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Plethodon hubrichtiPeaks of Otter Salamander

By Maxwell Barney

Geographic Range

Peaks of Otter salamanders (Plethodon hubrichti) are named after the area in which they are most heavily populated, Peaks of Otter, in the Appalachian Mountains of Virginia. These three peaks are among about a 19-km stretch in the Blue Ridge Mountains in the Virginia counties of Botetourt, Rockbridge, and Bedford. (Hammerson and Mitchell, 2004; Thurow, 1957)

Habitat

Peaks of Otter salamanders are terrestrial creatures that live at elevations of 446-1067 m within their restricted range. They inhabit the floor of Appalachian hardwood forests and are often found underneath logs or rocks in moist, vegetated sections of the forest. Farallo and Miles (2016) analyzed the habitats of various members of Family Plethodontidae, and found Peaks of Otter salamanders to more likely occupy areas of slightly warmer temperatures. Overall, in comparison to similar eastern red-backed salamanders (Plethodon cinereus) and Big Levels salamanders (Plethodon sherando), Peaks of Otter salamanders are more of a generalist species when it comes to habitat selection. (Arif, et al., 2007; Farallo and Miles, 2016; Mitchell, et al., 1996)

  • Range elevation
    446 to 1067 m
    1463.25 to 3500.66 ft
  • Average elevation
    750 m
    2460.63 ft

Physical Description

Peaks of Otter salamander body lengths for adults range from 8.1 cm to 13.1 cm. The minimum snout-vent length (SVL) at sexual maturity is 39 mm for both sexes. They have a black color base, darkest on the dorsum and becoming slightly more grey around the ventral region. They become lighter at the tips of the fingers and head, appearing almost translucent with a purple tint. Stretching from the top of the head over halfway down the dorsal region into the tail, they have small clumps of gold flakes. These patches of gold flakes sometimes nearly cover the entire dorsal area. Peaks of Otter salamanders can also be albino, as one has been observed in Botetourt County.

These salamanders have a body this is a round tube-shape, slightly pressed on the anterior of the dorsum. Their skull is almost completely flat and triangular, with the eyes bulging on either corner of the flat skull. Although females have a slightly more rounded nose and a slightly larger torso compared to males, the sexes are are fairly similar. Adult males possess a mental gland on their chin, used during the breeding season.

Peaks of Otter salamanders bear a close resemblance to Cheat Mountain salamanders (Plethodon nettingi). Peaks of Otter salamanders are darker and possess more gold on the dorsal region. (Kniowski and Reichenbach, 2009; Mitchell, et al., 1996; Thurow, 1957)

  • Sexual Dimorphism
  • sexes shaped differently
  • Range length
    8.1 to 13.1 cm
    3.19 to 5.16 in

Development

Peaks of Otter salamander eggs have seldom been studied. Eggs that have been found were in a clutch size of ten eggs, each about 5 mm in diameter. Like other members of Family Plethodontidae, Peaks of Otter salamanders lay their eggs in a terrestrial environment: underneath logs, leaves, or other damp places in the soil. Plethodontid salamanders normally undergo metamorphosis before they hatch, with no aquatic larval stage. Both sexes reach sexual maturity at an SVL of 39mm.

Like other members of the genus Plethodon, these salamanders exhibit indeterminate growth. Growth continues until they reach around 10cm. At this point, growth slows. (Kniowski and Reichenbach, 2009; Marvin, 2001; Mitchell and Wicknick, 2005; Reichenbach and Sattler, 2007)

Reproduction

Peaks of Otter salamanders are monogamous during a reproductive cycle. Mating is assumed to take place underneath logs, grass, and brush in the moist areas in which they live. With Family Plethodontidae salamanders, although never formally observed in Peaks of Otter salamanders, males will "slap" (touch) the female's snout with their mental gland, expressing desire to mate via pheromones. This is followed by male excretion of a spermatophore, later to be inseminated by the female. (Jaeger, et al., 1995; Mitchell and Wicknick, 2005)

Little is known about the reproduction means of Peaks of Otter salamanders. They breed once yearly in September-October. Eggs are laid by the females about eight to nine months later at the beginning of summer, and the eggs hatch in August and into September. The young are independent upon hatching. The number of offspring ranges from 5 to 15, and time to hatching is 2 to 3 months. Average birth mass has not been published. The size at which both males and females reach sexual maturity is a snout-vent length of at least 39 mm. This size usually occurs at about 3.5 years. (Jaeger, et al., 1995; Kramer, et al., 1993; Mitchell and Wicknick, 2005; Reichenbach and Sattler, 2007)

  • Breeding interval
    Peaks of Otter salamanders breed once yearly
  • Breeding season
    Fall (September-October)
  • Range number of offspring
    5 to 15
  • Range time to hatching
    2 to 3 months
  • Average time to independence
    0 hours
  • Average age at sexual or reproductive maturity (female)
    3.5 years
  • Average age at sexual or reproductive maturity (male)
    3.5 years

Little is known about Peaks of Otter salamander parental investment, but females have been observed in attendance of nests. Males provide no parental investment beyond the act of mating. (Mitchell and Wicknick, 2005)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

Exact lifespan figures for Peaks of Otter salamanders are not known. However, a closely related species, the red-cheeked salamander (Plethodon jordani), has an average lifespan in the wild of around ten years. It is suspected that Peaks of Otter salamanders have a similar lifespan in the wild. They are not kept in captivity. (Hairston, 1983)

Behavior

Peaks of Otter salamanders, like similar salamander species, have very small home ranges. The extremely closely-related species Cheat Mountain salamander (Plethodon nettingi) will generally find a wet, damp spot underneath leaves or logs, and remain within a few meters of that spot. Peaks of Otter salamanders are thought to be aggressively territorial, protecting their territory even from members of their own species.

They are mostly nocturnal, because of the lower temperature and humidity. Peaks of Otter salamanders use pheromones via mental glands during reproduction, as well as other other communication tactics. They are not careful (compared to other members of Family Plethodontidae) when it comes to feeding, as their diet includes insects and arthropods, as well as small flowers and herbs. (Homyack and Haas, 2009; Jaeger, et al., 1995; Petranka and Murray, 2001)

  • Average territory size
    0.6 m^2

Home Range

Home range area for Peaks of Otter salamanders is about 0.6 m^2. Kramer et al. (1993) measured the median distance moved, which was 1 m. Here, we report the home range as the defended territory, due to their aggressive nature. (Dodd, Jr. and Brodie, Jr., 1976; Highton, 1999; Kramer, et al., 1993; Mitchell and Wicknick, 2005)

Communication and Perception

Not a lot is known about the communication habits of Peaks of Otter salamanders specifically, but many salamanders are known to communicate with each other via chemical signals, or pheromones. Peaks of Otter salamanders have also been known to bite eastern red-backed salamanders (Plethodon cinereus) in lab studies. Although not seen in the field, these two salamanders do occur sympatrically in the wild. Peaks of Otter salamanders possess a mental gland used for chemoreception, similar to other member of Family Plethodontidae. (Arif, et al., 2007; Dodd, Jr. and Brodie, Jr., 1976; Gibbons and Buhlmann, 2001)

Food Habits

Peaks of Otter salamanders are omnivores, as they consume small flowers and other herbaceous plants along the forest floor, as well as many arthropods and insects. In addition to small herbaceous plants, prey include worms, ants, isopods, collembolans, beetles, spiders, gastropods, lepidopteran larvae, and centipedes. Studies have shown that Peaks of Otter salamanders are opportunistic eaters. (Kramer, et al., 1993; Mitchell and Wicknick, 2005; Thurow, 1957)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • Plant Foods
  • flowers

Predation

Exact predators of Peaks of Otter salamanders are not known, but potential predators that occur sympatrically include northern ring-necked snakes (Diadophis punctatus), milk snakes (Lampropeltis triangulum), black racers (Coluber constrictor), and eastern garter snakes (Thamnopis sirtalis). Additional predators could include northern short-tailed shrews (Blarina brevicauda), southeastern shrews (Sorex longirostris), wild turkeys (Meleagris gallopavo), and brown thrashers (Toxostoma rufum).

Peaks of Otter salamanders avoid predation through a number of techniques. First, they avoid detection by becoming immobile. Their cryptic coloration presumably helps them avoid detection. Studies of intentional disturbance recorded these salamanders as remaining motionless for 1.5 seconds, up to 99 seconds. These animals also release a noxious chemical, secreted through the skin, which hinders potential predators. Finally, they also have some sort of defense posture, though it is not well-described. (Gibbons and Buhlmann, 2001; Jaeger, et al., 1995; Kramer, et al., 1993; Mitchell and Wicknick, 2005)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Peaks of Otter salamanders, similar to other Plethodon species, do not have much interaction with other species in their ecosystem. They carve out a role in the ecosystem by eating their prey, including small insects, as well as acting as a predator to animals such as snakes and shrews. No parasites have been reported for these salamanders. (Kniowski and Reichenbach, 2009; Mitchell and Wicknick, 2005; Messere and Ducey, 1998; Reichenbach and Brophy, 2017)

Economic Importance for Humans: Positive

There are no known positive economic effects of Plethodon hubrichti on humans.

Economic Importance for Humans: Negative

There are no known negative economic effects of Plethodon hubrichti on humans.

Conservation Status

The IUCN Red List status of Plethodon hubrichti is "Vulnerable," last assessed in April 2004. Peaks of Otter salamanders do not appear in the CITES appendix nor the United States Endangered Species Act list. They have no status on the State of Michigan list. The IUCN vulnerable designation is due to the species being located in fewer than five areas, although Peaks of Otter salamanders are sometimes abundant in these few areas. In addition, Peaks of Otter salamanders are a "Species of Concern" by the Virginia Department of Game and Inland Fisheries, "Federal Species At Risk" by the United States Fish and Wildlife Service, and a "Sensitive Species" by the United States National Forest Service.

Clear-cutting in the Appalachian Mountains is a possible future threat to Peaks of Otter salamanders, as clearcut sites show well fewer salamanders than at mature, wooded sites. Other potential threats include other logging activities, and even loss of canopy due to gypsy moths (Lymantria dispar).

The geographic range for Peaks of Otter salamanders, located mainly in the Jefferson National Forest, is an area that is monitored and protected. Close monitoring of the population is needed due to the limited geographic range. Currently, conservation plans are in effect in the entire geographic range of Peaks of Otter salamanders that are very restrictive on logging practices. (Hammerson and Mitchell, 2004; Mitchell and Wicknick, 2005; Mitchell, et al., 1996; Reichenbach and Sattler, 2007)

Contributors

Maxwell Barney (author), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Kioshi Lettsome (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

Arif, S., D. Adams, J. Wicknick. 2007. Bioclimatic modelling, morphology, and behaviour reveal alternative mechanisms regulating the distributions of two parapatric salamander species. Evolutionary Ecology Research, 9: 843-854.

Dodd, Jr., C., E. Brodie, Jr.. 1976. Observations on the mental hedonic gland-cluster of eastern salamanders of the genus Plethodon. Chesapeake Science, 17/2: 129-131.

Farallo, V., D. Miles. 2016. The importance of microhabitat: A comparison of two microendemic species of Plethodon to the widespread P. cinereus. Copeia, 104/1: 67-77.

Gibbons, J., K. Buhlmann. 2001. Reptiles and amphibians. Pp. 372-390 in J Dickson, ed. Wildlife of Southern Forests: Habitat and Management. Surrey, British Columbia: Hancock House Publishers.

Hairston, N. 1983. Growth, survival and reproduction of Plethodon jordani: Trade-offs between selective pressures. Copeia, 1983/4: 1024-1035.

Hammerson, G., J. Mitchell. 2004. "Plethodon hubrichti" (On-line). The IUCN Red List of Threatened Species e.T17632A7217814. Accessed September 02, 2018 at http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T17632A7217814.en.

Highton, R. 1999. Geographic protein variation and speciation in the salamanders of the Plethodon cinereus group with the description of two new species. Herpetologica, 55/1: 43-90.

Homyack, J., C. Haas. 2009. Long-term effects of experimental forest harvesting on abundance and reproductive demography of terrestrial salamanders. Biological Conservation, 142/1: 110-121.

Jaeger, R., E. Prosen, D. Adams. 2002. Character displacement and aggression in two species of terrestrial salamanders. Copeia, 2002/2: 391-401.

Jaeger, R., J. Wicknick, M. Griffis, C. Anthony. 1995. Socioecology of a terrestrial salamander: Juveniles enter adult territories during stressful foraging periods. Ecology, 76/2: 533-543.

Kniowski, A., N. Reichenbach. 2009. The ecology of the Peaks of Otter salamander (Plethodon hubrichti) in sympathy with the eastern red-backed salamander (Plethodon cinereus). Herpetological Conservation and Biology, 4/3: 285-294.

Kramer, P., N. Reichenbach, M. Hayslett, P. Sattler. 1993. Population dynamics and conservation of the Peaks of Otter salamander, Plethodon hubrichti. Journal of Herpetology, 27/4: 431-435.

Lewis, J., G. Connette, M. Deyrup, J. Carrel, R. Semlitsch. 2014. Relationship between diet and microhabitat use of red-legged salamanders (Plethodon shermani) in southwestern North Carolina. Copeia, 2014/2: 201-205.

Marvin, G. 2001. Age, growth, and long-term site fidelity in the terrestrial Plethodontid salamander Plethodon kentucki. Copeia, 2001/1: 108-117.

Messere, M., P. Ducey. 1998. Forest floor distribution of northern redback salamanders, Plethodon cinereus, in relation to canopy gaps: First year following selective logging. Forest Ecology and Management, 107/1-3: 319-324.

Mitchell, J., J. Wicknick. 2005. Plethodon hubrichti. Pp. On-line reproduction in M Lannoo, ed. Amphibian Declines: The Conservation Status of the United States Species. Berkeley, California: University of California Press.

Mitchell, J., J. Wicknick, C. Anthony. 1996. Effects of timber harvesting practices on Peaks of Otter salamander (Plethodon hubrichti) populations. Amphibian & Reptile Conservation, 1/1: 15-19.

Petranka, J., S. Murray. 2001. Effectiveness of removal sampling for determining salamander density and biomass: A case study in an Appalachian streamside community. Journal of Herpetology, 35/1: 36-44.

Reichenbach, N., T. Brophy. 2017. Natural history of the Peaks of Otter salamander (Plethodon hubrichti) along an elevational gradient. Herpetological Bulletin, 141: 7-15.

Reichenbach, N., P. Sattler. 2007. Effects of timbering on Plethodon hubrichti over twelve years. Journal of Herpetology, 41/4: 622-629.

Semlitsch, R., K. O'Donnell, F. Thompson III. 2014. Abundance, biomass production, nutrient content, and the possible role of terrestrial salamanders in Missouri Ozark forest ecosystems. Canadian Journal of Zoology, 92/12: 997-1004.

Thurow, G. 1957. A new Plethodon from Virginia. Herpetologica, 13/1: 59-66.

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