Southern Red-backed Salamander, Southern Redback Salamander
© 2011 Richard Sage (1 of 18)
Country distribution from AmphibiaWeb's database: United States
Plethodon serratus Grobman, 1944
David A. Beamer1
1. Historical versus Current Distribution. Southern red-backed salamanders (Plethodon serratus) occur in four disjunct isolates: (1) southeastern Missouri and western Illinois; (2) northwestern Georgia, eastern Alabama, eastern Tennessee, and western North Carolina; (3) central Louisiana; and (4) southeastern Oklahoma and western Arkansas (Petranka, 1998; Smith, 1998). Populations occur as high as 1,690 m (Huheey and Stupka, 1967).
2. Historical versus Current Abundance. Populations in areas where hardwood forests have been converted to intensively managed pine forests are compromised (Petranka, 1998). Highton (2003) surveyed six populations in Arkansas, Missouri, and Oklahoma prior to 1987, and again during or after 1990 and found evidence of precipitous (< 50% of original numbers) declines in five populations. Further monitoring of these populations will be necessary to determine whether these data reflect true declines or natural fluctuations.
3. Life History Features.
A. Breeding. Reproduction is terrestrial. Females in the Georgia Piedmont have spermatophores in their cloacae from February–March, while females in the southern Blue Ridge have spermatophores in their cloacae during December (Camp, 1988).
i. Breeding migrations. Undocumented, but breeding migrations are not known for any Plethodon species.
ii. Breeding habitat. Unknown.
B. Eggs. Eggs are laid in June and July (Camp, 1988; Taylor et al., 1990; Trauth et al., 1990).
i. Egg deposition sites. It is likely that eggs are deposited underground at depths of ≥ 1 m. In an experiment, two females deposited eggs when buried at a depth of 1 m, but none of the females deposited eggs when buried at 0.5 m. These females resorbed the eggs and started developing new ova for the next season (Camp, 1988).
ii. Clutch sizes. Females in Arkansas contained an average of 5.9 mature ova in one population and 7.0 in another (Taylor et al., 1990; Trauth et al., 1990). Females buried in boxes in the Georgia Piedmont each laid five eggs (4.5 mm diameter; Camp, 1988).
C. Direct Development. A clutch from the Georgia Piedmont hatched on 11 September (Camp, 1988).
i. Brood sites. It is likely that eggs are brooded underground at depths of ≥ 1 m (see "Egg deposition sites" above). In an experiment, two females deposited eggs when buried at a depth of 1 m, but none of the females deposited eggs when buried at 0.5 m . These females resorbed the eggs and started developing new ova for the next season (Camp, 1988).
ii. Parental care. Unknown, but it is likely that females brood, as with other species of Plethodon.
D. Juvenile Habitat. Juveniles likely stay at the nest site for several months after hatching. They are first found on the surface in autumn (Camp, 1988).
E. Adult Habitat. In Natchitoches Parish, Louisiana, southern red-backed salamanders are found on slopes littered with sandstone rocks and with sandy/clay soils. Dominant vegetation includes longleaf pine (Pinus palustris), yaupon (Ilex vomitoria), oaks (Quercus sp.), and a variety of forbs and grasses (Keiser and Conzelmann, 1969).
In the Great Smoky Mountains, southern red-backed salamanders are found in pine-oak or mixed hardwood forests between 457–1,686 m. Slopes having fairly dry soil seem to be preferred habitats (King, 1939; Huheey and Stupka, 1967).
In Arkansas, southern red-backed salamanders are found in leaf duff and under logs. They also are found in leaf packs along the margins of small streams (Thurow, 1957; D.A.B., personal observations).
In the Georgia Piedmont, southern red-backed salamanders are found in hilly terrain with frequent steep bluffs covered by mesic deciduous forest. In this area, they are found beneath logs and rocks and in leaf litter, stump holes, and leaf packs in hillside seeps (Camp, 1986, 1988).
F. Home Range Size. Unknown, but small home ranges are typical for Plethodon species.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. In eastern populations, southern red-backed salamanders are rarely found during the summer (Camp, 1988).
I. Seasonal Migrations. Animals migrate from forest-floor sites to underground sites in response to seasonal drying and move back into forest-floor habitats in response to favorable surface conditions.
J. Torpor (Hibernation). Southern red-backed salamanders frequently are active during the winter (Highton and Grobman, 1956; Camp, 1988).
K. Interspecific Associations/Exclusions. Southern red-backed salamanders occur together with southern zigzag salamanders (P. ventralis) at Whiteoak Sink and the Sinks on Little River in Great Smoky Mountains National Park (King, 1939; Huheey and Stupka, 1967). However, in both of the areas the 2 seem to replace each other altitudinally between 518–619 m. Southern zigzag salamanders are largely restricted to the lower elevations and southern red-backed salamanders occur at higher elevations. There is evidence of character displacement in this area, as southern zigzag salamanders are all of the unstriped phase and southern red-backed salamanders are all striped (Highton, 1972).
Following experimental exclusion studies in the Great Smoky Mountains and Balsam Mountains, Hairston (1981) concluded that there is little competition between southern red-backed salamanders and other large eastern Plethodon species.
In the Great Smoky Mountains, the following species were encountered on experimental plots with southern red-backed salamanders: black-bellied salamanders (Desmognathus quadramaculatus), seal salamanders (D. monticola), Ocoee salamanders (D. ocoee), imitator salamanders (D. imitator), pygmy salamanders (D. wrighti), Jordan's salamanders (Plethodon jordani), southern Appalachian salamanders (P. teyahalee), spring salamanders (Gyrinophilus porphyriticus), red salamanders (Pseudotriton ruber), and Blue Ridge two-lined salamanders (Eurycea wilderae; Hairston, 1980b, 1981).
In the Balsam Mountains, the following species were encountered on experimental plots with southern red-backed salamanders: black-bellied salamanders, seal salamanders, Ocoee salamanders, pygmy salamanders, southern gray-cheeked salamanders, southern Appalachian salamanders, spring salamanders, red salamanders, Blue Ridge two-lined salamanders, and eastern newts (Notophthalmus viridescens; Hairston, 1980b, 1981).
Ash (1997) reports the following salamanders along with southern Appalachian salamanders from near Highlands, Macon County, North Carolina: Ocoee salamanders, southern red-backed salamanders (P. serratus), southern gray-cheeked salamanders, and Blue Ridge two-lined salamanders (Ash, 1997).
Southern red-backed salamanders from Natchitoches and Rapides parishes, Louisiana, were found with dwarf salamanders (Eurycea quadridigitata; Keiser and Conzelmann, 1969).
In Polk County, Arkansas, southern red-backed salamanders were frequently found in wet leaf packs along the margins of small streams in May. Many-ribbed salamanders (Eurycea multiplicata) and Ouachita dusky salamanders (Desmognathus brimleyorum) were also abundant in these leaf packs. Western slimy salamanders (P. albagula) and Rich Mountain salamanders (P. ouachitae) were found in nearby terrestrial habitat (D.A.B., personal observations).
L. Age/Size at Reproductive Maturity. In populations from the Georgia Piedmont, males mature when 33–45 mm SVL, females between 33–47 mm. In populations from the Blue Ridge Mountains, adults are 33–39 m and 35–46 mm, respectively (Camp, 1988).
M. Longevity. Unknown.
N. Feeding Behavior. The following food items were found in 55 specimens (> 30 mm SVL) collected during March–April from Fulton and Harris counties, Georgia: Gastropoda, Annelida, Acarina, Araneae, Diplopoda, Chilopoda, Isopoda, Collembola, Thysanura, Isoptera, Diptera, Lepidoptera, Orthoptera, Coleoptera, Hymenoptera (ants), and unidentified larvae and adults (Camp and Bozeman, 1981).
O. Predators. Undocumented, presumably include forest mammals, birds, and snakes (Petranka, 1998).
P. Anti-Predator Mechanisms. All Plethodon produce noxious skin secretions (Brodie, 1977). Southern red-backed salamanders frequently become immobile when initially contacted. Immobility may increase survival by making the salamander less likely to be detected, especially by visually oriented predators (Dodd, 1989).
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. Southern red-backed salamander populations occur in several isolates and are listed as a Species of Special Concern in Louisiana. Within the range of most isolates, there are federal and state properties that contain suitable habitat for these salamanders.
As with all species of Plethodon, southern red-backed salamanders do not migrate to breeding grounds and they do not have large home ranges. Thus, they can exist in habitats of smaller size than many other amphibian species. Conservation activities that promote mature closed-canopy forests should benefit this species.
Acknowledgments. Thanks to Richard Highton, who reviewed this account and gave us the benefit of his insight and experience.
1David A. Beamer
2Michael J. Lannoo
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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