Northern Ravine Salamander
© 2016 Alexander Murray (1 of 14)
Plethodon electromorphus Highton, 1999
David A. Beamer1
1. Historical versus Current Distribution. Northern ravine salamanders (Plethodon electromorphus) are a cryptic species previously considered to be a part of P. richmondi (southern ravine salamanders; Highton, 1999a). Northern ravine salamanders differ from southern ravine salamanders in their protein composition and their distribution. Northern ravine salamanders range "from southwestern Pennsylvania, Ohio, and southeastern Indiana south to northwestern West Virginia, east of the New and Kanawha rivers, and northern Kentucky" (Highton, 1999a). While populations have undoubtedly been lost, the current distribution of northern ravine salamanders is likely similar to their historical distribution.
2. Historical versus Current Abundance. Unknown.
3. Life History Features. Information gathered under this scientific name likely holds for both northern ravine salamanders and southern ravine salamanders—until 1999 they shared the name “P. richmondi” and there are morphological and ecological similarities between the two species. As the older literature is sorted and a new literature is developed, it will be interesting to note whether behavioral and ecological differences between these sister species are discovered.
A. Breeding. Reproduction is terrestrial. A late winter breeding period is suggested, as a female collected in Indiana on 21 February dispelled a spermatophore while being anaesthetized (Minton, 1972, 2001). Wood (1945b) suggests that eggs are deposited from 21 April–14 May in Ohio.
i. Breeding migrations. Undocumented, but breeding migrations are not known for any Plethodon species.
ii. Breeding habitat. Unknown.
i. Egg deposition sites. A clutch of eggs presumably from a northern ravine salamander was found beneath a talus slope in Greene County, Ohio (Duellman, 1954b).
ii. Clutch size. A clutch of 12 eggs presumably from a northern ravine salamander was reported from Greene County, Ohio, on 14 July 1949 (Duellman, 1954b). Females from Ohio had from 9–15 large ovarian eggs (Wood, 1945b).
C. Direct Development. The eggs of the closely related southern ravine salamander (P. richmondi) hatched on 23 August in Kentucky. Hatchlings were 15 mm SVL (Wallace and Barbour, 1957).
i. Brood sites. Likely to be the same as egg deposition sites, but the single reported clutch of eggs did not have a female in attendance (Duellman, 1954b).
ii. Parental care. While the single clutch of eggs observed did not have a female in attendance (Duellman, 1954b), it is likely that females brood, as with other species of Plethodon.
D. Juvenile Habitat. Hatchling northern ravine salamanders remain underground, possibly at the nest site, for several months. They are first seen in the spring when they average 17 mm SVL (Pfingsten, 1989c).
E. Adult Habitat. Northern ravine salamanders have been found on forested slopes with friable soil and flat rocks. They avoid the dry crests of ridges and also stream margins and other excessively moist situations (Minton, 1972, 2001). Pfingsten (1989c) reports occasionally finding animals along the margins of streams. In Ohio, northern ravine salamanders show a strong preference for rocks and are rarely found under any other type of cover (see also Wood, 1945a; Minton, 1972, 2001). Talus slopes sometimes harbor large numbers of individuals.
F. Home Range Size. Unknown.
G. Territories. Thurow (1976) reported aggressive interactions between ravine salamanders (P. richmondi) in captivity. At this time, populations presently referred to as northern ravine salamanders were recognized as ravine salamanders (P. richmondi). It is possible that northern ravine salamanders were included in this experiment. The extent of aggressive behaviors is unknown in these salamanders. At times it may be minimal, as up to eight adults and subadults have been found beneath a single stone (Minton, 1972, 2001).
H. Aestivation/Avoiding Dessication. Northern ravine salamanders move to underground sites in response to dry surface conditions during the summer (Minton, 1972, 2001; Pfingsten, 1989c). In Ohio, they have noticeably smaller tail diameters in the fall after they emerge from aestivation (Duellman, 1954b).
I. Seasonal Migrations. Animals likely move from the forest floor to underground sites in response to seasonal cold and dry extremes, and back again as surface conditions become tolerable (Minton, 1972, 2001; Pfingsten, 1989c).
J. Torpor (Hibernation). Unknown. Lethargic individuals have been found in Ohio when temperatures were below freezing and snow was on the ground (Duellman, 1954b).
K. Interspecific Associations/Exclusions. In Indiana, northern ravine salamanders have been found with red-backed salamanders (P. cinereus), northern zigzag salamanders (P. dorsalis), and northern slimy salamanders (P. glutinosus). However, northern ravine salamanders were not found at a locality with both red-backed salamanders and northern zigzag salamanders (Minton, 1972, 2001).
In Ohio, northern ravine salamanders are associated with eastern newts (Notophthalmus viridescens), red-backed salamanders (P. cinereus), northern slimy salamanders (P. glutinosus), southern two-lined salamanders (Eurycea cirrigera), northern two-lined salamanders (E. bislineata), long-tailed salamanders (E. longicauda), northern dusky salamanders (Desmognathus fuscus), spotted salamanders (Ambystoma maculatum), Jefferson salamanders (A. jeffersonianum), and green salamanders (Aneides aeneus; Pfingsten, 1989c).
In Wooster County, Ohio, northern ravine salamanders occasionally hybridize with red-backed salamanders (P. cinereus). Ten individuals among a collection of approximately 150 specimens were morphologically intermediate between these two species. When analyzed genetically, most were more similar to red-backed salamanders, which may indicate that back-crosses to red-backed salamanders are more frequent than those to northern ravine salamanders (Highton, 1999a).
L. Age/Size at Reproductive Maturity. In Ohio, males with pigmented vasa and testes ranged in size from 38–56 mm, with an average SVL of 47.3 mm (measured to the anterior angle of the vent). Gravid females with pigmented eggs ranged from 40–57 mm SVL, with an average of 49.5 (measured to the anterior angle of the vent; Pfingsten, 1989c). The largest specimen from Ohio is a 144-mm TL female from Lawrence County (Hirschfield, 1962).
Maturity probably occurs during an animal's second summer. It is likely that females reproduce biennially (Pfingsten, 1989c).
M. Longevity. Unknown.
N. Feeding Behavior. Salamanders collected in Indiana on 23 September and 21 February contained (in approximate order of frequency) small dipteran and coleopteran larvae, ants, beetles, small spiders, earthworms, mites, and larval ticks (Minton, 1972, 2001).
The stomach contents of Ohio specimens collected at different times of the year included ants, sow bugs, earthworms, ground beetles, spiders, slugs, and land snails (Duellman, 1954b). Three adult females collected from Athens County, Ohio, in late March had eaten sow bugs, spiders, and rove beetles (Seibert and Brandon, 1960).
O. Predators. Unknown, but likely include forest snakes, birds, and small mammals.
P. Anti-Predator Mechanisms. Nocturnal. All members of the genus Plethodon produce noxious skin secretions (Brodie, 1977). The closely related southern ravine salamanders (Plethodon richmondi) 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. Northern ravine salamanders are not protected by any state. Within their range, there are many federal and state properties that contain suitable habitat for these salamanders.
As with all species of Plethodon, northern ravine salamanders 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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Citation: AmphibiaWeb. 2021. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Jan 2021.
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