2002). At the Hubbard Brook Experimental Forest in New Hampshire, the estimate for the population density of P. cinereus is 2,583 individuals/hectare, which corresponds to a biomass of 1658 grams wet wt./hectare. This biomass is approximately 2.4 times that for all birds and approximately equal to that for mice and shrews (Burton and Likens 1975). Throughout its range P. cinereus is an extermely abundant species.

Inter-Specific Behaviors:
A number of observations have been made concerning the relationship of P. cinereus with other salamander species. It is aggressive against intrusion by Eurycea cirrigera, juvenile P. glutinosis, P. hoffmani, and P. shenandoah (Jeager 1980; Jaeger Gabor and Wilbur 1998; Jaeger Prosen and Adams 2002). In the case of P. shenandoah, competition with P. cinereus has forced it onto dry talus slopes where it is in danger of extinction due to desiccation (Jaeger 1980). For other salamander species, such as Ambystoma maculatum and Desmognathus fuscus, P. cinereus is a potential prey (Ducey Schramm and Cambry 1994; Grover and Wilbur 2002). In the case of an attack by A. maculatum, 62% of P. cinereus escape and 9% are consumed (Ducey Schramm and Cambry 1994). A common response to these predation attempts is tail autonomy (Jaeger Gabor and Wilbur 1998).

Foraging Habits:
Plethodon cinereus commonly feeds on invertebrate insects found in the leaf litter, such as ants, collembola, mites, and termites (Jaeger Schwarz and Wise 1995; Lang and Jaeger 2000; Mitchell and Woolcott 1985).On rainy and foggy nights individuals can be found climbing the vegetation to forage on homopterans and hemipterans. This greatly increases volume of food ingested, but cannot be regularly undertaken because of the danger of desiccation (Jaeger 1978). When there are low prey densities, individuals have an indiscriminate diet and normally pursue prey. When there are high prey densities, individuals have a discriminate diet and normally ambush prey (Jaeger and Barnard 1981). Each individual learns through foraging experience which prey types are the most profitable. Gross caloric intake, which depends on size of the prey, and rate at which prey can be digested, which depends on the amount of chitin in the exoskeleton, are both factors that need to be considered (Jaeger and Rubin 1982). Thus, P. cinereus prefers termites to ants, because they are larger and have a softer exoskeleton (Gabor and Jaeger 1995). Overall foraging success increases with rainfall, because this makes it possible to forage out into the leaf litter (Jaeger 1980).

Intra-Specific Behaviors:
A number of intraspecific behaviors have been recorded for P. cinereus. Threatening behaviors include the all-trunk-raised (ATR) position and looking toward the opposing individual (Jaeger 1984; Jaeger Gillette and Cooper 2002). Violence can be carried out by a rapid nip with the anterior part of the mouth, which does not cause physical damage to the skin of the bitten animal, or by a full mouth hold, which may lacerate the skin (Jaeger Gillette and Cooper 2002). Bites are usually delivered to the tail or the snout in order to cause the most damage. Bites on the tail may cause tail autonomy, which involves a loss of fat reserves. Bites on the snout may damage the nasolabial grooves, thus decreasing chemoreception and causing a reduced rate of prey capture during foraging, and a reduced ability to find mates and competitors (Jaeger 1981). Submissive behaviors include the flat posture, where the whole length of the body is pressed firmly against the ground, and looking away from the opposing individual (Jaeger 1984). Tapping nasolabial cirri against the substrate is an indication of interest, because it allows chemical information to pass up the nasolabial grooves to the vomeronasal organ in the nares. The front-trunk-raised position is a resting posture (Gillette Jaeger and Peterson 2000).

These behaviors are often used to establish territoriality. Territories are used by both sexes to defend scarce prey and to avoid desiccation during rainless periods. In addition, they are used by males for courtship (Jaeger Gillette and Cooper 2002; Lang and Jaeger 2000). Territories are established under cover objects, such as rocks and logs, and can be set within 5 days by placing pheromones on the substrate (Jaeger Gillette and Cooper 2002). Scent markers are produced by the post-cloacal gland, so marking can be accomplished by touching the cloacal area to the substrate (Jaeger 1984; Simons Gelgenhauer and Jaeger 1994). Fecal pellets are also used to mark territory (Jaeger et. al. 1986). An intruder can learn characteristics of the resident male, such as size, by sampling airborne odors through gular pumping, or by touching nasolabial cirri to the fecal pellets (Jaeger 1984; Simons Jaeger and Gelgenhauer 1997).

Females are more attracted to large males, males that have a prey-rich territory, and males that do not have odors from other females (Gillette Jaeger and Peterson 2000). Females can discover how prey-rich a male's territory is by squashing his fecal pellets and seeing if it has the residue of light-armored termites or heavy armored ants (Jaeger Schwarz and Wise 1995). Since prey-rich territories are the more valuable ones, both resident and intruder males are more aggressive when the resident has eaten higher quality food (Gabor and Jaeger 1995). During an invasion of another male's territory, both the intruder and defender assume threat posture about half the time (Jaeger Kalvarsky and Shimizu 1982). Both combatants are usually in ATR prior to biting attack, but the defender exhibits the higher rate of biting and successfully defends his territory 74% of the time (Jaeger Kalvarsky and Shimizu 1982; Jaeger 1984). Larger individuals are in general better competitors, and are thus more likely to hold the prey-rich territories (Mathis 1990). Since competition is normally harmful, neighboring males exhibit dear enemy recognition, which consists of less aggression and more submissive behavior towards territorial neighbors than toward strangers (Jaeger 1981). Females that are familiar with each other also spend less time in threat displays toward each other (Jaeger and Peterson 2002).

Once a female has selected a male, the two of them form a pair and defend the territory together. In both the courtship and noncourtship seasons, males spend more time in aggression toward invading males than females do, and females spend more time in aggression toward invading females than males do. Thus, pairs can codefend a territory more successfully, but not in a cooperative manner. Their success can be seen in the fact that females spend less time intruding a territory defended by a pair than by a single individual, and that both female and male intruders spend less time on a pair's territory during courtship season than during noncourtship season. Still, the fact that the male and female of a pair cannot cooperate seems to indicate that males are not willing to pass up future polygynous relationships and females are not willing to pass up future polyandrous relationships (Lang and Jaeger 2000).

To some extent, however, the relationship between the members of a pair is monogamous. During the noncourtship season, partners show no preference to associate with each other over novel conspecifics of the opposite sex. Even during the courtship season, they show no preference toward each other over single conspecifics of the opposite sex. At this time, however, they do prefer each other over paired conspecifics of the opposite sex. During the courtship season, the male profits from the presence of the female because it increases his reproductive fitness. As a result he undertakes mate guarding. The female profits from a monogamous male because with no other female in the territory she can obtain more prey for yolking ova (Gillette Jaeger and Peterson 2000).

The male takes this monogamous relationship so far as to punish a socially polyandrous female partner, meaning one who has foraged with another male. The male can sense if his partner has associated with another male by detecting the other male's pheromones on her skin. Punishment takes the form of increased used of threat postures and even nipping if it is during the courtship season. Males also stay farther away from female partners that are socially polyandrous during both the courtship and noncourtship seasons, while they spend more time touching socially monogamous female partners. Socially polyandrous females in response show an increase in escape behavior. This sort of sexual coercion on the part of the male is logical, because he should not allow polyandrous females to feed in his territory. This might mean investing his own resources on the offspring of another male (Jaeger Gillette and Cooper 2002).

Another interesting behavior among P. cinereus is the association between juveniles and adults. Juveniles normally inhabit the leaf litter between cover objects. They are attracted by the pheromones of adults and when the leaf litter dries out and foraging becomes difficult, they enter the adults' territories. Males are less aggressive toward juveniles than toward adult males and both male and female adults are more tolerant of juveniles with which they have cohabited previously. This type of behavior seems to be some sort of kin-selection. When it rains, the juveniles return to the leaf litter (Jaeger et. al. 1995).

A final fact about P. cinereus behavior is that they seem to exhibit a certain degree of homing ability. The average daily movement of individuals is only 0.43 m/day, yet when they are displaced 30 m, 90% of them return to their territories. This return is usually along a fairly straight path and is almost immediate. When displacement increases to 90 m, only 25% of individuals return to their territories (Kleeberger and Werner 1982).

Trends and Threats
Based on observations made at Hawksbill Mountain, VA between 1966 and 1980, there appears to be no variation in the population density of P. cinereus (Jaeger 1980). The only major threat is clearcutting, which has reduced salamander populations in the southern Appalachians by almost 9%, or more than one-quarter of a billion salamanders (Alford and Richards 1999). Logging exposes terrestrial salamanders to altered microclimates, increased soil compaction and desiccation, and reduced habitat complexity.

Possible reasons for amphibian decline

Habitat modification from deforestation, or logging related activities

References
 

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