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Plethodon vehiculumWestern Red-backed Salamander

By Rowyn Henning

Geographic Range

Habitat

The habitat of western red-backed salamanders consists of young, dense, humid, coniferous forests. It is one of the few salamanders in the Pacific Northwest to be commonly found in young forests, dwelling primarily in leaf litter, under bark, and other areas of the forest floor. Adults are commonly found beneath logs, stones, and in cool shaded areas, but they can also reside on rocky slopes. Juveniles inhabit the forest floor and make use of smaller objects such as leaves and stones for dwelling. Western red-backed salamanders can survive near streams, they prefer drier climates. They can survive in temperatures ranging from 5.0º C to 19.0º C with the most common being 10.4º C. In their habitat, they maintain a specific home region of a few square meters. (Nussbaum, et al., 1983; "Plethodon vehiculum", 2019)

  • Aquatic Biomes
  • rivers and streams
  • Range elevation
    0 to 1,250 m
    0.00 to ft

Physical Description

Western red-backed salamanders are from 42 to 58.5 mm long, depending on the sex of the salamander, as females tend to be about 3.5mm larger than the males. Their body is slender with short legs. The salamanders have gray to black sides with a gray and a venter that is speckled with iridophores (white iridescent spots). They have a dorsal stripe of either red, orange, yellow, olive or tan coloring with even edges that extends to the tip of their tail. The red variant of the dorsal stripe is most common. Some do not have dorsal stripes, but rather have the color of the stripe over their entire body. When they lack the dorsal stripe, they have varying densities of melanophores (little spots) covering the whole body, but they do not occur on the tail. Western red-backed salamanders have about 14 to 18 costal grooves and about 2.5 to 5.5 intercostal folds. The defining features between sexes are: males tend to have smaller vent lobes with a swollen lip, square-shaped snouts, and premaxillary teeth protruding from the upper lip-- while females have more rounded snouts and no swollen lobe on their vent. (Jones, et al., 2005; Nussbaum, et al., 1983)

  • Sexual Dimorphism
  • female larger
  • Average mass
    5.77 g
    0.20 oz
  • Range length
    42 to 58.5 mm
    1.65 to 2.30 in

Development

The development of western red-backed salamanders begins at the fertilization, which occurs when a male deposits a spermatophore, which is picked up by the substrate of the female. Females then lay their grape-shaped cluster of eggs every other year, during the Spring season. There is evidence to suggest that number of eggs is positive in correlation to the female's size, but there are an average of 7-11 eggs in each cluster. The mature eggs range from 4 to 5 mm in diameter. In the summer season, development of the eggs occurs, and hatchlings of the species emerge in the late summer to autumn season. Western red-backed salamanders undergo direct development, as there is no free-living larval stage and are completely metamorphosed salamanders from hatching. For the first 3 years of life, both males and females grow at a rate of about 10 mm SVL per year. In their second or third year of life, they become sexually mature. (Jones, et al., 2005; Nussbaum, et al., 1983; "Plethodon vehiculum", 2019)

Reproduction

Western red-backed salamanders mate on land, typically in a moist environment. The mating ritual is incredibly complex involving issues with mate choice, courtship rituals, and pheromone cues. (Jones, et al., 2005)

  • Breeding interval
    November - March
  • Breeding season
    Spring - Summer
  • Range number of offspring
    4 to 19
  • Average number of offspring
    11
  • Range age at sexual or reproductive maturity (female)
    2 to 3 years
  • Range age at sexual or reproductive maturity (male)
    2 to 3 years

Adult females brood over juveniles and on rare occasions, so do males. The parenting roles of western red-backed salamanders are rarely documented. (Jones, et al., 2005; "Plethodon vehiculum", 2019)

Lifespan/Longevity

  • Range lifespan
    Status: captivity
    11.1 (high) years

Behavior

Western red-backed salamanders typically remain within a home range which consists of a few square meters. They are nocturnal and have tendency to burrow. During extreme cold or hot weather they are less active above ground and will hibernate if the weather becomes too cold or partake in aestivation if the weather becomes too hot, burrowing in moist soil. Western red-backed salamanders are able to detect chemical odors from feces of nearby salamanders. While males compete for female mates, they are not territorial and adults of both sex will often share burrows/covers. However, males are more aggressive during mating season. ("Plethodon vehiculum", 2019)

  • Range territory size
    1.71 to 2.47 m^2
  • Average territory size
    2.04 m^2

Home Range

Western red-backed salamanders typically remain within a home range which consists of a few square meters. In a study in 1988, home ranges of western red-backed salamanders were determined via a mark and recapture system. The average home range of an adult male western red-backed salamander was 2.47 meters whereas for adult females it was 1.71 meters and for a juveniles it was 1.95 meters (the home range represents the mean distance between two farthest captures). (Ovaska, 1988; "Plethodon vehiculum", 2019)

Communication and Perception

Western red-backed salamanders communicate through various senses including visual, tactile, acoustic, and chemical. The visual abilities are well adapted to dim lighting due to the nocturnal nature of this species and are able to catch prey without a significant light source. Because of this, their social interactions are primarily reliant on body movement rather than color displays or patterning. Often these changes in posture act as a signaling system for nearby salamanders in situations of aggression or as a mating ritual. They also often make very low-intensity hisses, barks, clicks, squeals, and whistles to communicate with others. However, it is not currently understood how these noises function as a social behavior. Furthermore, individual salamanders release pheromones that are produced by specific glands which play a major role in recognition and complex mating rituals. Ultimately, the sense organs and nervous system of these salamanders have undergone a secondary simplification which serves as an evolutionary advantage by optimizing the senses crucial to their lifestyle. (Wells, 2007)

Food Habits

Western red-backed salamanders are carnivorous, consuming terrestrial invertebrates such as: annelids, snails, spiders, millipedes, centipedes, pseudoscorpions. They also consume insects such as flies (Diptera), moths and butterflies (Lepidoptera), bees and ants (Hymenoptera), and mites (Acari). (Nussbaum, et al., 1983; "Plethodon vehiculum", 2019)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Western red-backed salamanders have not been found to display any specific anti-predation measures, their lifestyle serves to decrease the chances of being consumed. By remaining hidden under rocks, logs and other large barriers, they prevent predators from accessing their location, successfully hiding from those who wish to eat them. Furthermore, because they are nocturnal, they face a lessened risk of being consumed. Predators include garter snakes (Thamnophis sirtalis), Steller’s Jays (Cyanocitta stelleri), shrews (Sorex species), shrew-moles (Neurotrichus gibbsii), American dippers (Cinclus mexicanus), and carabid beetles (Calleida decora). (Nussbaum, et al., 1983; "Plethodon vehiculum", 2019)

Ecosystem Roles

Western red-backed salamanders play an important role within the ecosystem by regulating the population of small invertebrates on woodland forest floors. By consuming invertebrates such as beetles, flies, ants and worms which ingest leaf matter, western red-backed salamanders promote leaf litter retention and carbon sequestering. This helps regulate the forest carbon cycle and reduce global warming. (Michelson, 2014)

Economic Importance for Humans: Positive

At this time there is no evidence of economic importance of western red-backed salamanders (Nussbaum, et al., 1983)

Economic Importance for Humans: Negative

There are no known adverse effects of western red-backed salamanders on humans. (Nussbaum, et al., 1983)

Conservation Status

While amphibian populations have decreased drastically in the last 50 years due to loss of habitat, global warming, and increased chemical contamination of ecosystems, western red-backed salamander populations remain stable. This is partially because many reside within legally protected or remote ecosystems within the Pacific Northwest and Canada. (Wells, 2007)

Other Comments

The unique scientific name Plethodon vehiculum is a result of this species mating rituals. Upon choosing a mate, the female will mount the male's tail and the two will move as a pair, the female 'riding' the male. They have been recorded transversing distances up to a meter (as noted in the 2001 study conducted by Lawrence L. C. Jones, Kristina Ovaska and Martin G. Raphael) in this fashion which is significant considering the small home range of this species. It is because of this that western red-backed salamanders have been deemed vehiculum which comes from the word 'vehicle'. (Jones, et al., 2005)

Contributors

Rowyn Henning (author), Seattle University, Gordon Miller (editor), Seattle 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

acoustic

uses sound to communicate

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

ectothermic

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

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

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

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

male parental care

parental care is carried out by males

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.

motile

having the capacity to move from one place to another.

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

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

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.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

2019. "Plethodon vehiculum" (On-line). Amphibia Web. Accessed June 05, 2019 at https://amphibiaweb.org/cgi/amphib_query?rel-common_name=like&rel-family=equals&rel-ordr=equals&rel-intro_isocc=like&rel-description=like&rel-distribution=like&rel-life_history=like&rel-trends_and_threats=like&rel-relation_to_humans=like&rel-comments=like&rel-submittedby=like&max=200&orderbyaw=Genus%2Bspecies&include_synonymies=Yes&show_photos=Yes&rel-scientific_name=contains&where-scientific_name=Plethodon+vehiculum&rel-genus=equals&where-genus=&rel-species=equals&where-species=&where-common_name=&where-clade=&where-subfamily=&where-family=any&where-ordr=any&rel-isocc=occurs+in&where-isocc=&rel-species_account=matchboolean&where-species_account=&rel-declinecauses=equals&where-declinecauses=&rel-iucn=begins+with&where-iucn=&rel-cites=equals&where-cites=&where-submittedby=.

2019. "Western Red Backed Salamander" (On-line). EOL. Accessed June 05, 2019 at https://eol.org/pages/331356.

Jones, L., K. Ovaska, M. Raphael. 2001. "Courtship Behavior of the Western Red-Backed Salamander". Northwestern Naturalist, Vol. 82, No. 3: 123-125. Accessed June 05, 2019 at https://www.jstor.org/stable/3536487?seq=1#metadata_info_tab_contents.

Jones, L., W. Leonard, D. Olsen. 2005. Amphibians of the Pacific Northwest. Seattle, WA: Seattle Audubon Society.

Michelson, M. 2014. "Salamanders' Important Role" (On-line). California Academy of the Sciences. Accessed June 05, 2019 at https://www.calacademy.org/explore-science/salamanders-important-role.

Nussbaum, R., E. Brodie, R. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. Moscow, ID: Northwest Naturalist.

Ovaska, K. 1988. "Spacing and Movements of the Salamander Plethodon vehiculum". Herpetologica, Vol. 44, No. 4: 377-386. Accessed June 05, 2019 at https://www.jstor.org/stable/3892401?seq=1#metadata_info_tab_contents.

Roth, G., U. Dicke, . Nishikawa. 1992. "How do Ontogeny, Morphology, and Physiology of Sensory Systems Constrain and Direct the Evolution of Amphibians?". The American Naturalist, 139: S105-S124. Accessed June 05, 2019 at https://www.journals.uchicago.edu/doi/abs/10.1086/285307.

Wells, K. 2007. The Ecology and Behavior of Amphibians. Chicago: University of Chicago Press.

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