Allegheny Mountain Dusky Salamander
© 2000 John White (1 of 18)
Country distribution from AmphibiaWeb's database: United States
Desmognathus ochrophaeus Cope, 1859
Thomas K. Pauley1
1. Historical versus Current Distribution. Dunn (1926) described the range of Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus) from Clinton County, New York, south to Garrett County, Maryland, and west to Columbus, Ohio, through the Appalachian Plateau of Pennsylvania. Bishop (1941b) extended the range south to Highland County, Virginia. Bishop (1943) further extended the range west into eastern Kentucky, and south through West Virginia, southwestern Virginia, western North Carolina, eastern Tennessee, and into northern Georgia. Sharbel and Bonin (1992) described the northernmost point of the range of Allegheny Mountain dusky salamanders at the Chateauguay River drainage in Québec, Canada. Recent descriptions of several sibling species based upon geographic and molecular data have reduced the southern range of Allegheny Mountain dusky salamanders to the southern mountains of Tennessee (Tilley and Mahoney, 1996). Tilley and Mahoney (1996) determined that the range of Allegheny Mountain dusky salamanders extends from southwestern Virginia (Burmley, Clinch, Walker, and Potts mountains) west into the Cumberland Mountains and Cumberland Plateau of southeastern Kentucky, north through the Allegheny Plateau and Allegheny Mountains of West Virginia, Maryland, Pennsylvania, Ohio, and through the Adirondack Mountains in New York into southern Québec. While populations have undoubtedly been lost, there are no data to support recent range reductions.
2. Historical versus Current Abundance. In the higher elevations of West Virginia (975–1,463 m), Pauley (1980a) found Allegheny Mountain dusky salamanders in forested habitats on 17 of 19 mountains surveyed from 1976–'79. Of the five most common species observed, Allegheny Mountain dusky salamanders comprised 26.5% of the salamander assemblage. In this study, while Allegheny Mountain dusky salamanders ranged from 975–1,400 m, they were most abundant between 975 and 1,036 m.
Petranka et al. (1994) demonstrated that local populations of the sibling species Blue Ridge dusky salamanders (D. orestes) can be severely impacted by clearcutting. Pauley (unpublished data) found Allegheny Mountain dusky salamanders are slower than eastern red-backed salamanders (Plethodon cinereus) to recolonize early successional forests in clearcut areas in northern West Virginia. Pauley (1980b) found that Allegheny Mountain dusky salamanders require cooler and more moist areas for foraging and nesting sites than do eastern red-backed salamanders. The inability of Allegheny Mountain dusky salamanders to recolonize clearcuts may be due to the lack of optimal foraging and nesting sites in young regrowth forests.
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Allegheny Mountain dusky salamanders do not migrate.
ii. Breeding habitat. Allegheny Mountain dusky salamanders occupy moist areas such as first-order streams, spring seeps, and wet rock faces. As with most plethodontids, courtship and mating occur at night. Barbour (1971) observed a pair in a courtship dance in Harlan County, Kentucky, on 14 July. Bishop and Crisp (1933) reported finding a spermatophore in the cloacal vent of a female from New York in May. Tactile and chemical stimulation are used by males during courtship (Verrell and Mabry, 2000).
i. Egg deposition sites. Nesting areas are usually under moist fallen logs, under rocks, and in mud banks. Nests have been found under rocks ≤ 0.5 m from a water source (Pauley, 1993b) and in interstices within seepage banks of first-order streams (Keen and Orr, 1980; Marcum, 1994).
Eggs are deposited in grape-like clusters, and each egg is attached to a central stalk (Bishop and Crisp, 1933; Bishop, 1941b). Keen and Orr (1980) found spent females in northern Ohio populations in late April. The clutch size in Allegheny Mountain dusky salamanders corresponds to female body size, with larger females producing larger clutches (Keen and Orr, 1980).
ii. Clutch size. Pfingsten (1966) found clutch sizes numbering around 19 eggs in Ohio. Wood and Wood (1955) reported 10–37 eggs/clutch in Virginia. Green and Pauley (1987) reported clutch sizes around 19 in West Virginia, although Marcum (1994) reported smaller clutch sizes in West Virginia, ranging from 3–19. In Pennsylvania, clutch size ranges from 8–24 (Hall, 1977). Allegheny Mountain dusky salamander females are able to recognize and brood eggs from related individuals (Masters and Forester, 1995).
Bishop and Crisp (1933) found freshly laid eggs in August and newly hatched larvae in September and March in New York and northern Pennsylvania. Marcum (1994) determined that eggs hatch in northern West Virginia in early October. The average SVL of young at hatching is 8.7 mm. Keen and Orr (1980) noted that larvae emerged from a clutch of eggs on 19 April in Ashtabula County, Ohio. In Kentucky, eggs are deposited in August, September, and October, and larvae are about 2 cm (3/4 in) long (Barbour, 1971). Bishop (1941b) observed hatching in a New York population in mid March. The timing of hatching varies with elevation and may be biphasic. Eggs and recently hatched young have been observed during autumn and spring (Bishop, 1943; Keen and Orr, 1980; Marcum, 1994).
C. Larvae/Metamorphosis. The larval period of Allegheny Mountain dusky salamanders varies depending on moisture and temperature (Bishop, 1941b). Gills may be lost in several days to several weeks or up to 8–10 mo, depending on temperature and food availability (Bishop, 1941b). Allegheny Mountain dusky salamanders from northern West Virginia may have larval periods of only 1–3 wk. Marcum (1994) found transformed juveniles that still showed signs of yolk plug remnants and also observed transformed individuals with considerable amounts of yolk present. Allegheny Mountain dusky salamander larvae were not found in the same streams during a 5-yr study prior to Marcum’s work (Pauley, 1995a). Bishop and Crisp (1933) suggested that larvae transformed at a length of 18 mm without entering water.
i. Food. Orr and Maple (1978) found that Allegheny Mountain dusky salamander larvae used their yolk sacs by 140 d after hatching. Several reports indicate that the larval period is short and in some cases may only occur in the egg (Bishop, 1943; Marcum, 1994). Marcum (1994) found newly transformed individuals with yolk plugs or traces of yolk plugs that could supply them with sufficient nutrients until they completely transformed.
D. Juvenile Habitat. The juvenile habitats of Allegheny Mountain dusky salamanders are similar to those of adults. Although juveniles can be found under the same types of cover objects as the adults and in the same habitat, they are observed more frequently under and between damp leaves on the forest floor and at the edges of first-order streams. Smaller individuals may utilize smaller cover objects and may be found at greater distances from low elevation streams, where larger congenerics are absent.
E. Adult Habitat. Allegheny Mountain dusky salamanders occupy moist woodlands, seepage areas, wet rock faces, and small streams throughout most of their range (Keen, 1979; Green and Pauley, 1987). These salamanders are found under rocks, leaves, bark, and logs and can be found in forests some distance upslope from streams (Weber, 1928; Green and Pauley, 1987; Pauley, 1995a). In a 5-yr study of salamander composition along two, 100-m, horizontal transects located 20 m and 40 m upslope of first-order streams in four watersheds in northern West Virginia, Allegheny Mountain dusky salamanders (n = 1,787) outnumbered the typically more terrestrial eastern red-backed salamanders (n = 855) 2:1 (Pauley, 1995a). This result demonstrates that Allegheny Mountain dusky salamanders can be abundant in moist ravines, moist old logging roads, and close to seepages.
F. Home Range Size. The average home range of Allegheny Mountain dusky salamanders from Ohio populations is < 1 m2 (Holomuzki, 1982). Holomuzki (1982) found that some Allegheny Mountain dusky salamanders return to their home territory when displaced ≤ 30 m. In Pennsylvania, Hall (1977) found the average movement of Allegheny Mountain dusky salamanders to be 1.8 m.
G. Territories. Smith and Pough (1994) observed that when compared to eastern red-backed salamanders, Allegheny Mountain dusky salamanders were more successful defending their territories and intruding into other territories. Stewart and Bellis (1970) found that Allegheny Mountain dusky salamanders were arranged randomly along a stream bank and that disturbing the cover objects caused salamanders to disperse to other cover within 1–2 d. Individuals from West Virginia have been found sharing cover objects such as rocks and logs with up to three or more conspecifics (personal observations).
Evans et al. (1997) showed that female Allegheny Mountain dusky salamanders exhibited a significant preference for substrates that were marked with scents from males outside their population. Evans and Forester (1996) suggest that male Allegheny Mountain dusky salamanders use chemical clues to identify potential rivals in their territory, but chemical clues may be less important for female recognition of other female conspecifics. Geographic proximity may be important in recognition of conspecifics for courtship. Electrophoretic data demonstrated low levels of hybridization between Allegheny Mountain dusky salamanders with northern dusky salamanders (D. fuscus) in Québec (Sharbel et al., 1995).
H. Aestivation/Avoiding Dessication. Allegheny Mountain dusky salamanders are active on the surface from March–October in Ohio and southern and northern West Virginia (Keen, 1979; Pauley, 1993b, 1995a). Locomotion and foraging are affected if a dehydration deficit exceeds 12% (Houck and Bellis, 1972).
I. Seasonal Migrations. Seasonal migrations of Allegheny Mountain dusky salamanders have been reported. Allegheny Mountain dusky salamanders will move from the surface to underground refugia with the onset of cold weather.
J. Torpor (Hibernation). Allegheny Mountain dusky salamanders apparently emerge from winter refugia in late March and April and remain active on the forest floor through October (Keen, 1979; Pauley, 1993b, 1995a). They are less active on the surface and ingest less prey when air temperatures drop from 5–0 ˚C, and they remain in underground refugia when temperatures drop below 0 ˚C (Keen, 1979). They will remain active during the winter around springs, seepages, and bogs or fens (Green and Pauley, 1987).
K. Interspecific Associations/Exclusions. Over a large portion of their range, Allegheny Mountain dusky salamanders are associated with three other desmognathine salamanders: black-bellied salamanders (D. quadramaculatus), seal salamanders (D. monticola), and northern dusky salamanders. These four species make up an assemblage within the mountain streams where they are found. In northern Ohio, Allegheny Mountain dusky salamanders are sympatric with northern dusky salamanders (Orr and Maple, 1978). At higher elevations and more northern latitudes, Allegheny Mountain dusky salamanders occupy more terrestrial habitats and can be found at considerable distances from the nearest water source. At high elevations in West Virginia, Allegheny Mountain dusky salamanders are sympatric with eastern red-backed salamanders, northern slimy salamanders (P. glutinosus), Wehrle's salamanders (P. wehrlei), and Cheat Mountain salamanders (P. nettingi; Santiago, 1999).
L. Age/Size at Reproductive Maturity. Bishop (1943) lists the length of males from Rochester, New York, at over 70 mm and females at 73 mm. Orr (1989) reports adult males from Ohio to be 37 mm SVL. Hall (1977) found males mature at 3 yr. Females from northern Ohio yolked their first clutches of eggs at around 27–30 mm SVL and at approximately 36 mo of age (Keen and Orr, 1980). Keen and Orr (1980) note that some females from Ohio do not complete their first clutch of eggs until 36–42 mo.
M. Longevity. Snider and Bowler (1992) report that a captive Allegheny Mountain dusky salamander lived for nearly 20 yr. It is not known if this specimen was truly D. ochrophaeus or a sibling species.
N. Feeding Behavior. Juvenile and adult Allegheny Mountain dusky salamanders, similar to other Desmognathus species, are ambush predators. Adult and larval dipterans, hymenopterans, snails, mites, earthworms, and collembolans are important food items for Allegheny Mountain dusky salamanders (Krzysik, 1979; Keen, 1979; Pauley, 1995a). Keen (1979) observed that temperature alters feeding activity of Allegheny Mountain dusky salamanders. Salamanders in seepage habitats were more active at lower temperatures than in streamside habitats, and foraging success was closely correlated with precipitation. They are most active around sunset and during the first hour thereafter when prey items (especially dipterans) become active (Holomuzki, 1980). Fitzpatrick (1973) found that female Allegheny Mountain dusky salamanders need only 2,940 cal/yr to survive and reproduce.
O. Predators. Female Allegheny Mountain dusky salamanders have been reported to prey upon conspecific eggs, larvae, and hatchlings (Fitzpatrick, 1973; Wood and Wood, 1955). Undoubtedly, Allegheny Mountain dusky salamander eggs and larvae serve as prey for larger streamside salamanders, such as other species of Desmognathus, and adults, juveniles, and larger larvae of Eurycea and Gyrinophilus.
Juveniles and adult predators include garter snakes (Thamnophis s. sirtalis; Whiteman and Wissinger, 1991) and birds (Coker, 1931). Other predators probably include ring-necked snakes (Diadophis punctatus), small rodents, and other mammals, and turkeys and other birds. Ring-necked snakes may be less of a threat because Allegheny Mountain dusky salamanders are known to avoid substrates that ring-necked snakes have marked with their scent (Cupp, 1994).
P. Anti-Predator Mechanisms.
i. Eggs. The most effective anti-predator mechanisms are probably cryptic sites for nests and maternal care of the eggs.
ii. Larvae. Little is known of the anti-predator mechanism of Allegheny Mountain dusky salamander larvae. As some populations have short larval stages, anti-predator mechanisms are probably similar to those of the eggs—cryptic sites with maternal brooding.
iii. Adults. Lutterschmidt et al. (1994) demonstrated that Allegheny Mountain dusky salamanders avoid skin extracts from conspecific and heterospecific salamanders. This suggests that Allegheny Mountain dusky salamanders respond to chemical signals from damaged salamander skin, and these chemicals may be important in predator avoidance. Brodie (1977) lists members of the genus Desmognathus as using biting and pseudoaposematic coloration as anti-predator defenses. Whiteman and Wissinger (1991) similarly report biting and tail autotomy as important anti-predator behaviors in response to garter snake attacks, although they suggest tail autotomy may be most important, especially in regard to larger snakes. Brodie and Howard (1973) suggested that Allegheny Mountain dusky salamanders resemble several species of Plethodon, including eastern red-backed salamanders and Cheat Mountain salamanders, and that Allegheny Mountain dusky salamanders may be a polymorphic Batesian mimic of these Plethodon species. Dodd et al. (1974) found that when predators were fed one Plethodon species (Peaks of Otter salamanders, P. hubrichti), they experienced what was interpreted as discomfort. The dorsal coloration of Allegheny Mountain salamanders within the range of eastern red-backed salamanders and Cheat Mountain salamanders in West Virginia varies from a red dorsal stripe to dark backs (T.K.P., personal observations). These dorsal patterns could be an effective mimic of these two potentially distasteful species of Plethodon.
Q. Diseases. There are no reports of diseases in Allegheny Mountain dusky salamanders.
R. Parasites. Rankin (1937) found the protozoans Prowazekella longifilis and Tritrichomonas augusta, and the nematode Capillaria augusta. Baker (1987) lists three nematode parasites of Allegheny Mountain dusky salamanders: Batracholandros salamandrae, B. magnavulvaris, and Falcaustra plethodontis. Goater et al. (1987) lists adult nematodes (Capillaria inequalis, Thelandros magnavulvaris, Omeia papillocauda, Falacustra plethodontis, Cosmoceroides dukae), trematodes (Brachycoelium elongatum, Gorgoderina bilobata, Phyllodistomum solidum), and cestodes (Cylindrotaenia americana) in Allegheny Mountain dusky salamanders. Goater et al. (1987) also found larval nematodes (Ascaridoidea sp.), cestodes (Proteocephalan plerocercoid), and acanthocephala (Centrorynchus conspectus) in Allegheny Mountain dusky salamanders.
4. Conservation. Allegheny Mountain dusky salamanders are common terrestrial and semi-aquatic salamanders in the central and northern Appalachian Mountains. They occupy a variety of forested habitats and appear to survive silvicultural impacts and forest fragmentation. Isolated mountain populations in eastern Kentucky and Tennessee should be monitored more closely (Petranka, 1998). This may be particularly true for those populations that could be impacted by mountain top removal coal mining.
1Thomas K. Pauley
2Mark B. Watson
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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