Black Mountain Dusky Salamander, Black Mountain Salamander
© 2016 Alexander Murray (1 of 16)
Desmognathus welteri Barbour, 1950
J. Eric Juterbock1
1. Historical versus Current Distribution. Black Mountain salamanders (Desmognathus welteri) currently occur in the Cumberland Mountains and Cumberland Plateau in southwestern Kentucky, southern West Virginia, eastern Virginia, and north-central Tennessee (Redmond, 1980; Juterbock, 1984; Redmond and Scott, 1996; Petranka, 1998; Mitchell and Reay, 1999; Felix and Pauley, in preparation). Few data are available to allow an evaluation of present versus historical distributions. A specimen, in the West Virginia Biological Survey at Marshall University, was collected in 1938 by Neil Richmond at Blair Mountain in Logan County, West Virginia. Recent surveys in the area between this, the northernmost locality for the species, and known populations in McDowell and Wyoming counties, West Virginia, detected no new populations (Felix and Pauley, in preparation). This area has been mined extensively for coal, and it is possible that habitat degradation has resulted in the isolation of populations in the area, effectively limiting their distribution. Blair Mountain has since been mined using mountain top removal, and it is doubtful that habitat remains for the species.
2. Historical versus Current Abundance. There are no data available to properly address changes in abundance. That said, it is likely that there have been at least local decreases in the abundance of Black Mountain salamanders due to habitat alteration from the strip mining of coal and the widespread use of these salamanders as bait (see "Conservation" below).
3. Life History Features.
A. Breeding. Courtship is unknown for this species, but well known and terrestrial for other congeneric species (see accounts for D. orestes, Blue Ridge dusky salamanders, in Petranka, 1998; Tilley and Camp, this volume). Nests and larvae are associated with streams (Juterbock, 1984; Smith et al., 1996; Petranka, 1998). A gravid female 73 mm SVL was found on 30 May, with a spermatophore in her vent, indicating breeding takes place in spring. Hedonic mental glands of males are most prominent in the same populations from April to late June. Sperm wave analysis showed production of sperm occurs in summer and fall, but males appear capable of producing spermatophores throughout the active season (Felix, 2001). Data from dissections and mark-recapture suggest a biennial breeding cycle for females (Felix, 2001).
i. Breeding migrations. Unknown and unlikely. Black Mountain salamanders, as with other dusky salamanders, reproduce in their adult, stream or streamside, habitats.
ii. Breeding habitat. Usually associated with permanent, small- to medium-sized streams with moderate to steep gradients located in mesic forests (Redmond, 1980; Petranka, 1998; Felix, 2001; J.E.J., personal observations). This apparent requirement for stream permanence has been cited (Redmond, 1980) as an explanation for the species’ apparent absence from the southern Cumberland Mountains. However, a population of Black Mountain salamanders in Clay County, Kentucky, observed from 1970–'77, remained reasonably abundant and continued to reproduce in spite of the periodic absence of running water at the surface during the summer. One of us (J.E.J., personal observations) was unable to determine whether this intermittent condition was normal for that habitat or a result of road-building activity on the opposite side of the mountain. It does, however, indicate that stream permanence, short term, may not be an absolute requirement for the species.
B. Eggs. Egg clutches occur as a grape-like cluster, reminiscent of those of northern dusky salamanders (D. fuscus; Smith et al., 1996), and are guarded in nests by a brooding female. Individual eggs, averaging 4.5 mm in diameter (including capsules), are suspended by 4–12 mm long pedicles, all of which twist and attach to form the cluster. Eggs hatch in September (Juterbock, 1984; see Petranka, 1998).
i. Egg deposition sites. Smith et al. (1996) reported on four egg masses deposited in packed leaves, 5–20 cm above the water surface in the stream’s main channel. One of us (J.E.J., personal observations) has found Black Mountain salamander nests with eggs and attendant female in such situations as these, as well as under rocks on the adjacent stream bank and in the wet interstices of rocks below where the stream tumbles over surface rocks. It appears that Black Mountain salamanders, which coexist with and are often confused with northern dusky and seal salamanders (D. monticola), broadly overlap these two species in nesting requirements.
ii. Clutch sizes. The number of eggs in four clutches averaged 26 (range = 18–33; Smith et al., 1996).
i. Length of larval stage. The larval period is apparently 20–24 mo (Juterbock, 1984). Hatchling larvae have been found in September, ranging in size from 11–12.5 mm SVL. At this time of year, there are two size classes of Black Mountain salamander larvae, with the larger cohort representing animals from the preceding summer. By this time, sympatric larval northern dusky and seal salamanders from the previous summer had undergone metamorphosis. Similar evidence suggests a 2-yr larval period in the northern portion of the species’ range (McCleary, 1989; Felix, 2001).
ii. Larval requirements.
a. Food. Unknown.
b. Cover. One of us (J.E.J., personal observations) has typically observed small larvae among sand and gravel and leaf litter in shallow (usually ≤ 3 cm) water, usually out of the current. Larger larvae are found here or in deeper water (usually ≤ 10 cm) without much current and often associated with slightly larger stones. Larvae often are not seen in the middle of pools.
iii. Larval polymorphisms. Unknown and unlikely.
v. Post-metamorphic migrations. Unknown and unlikely.
vi. Neoteny. Unknown and unlikely.
D. Juvenile Habitat. Juveniles are found associated with the same habitats as the adults: permanent, small- to medium-sized streams with moderate to steep gradients located in mesic forests (Redmond, 1980; Petranka, 1998; J.E.J., personal observations). Differences in micro-scale distribution between adults and juveniles remain unstudied, but juveniles and adults may partition microhabitats along streams in terms of distance to the land/water interface. While it appears to one of us (J.E.J.) that juveniles are more terrestrial than adults, in other populations, juveniles were found substantially farther into streams than adults (Felix and Pauley, 2001). It is possible adults exclude juveniles from the land/water interface, and that in the population studied by Felix and Pauley (2001), juveniles move into the water to avoid competition or predation from more terrestrial seal and northern dusky salamanders. Because the cannibalistic (both intra- and interspecific) tendencies of congeneric black-bellied salamanders (D. quadramaculatus) are well known (see Petranka, 1998) and size dependent, a difference in microhabitat preferences between adult and juvenile Black Mountain salamanders would not be unexpected.
E. Adult Habitat. Adults are found along permanent, small- to medium-sized streams with moderate to steep gradients located in mesic forests at elevations from 300–800 m (Redmond, 1980; Petranka, 1998; Felix, 2001; J.E.J., personal observations). Adults frequently are associated with large rocks (Petranka, 1998). Although generally aquatic, individuals are also commonly found on the stream banks (J.E.J., personal observations). Sexual dimorphism in habitat characteristics is unknown.
F. Home Range Size. Limited data suggest Black Mountain salamander movement patterns and home range size are similar to other Desmognathus species (see Petranka, 1998). Measurements from 18 recaptures of 12 salamanders show individuals moved an average of 1.8 m, with the longest distance moved 7.5 m. Individuals recaptured multiple times showed an association with structures such as cascades or mid-stream gravel bars (Felix, 2001).
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Aestivation is unknown. Allegheny Mountain salamanders are found adjacent to stream banks, which may buffer them from the effects of dessicating conditions.
I. Seasonal Migrations. Unknown and unlikely.
J. Torpor (Hibernation). Unknown.
K. Interspecific Associations/Exclusions. Syntopic with northern dusky salamanders and seal salamanders throughout their range, and with Allegheny Mountain dusky salamanders (D. ochrophaeus) in portions of their range. In southern West Virginia, Black Mountain salamanders occur sympatrically with three congeners in communities similar to those described by Bruce (1991) and others. Allegheny Mountain salamanders reside in forests adjacent to stream banks. Within the streambed, Black Mountain salamanders represent the large-bodied, aquatic species, followed by seal and northern dusky salamanders in order of increasing terrestrial tendency (Felix and Pauley, 2001). It has been suggested that Black Mountain salamanders are excluded from some streams through competition with morphologically and ecologically similar black-bellied salamanders (Seeman, 1996).
L. Age/Size at Reproductive Maturity. Maturity is estimated to be at 4–5-yr old and at 50–55 mm SVL (Petranka, 1998). As one of us has discussed (Juterbock, 1978, p. 225), it is not clear how “effective sexual maturity” relates to the non-synchronous appearance of secondary sexual characteristics in male dusky salamanders. By the time they reach 50 mm SVL, virtually all male Black Mountain salamanders exhibit the adult condition for most secondary sexual traits and are presumably mature. The smallest male examined by Felix (2001) with mature sperm was 50 mm SVL. Females typically are found with yolked ovarian ova at the same size (Juterbock, 1978). With a 20–24-mo larval period, this is a minimum of 4 yr to maturity.
M. Longevity. Individuals can live at least 20 yr in captivity (Snider and Bowler, 1992).
N. Feeding Behavior. The five most numerically important prey groups in West Virginia specimens were adult dipterans, coleopterans, winged hymenopterans, larval dipterans, and larval lepidopterans. Four of these groups are terrestrial in origin, suggesting Black Mountain salamanders forage mainly out of water and capture both aerial and ground-dwelling insects. No remains of salamanders were observed in stomachs. The diet of Black Mountain salamanders is similar to sympatric seal salamanders, differing mostly in that the former consumed more aquatic prey (Felix and Pauley, in preparation). Captive individuals readily eat earthworms (J.E.J., personal observations).
O. Predators. Unknown.
P. Anti-Predator Mechanisms. Unknown, but presumably similar to the aggressive defense described for other dusky salamander species (Brodie, 1978). In the laboratory, black-bellied salamanders oriented their heads toward approaching short-tailed shrews (Blarina brevicauda), even if that required flipping their bodies around. This was accompanied by an open-mouth display. If the predator continued approaching, the salamander lunged toward it, loudly snapping the mouth closed. If bitten by the predator, they bit back, normally holding on (up to 47 s in one case) and sometimes twisting, especially if they bit the predator’s snout. This defense kept four of five alive for 3–7.5 min, in a situation where escape was impossible. Smaller seal and Allegheny Mountain dusky salamanders were less successful, but similarly defended themselves. Northern dusky salamanders also bite, apparently in defense (Noble, 1954; J.E.J., personal observations); Noble also notes that when grasped, they are very likely to “twist strenuously.” Both behaviors have been observed in Black Mountain salamanders (J.E.J., personal observations).
Q. Diseases. Unknown.
R. Parasites. Intestinal parasites from West Virginia specimens were identified by J. Joy of Marshall University as the nematode Batracholandros magnavulvaris. This parasite has been reported from other species of Desmognathus salamanders (Joy et al., 1993).
4. Conservation. Redmond (1980) indicates that both habitat alteration from the strip mining of coal and the widespread use of these salamanders as bait have led to local population declines in Black Mountain salamanders. During the 1970s, after the 1973 oil embargo revitalized the coal industry in this region, one of us (J.E.J., unpublished data) observed two kinds of negative mining effects on Black Mountain salamander populations. Siltation increased dramatically downstream of mining activity,which appeared to at least alter the micro-distribution of larvae, if not their abundance; mountain top removal, with the resultant deposition of the overburden in the valley below, completely eliminated salamander habitat. Black Mountain salamanders are now listed as Rare in West Virginia.
1J. Eric Juterbock
2Zachary I. Felix
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Jan 2017.
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