© 2010 Dr. Stephen G. Tilley (1 of 23)
Country distribution from AmphibiaWeb's database: United States
Can you confirm these amateur observations of Plethodon welleri?
Plethodon welleri Walker, 1931
David A. Beamer1
1. Historical versus Current Distribution. Weller's salamanders (Plethodon welleri) inhabit high elevation regions (usually above 1,500 m, but occasionally down to about 700 m) from the Mt. Rogers and Whitetop Mountain areas of southwestern Virginia along the Unaka Mountain ridges to areas in extreme northeastern Tennessee (Johnson and Unicoi counties) and northeastern North Carolina (Yancey County), including Grandfather Mountain, North Carolina (Walker, 1934; Bishop, 1943; Hoffman, 1953; Thurow, 1956, 1964; Petranka, 1998). These populations are all associated with the Blue Ridge Physiographic Province. Populations are scattered and appear to be relictual from a previously more widespread distribution (Thurow, 1956).
2. Historical versus Current Abundance. Bishop (1943) reports that in 1938, Weller’s salamanders were abundant along the trail leading to Grandfather Mountain. In Petranka's (1998) view, the die-off of spruce-fir forests in the southern Appalachians constitutes the most obvious threat to populations of Weller's salamanders. Highton (2003) sampled Weller's salamanders from a population on the North Carolina–Tennessee border (Mitchell and Unicoi counties, respectively) and from a population in Virginia (Grayson-Smyth County) prior to 1988 and again after 1993 and found precipitous declines in both populations. Whether these data reflect true declines or natural population fluctuations can only be determined with additional monitoring.
3. Life History Features.
A. Breeding. Apparently breeding takes place in spring and fall. Males had vasa deferentia swollen with sperm in April and September and secondary sex characters show greatest development at this time (Thurow, 1963).
Organ (1960b) observed courtship of captive individuals in October. Males first become restless and begin moving. When he approaches another salamander, the tail begins to undulate laterally. The male then brings his nasolabial projections and mental gland in contact with the body of the female and advances toward her head while holding his chin against her skin. When the male reaches the female’s chin, he breaks contact and circles beneath her chin. The male then passes beneath her until his undulating tail reaches her chin. When the male’s tail reaches the female’s chin, he begins alternating vertical undulations with the lateral undulations of the tail. The female then raises her forelimb over the male’s tail and maintains a straddled position. The pair then moves forward until the spermatophore is deposited. Just prior to depositing a spermatophore, the male begins a series of lateral sacral movements while the female moves her head laterally in synchronization with but counter to the male’s movements. The male then lowers his vent to the substrate and deposits a spermatophore. The male then withdraws his tail and bends it sharply to one side. The female keeps her chin against the sharply bent tail while the pair moves forward until the vent of the female reaches the spermatophore. The female then picks up the cap from the spermatophore with her cloacal lips.
i. Breeding migrations. Undocumented, but breeding migrations are not known for any Plethodon species.
ii. Breeding habitat. Unknown.
B. Eggs. A female collected on 26 May 1997 at Grandfather Mountain deposited eggs shortly after it was placed in a container to temporarily house it for photographic purposes. It is likely that the stress of capture may have caused early deposition of the eggs, and it is unknown if females begin depositing eggs at this time naturally (D.A.B., personal observations).
i. Egg deposition sites. Nests have been found in well-rotted conifer logs under moss mats from mid August to September. Two nests are occasionally located within the same log within a few inches of one another (Hoffman and Kleinpeter, 1948; Organ, 1960b).
ii. Clutch size. In the Whitetop Mountain–Mount Rogers area, Virginia, the number of eggs range from 4–11. Eggs range in diameter from 3.6–6.5 mm and are deposited in tight clusters suspended by a stalk (Hoffman and Kleinpeter, 1948; Organ, 1960b).
C. Direct Development. As the eggs approach hatching, they enlarge slightly and become slightly ovoid. The eggs at the periphery of the mass are the first to hatch. Those that hatch first have small gill remnants and relatively little yolk. Meanwhile, those that hatch from more centrally located eggs produce smaller, less well-developed young with larger yolk supplies and larger gills. Hatchlings emerge from 12.5–15.0 mm SVL (Organ, 1960b).
i. Brood sites. Females have been found brooding eggs within well-rotted conifer logs under moss mats (Hoffman and Kleinpeter, 1948; Organ, 1960b).
ii. Parental care. Ten nests discovered in the Whitetop Mountain–Mount Rogers area each had attending females. Females guarding eggs were emaciated and had empty stomachs; it is likely that females do not feed while they are with the eggs (Hoffman and Kleinpeter, 1948; Organ, 1960b). A nest discovered within a rotting log at Grandfather Mountain, Avery County, North Carolina, had a female in attendance (D.A.B., personal observations).
D. Juvenile Habitat. Juveniles have been found in the same habitat with adults (Thurow, 1963; D.A.B., personal observations).
E. Adult Habitat. Generally found beneath logs, stones, and flakes of rock (course talus) in spruce-fir forests covering high slopes above 1,524 m (5,000 ft; Bishop, 1943; Hoffman and Kleinpeter, 1948; Organ, 1960b; Thurow, 1963, 1964). They are occasionally found at lower elevations in coves associated with limestone or in mixed deciduous forests below spruce-fir forests (Walker, 1934; Thurow, 1956; Organ, 1960b).
F. Home Range Size. Unknown, but small home ranges are typical for Plethodon species.
G. Territories. Weller’s salamanders aggressively defend territories under captive conditions. However, groups of male and female salamanders also remain closely associated with one another for long periods of time without showing aggression (Thurow, 1976).
Organ (1960b) reports that captive male Weller’s salamanders did not establish definite territories, but during September, direct contact with other males usually resulted in fighting. In October, the mere sight of another male caused an aggressive attack.
H. Aestivation/Avoiding Dessication. Weller’s salamanders are well represented in collections made during the summer (Walker, 1934; Hoffman and Kleinpeter, 1948; Thurow, 1956, 1963; Organ, 1960b).
I. Seasonal Migrations. Unknown, surface migrations are unlikely, but animals likely move from forest-floor habitats to underground sites with the seasonal onsets of cold conditions, and back to forest-floor sites with the return of favorable conditions.
J. Torpor (Hibernation). Weller’s salamanders were not found at a site on Grandfather Mountain, North Carolina, in December when temperatures were near freezing during the day and below freezing at night. This same locality harbored specimens earlier in the year (Thurow, 1963). It is likely that Weller’s salamanders move into underground retreats during colder weather.
K. Interspecific Associations/Exclusions. In the Whitetop Mountain–Mount Rogers area, the following salamander species are reported in association with Weller’s salamanders: northern gray-cheeked salamanders (P. montanus), red-backed salamanders (P. cinereus), Blue Ridge two-lined salamanders (Eurycea wilderae), Blue Ridge dusky salamanders (Desmognathus orestes), and pygmy salamanders (D. wrighti; Walker, 1934; Hoffman and Kleinpeter, 1948; Bogert, 1952). Hoffman and Kleinpeter (1948) report finding two pygmy salamanders with Weller’s salamanders on Mount Rogers at an elevation of 1,707 m (5,600 ft) in rotting logs.
Weller’s salamanders and southern ravine salamanders (P. richmondi) have both been found on Whitetop Mountain and Mount Rogers, Virginia. In this area, Weller’s salamanders appear to be restricted to high elevations and southern ravine salamanders to low elevations; the two have not been collected together (Highton, 1972).
At Limestone Cove, Unicoi County, Tennessee, Weller’s salamanders have been found with Yonahlossee salamanders (P. yonahlossee), white-spotted slimy salamanders (P. cylindraceus), eastern newts (Notophthalmus viridescens), seal salamanders (Desmognathus monticola), Carolina mountain dusky salamanders (D. carolinesis), and black-bellied dusky salamanders (D. quadramaculatus; Thurow, 1963).
At a low elevation near Carderview, Johnson County, Tennessee, Weller’s salamanders occur together with southern ravine salamanders (Highton, 1972).
On Grandfather Mountain, North Carolina, Weller’s salamanders have been found associated with northern gray-cheeked salamanders, Blue Ridge dusky salamanders, and pygmy salamanders (Walker, 1934; Thurow, 1963; D.A.B., personal observation). Near the summit of Grandfather Mountain, Weller’s salamanders, Blue Ridge dusky salamanders, and pygmy salamanders have occasionally been found sheltering beneath the same log within a few inches of one another (D.A.B., personal observation). Pope (1950) reports a Yonahlossee salamander taken on Grandfather Mountain at an elevation of 1,737 m (5,700 ft). This altitude is within the elevational range that Weller’s salamanders are known from in this area.
L. Age/Size at Reproductive Maturity. Males reach sexual maturity at about 30 mm SVL. Males probably reach breeding condition by 3 yr, though large males may breed at 2 yr of age. Females mature at about 35 mm, when they are over 3 yr old (Highton, 1962a; Thurow, 1963). The smallest female found attending a nest was 42.5 mm (Organ, 1960b).
M. Longevity. Unknown.
N. Feeding Behavior. The following food items are reported from twelve specimens collected at Grandfather Mountain, North Carolina: Chelonethida, Araneida, Acarina, Collembola, Hemiptera, Lepidoptera, Diptera, and Coleoptera. The animals had been captured 3 d prior to sacrificing them and examining their stomach contents, thus this list represents only part of the food consumed by these animals. A captive Weller’s salamander from Limestone Cove, Unicoi County, Tennessee, consumed its own shed skin. The items in the diet are found largely in the forest floor suggesting that Weller’s salamanders forage beneath the forest floor surface or beneath surface cover (Thurow, 1963).
O. Predators. Undocumented, but likely to include forest snakes, birds, and small mammals.
P. Anti-Predator Mechanisms. Weller's salamanders, as do all Plethodon (Brodie, 1977), produce noxious skin secretions. Weller's 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. Weller's salamanders are listed as a Species of Special Concern in North Carolina and as Wildlife in Need of Management in Tennessee. Weller’s salamanders are usually restricted to elevations above 1,524 m (5,000 ft) in areas with spruce-fir forest. Thus, populations are generally separated by uninhabited lower elevations. Several of these mountain peaks are on state or federal property and enjoy some degree of protection. Petranka (1998) states that die-off of spruce-fir forests constitutes a long-term environmental threat to 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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