Ambystoma mavortium

Geographic Range

Barred tiger salamanders ( Ambystoma mavortium ) are native to North America. Although considered common in the central and western United States, there have been sightings as far north as Canada and as far south as the U.S./Mexico border. They have been sighted as far east as Nebraska to the western coast of the U.S. The densest populations are located in Washington, southern California, Colorado and southeast Arizona.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Barred tiger salamanders inhabit a diversity of ecosystems. They have been found in bottomland deciduous forests, coniferous forests, and woodlands. They are also be found in open fields, bushy areas, alpine and subalpine meadows. They commonly use ponds as breeding grounds and sometimes streams - but only if they are slow moving. Fast streams make it harder for larvae to obtain food, thus reducing survival rates. Although barred tiger salamanders are terrestrial as adults, they live near water sources to breed and to remain cool and moist. When hibernating, they live in cool, moist burrows. These burrows can be new or pre-existing, created by salamanders or other animals. Burrow depths range from 15 to 60 cm.

• Habitat Regions
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

• Aquatic Biomes
• rivers and streams

Physical Description

Barred tiger salamanders are one of the largest salamander species, and are the largest terrestrial salamanders in North America. They grow to an average of 20.3 cm, but have been reported to grow up to about 35.6 cm and weigh an average of 126 g. Although both sexes have similar body lengths, male tails are about equal to body size; females have tails a few centimeters shorter than their body. Barred tiger salamanders have four toes that are not webbed in the front and five toes that are not webbed on their back feet. Their heads are flat and broad, with blunt noses, small eyes. They have long, thick tails. Because they are born in water, hatchlings have tail fins and gills. Juveniles at ages of one to three years develop lungs to breathe air and are able to walk on land. However, they still have a tail fin.

Adults and juveniles have a light-grey to grayish-black dorsum with scattered black or yellow dots. They also have yellow bars and lines along their body. Their colors and patterns serve as camouflage in their geographic area, so they blend in with their local habitat. There are no color differences between males and females.

Hatchlings are 13 to 17 mm long and dark yellow-green, with dark brown spots and black lateral stripes. As larvae they are 180 to 250 m long are dark yellow-green with light brown spots and black lateral stripes.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry
• poisonous poisonous

• Sexual Dimorphism
• male larger

Development

Barred tiger salamanders go through stages of metamorphosis before they become terrestrial. Juvenile salamanders are 180 to 250 mm long, have two gills, and a tail fin. It takes these larvae four to six months to become subadults. At this point, they still have a tail fin but begin to develop legs and feet. They also develop lungs to breathe air. Barred tiger salamanders remain in the pond in which they hatched until they become terrestrial and are able to walk on land. It takes an additional two to three months to become fully terrestrial. However, some juvenile salamanders may overwinter as larvae, hibernating and developing into terrestrial adults in spring. Barred tiger salamanders reach sexual maturity between the ages of four and five.

Some barred tiger salamanders are neotenic, meaning they never go through metamorphosis. They are mostly found at high altitudes in western North America. Neotenic barred tiger salamanders still have gills and remain fully aquatic as adults. They can grow up to 10 cm longer than terrestrial barred tiger salamanders. Their other basic appearances do not change.

• Development - Life Cycle
• neotenic/paedomorphic
• metamorphosis metamorphosis

Reproduction

Nothing is published on the reproductive mating systems of this species. However, as a former subspecies of tiger salamanders ( Ambystoma tingrinum ), it is likely that Ambystoma mavoritum has similar reproductive behaviors.

Males move to a pond after hibernation to prepare for the emergence of females. Breeding occurs in ponds at night. Nocturnal mating limits exposure to their natural predators. A male will nudge multiple females until one gives him attention. Once that happens, males bring an interested female away from other salamanders. Males isolate females to prevent interruptions from competitors during courtship and fertilization. Once alone, males approach females from the front, both sexes will touch noses and push each other. After this courtship, males get behind females and deposit spermatophores to fertilize eggs. Tiger salamanders are monogamous, so once males deposit their spermatophores they go back into hibernation. Female do the same after laying their eggs in ponds. Tiger salamanders may breed with old partners or new mates the following season.

• Mating System
• monogamous monogamous

Nothing is published on the reproductive mating systems of this species. However, as a former subspecies of tiger salamanders (Ambystoma tingrinum), it is likely that Ambystoma mavoritum has similar reproductive behaviors.

Barred tiger salamanders mate twice a month from mid-winter to late spring in ponds close to their burrows. Females lay between 200 and 2,000 eggs. These eggs may be laid individually or in small groups. Females attach their eggs to underwater plants, stones, or logs. Depending on the water temperature, eggs take 14 to 50 days to hatch. Warmer water temperatures help eggs hatch faster.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Nothing is published on the reproductive mating systems of this species. However, as a former subspecies of tiger salamanders (Ambystoma tingrinum), it is likely that Ambystoma mavoritum has similar reproductive behaviors.

After tiger salamander females lays their eggs, they return to their burrow. Beyond fertilization, there is no parental investment from either parent; eggs are left to survive on their own. This is why, sometimes, larvae develop into cannibal morphs or remain neotenic.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Barred tiger salamanders have a high mortality rate, living only 2 to 3 years in the wild. However, they can live 12 to 15 years in captivity.

Behavior

Barred tiger salamanders are nocturnal. As adults, barred tiger salamanders are terrestrial, but because they hatch in water, larvae are aquatic. Some larvae become cannibalistic. These annibal morphs, which are becoming more common, occur when ponds begin to dry up and food grows scarcer. As a result, salamanders have no other option but to cannibalize other larvae. Cannibal morphs are larger on average, and they more quickly develop into adults.

During winter, adult tiger salamanders burrow themselves on land to hibernate. These burrows are about 60 cm deep and are located near breeding ponds.

Male barred tiger salamanders become very aggressive during mating season. They fight other males and occasionally interrupt breeding processes.

• Key Behaviors
• fossorial fossorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• hibernation hibernation

Home Range

Barred tiger salamanders burrow themselves 3 to 17 m from their ponds. They always returns to the same pond. These salamanders does not defend territories.

Communication and Perception

Barred tiger salamanders, like other salamanders, communicate by rubbing their tails together and nudging each other with their noses. They do not have ears, but rather an opercularis muscle. This muscle allows barred tiger salamanders to sense vibrations using their forelimbs. Because barred tiger salamanders see and hunt with front facing eyes, this muscle helps detect predators that try to sneak up on them. Barred tiger salamanders do not communicate acoustically. They have nostrils to smell and detect harmful chemicals. Terrestrial barred tiger salamanders secrete a milky substance from glands on their back and tail. It is toxic if eaten.

• Communication Channels
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

The main diet of barred tiger salamanders consists of beetles, earthworms, and crickets. They have also been reported to eat other amphibians, such as frogs. These salamanders may develop into cannibalistic larval morphs that will eat other larvae and, eventually, other salamanders. Terrestrial adult barred tiger salamanders can eat mice and minnows.

These tiger salamanders have a slow metabolism, so they need to eat every two to three days.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • insectivore insectivore
  • vermivore

• Animal Foods
• amphibians
• insects
• terrestrial worms

Predation

Cannibalistic morphs play a part in the overall decline of some populations. Other common predators include raccoons ( Procyon lotor ), coatis ( Nasua narica ), and river turtles from the family ( Emydidae ). Birds and other large reptiles have also been reported to attack tiger salamanders.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Barred tiger salamander larvae have been identified as hosts for a number of parasites. Placobdella picta , a species of leech, feeds on larval salamander blood, eventually killing its host. Two species of trematodes, Telorchis corti and a species in the genus Halipegus , were found present in this species. They grow and feed on the host, causing host weakness. Chytridiomycosis, a disease caused by the chytrid fungus, is an infectious skin disease that affects a large number of amphibian species.

Economic Importance for Humans: Positive

Barred tiger salamanders are uncommonly purchased as pets, although it is illegal in most states to do so. However, hatchlings can legally be used as fish bait.

• Positive Impacts
• pet trade pet trade
• food food

Economic Importance for Humans: Negative

Cannibalistic morphs of barred tiger salamanders are known to be a nuisance to fisherman because they eat bait off of fishing hooks.

Conservation Status

No information pertaining to the barred tiger salamander is listed on the IUCN Red List, and this list does not yet recognize it as a separate species. Barred tiger salamanders are only referenced as subspecies of tiger salamanders ( Ambystoma tigrinum ). There is also no indication about their conservation status in the United States. However, in Canada they are listed as an endangered species. Their 30-year population decline is caused by extirpations at breeding sites and habitat loss. Other harmful factors include pollution and acid rain.

Since 2005 there are only 57 occupied breeding sites in British Columbia. Steps are being taken to help this species survive, such as monitoring breeding sites for non-native species and limiting human disturbance. Habitats around these breeding sites are also being protected to prevent habitat loss. Sonoran tiger salamanders ( Ambystoma mavortium stebbinsi ), a subspecies of barred tiger salamanders, is considered threatened. Cattle grazing, habitat loss, and introductions of non-native species threaten many of their populations. Members of subspecies exist in small inbred populations. No steps are currently being taken to conserve this subspecies.

Additional Links

AmphibiaWeb

Encyclopedia of Life

Contributors

Joseph Romano (author), Radford University - Fall 2015, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Cari Mcgregor (editor), Radford University, Zeb Pike (editor), Radford University, Jacob Vaught (editor), Radford University, Galen Burrell (editor), Special Projects.

References

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Bishop, S. 1943. Handbook of Salamanders . Canada: Comstock Pub Assoc.

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Colins, J. 1981. Distribution, habitats and life history variation in the tiger salamander, Ambystoma tigrinum , in east-central and southeast Arizona. Copeia , 1981/3: 666-675.

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