Description
Ambystoma mavortium is a very large salamander, among the largest known in North America. It has a broad head and a stout body. There is substantial geographic variation in color and pattern. Typically a light gray to grayish black dorsum is overlain with scattered black or dirty yellow dots or a network of yellow bars and lines. Venter varies from light to as dark as the dorsum. Hatchlings display alternating dark and light middorsal blotches and a pale lateral stripe.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Canada, United States

U.S. state distribution from AmphibiaWeb's database: Arizona, California, Colorado, Idaho, Kansas, Minnesota, Montana, North Dakota, Nebraska, New Mexico, Nevada, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, Wyoming

Canadian province distribution from AmphibiaWeb's database: Alberta, British Columbia, Manitoba, Saskatchewan

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (418 records).

A wide distribution through most of the western half of the US, only occasionally in California and Nevada. It extends from the southernmost tip of Texas up to Canada. The range has a broad north-south distribution but extends no further east than the Dakotas and Oklahoma. Populations have been introduced into southern Arizona through the human use of larvae as fish bait.

Habitat is diverse - it includes bottom land deciduous forests, coniferous forests and woodlands, open fields and bushy areas, alpine and subalpine meadow, grasslands, semideserts and deserts, and (rarely) in streams. Sandy or friable soils make for good breeding ground.

Life History, Abundance, Activity, and Special Behaviors
Breeding takes place in practically every month of the year and is environmentally influenced, especially by such factors as rainfall and elevation. Breeding takes place in both temporary and permanent locations. Eggs are deposited singly or in very small clusters.

Larva
Cannabilistic larval morphs exist but show geographic variation in prevalence. In general, larvae are predatory on other amphibian larvae and small invertebrates and vertebrates.

Trends and Threats
Declines in A. mavortium have been reported; deforestation and habitat loss in wetland and other areas are widely reported as causes. Introduction of predatory fish is not well-investigated but could potentially be an important cause of declines. Other possible causes for declines include acid-rain (Harte and Hoffman 1989), although that cause is contentious.

Relation to Humans
Often larvae are used as fish bait, thus commercial bait collectors have introduced non-native subspecies into some western regions of the US.

Comments
Ambystoma mavortium consists of a number of former subspecies of Ambystoma tigrinum. A. tigrinum now solely refers to the subspecies A. tigrinum tigrinum while A. mavortium includes the former subspecies A. t. diaboli, A. t. mavortium, A. t. melanostictum, A. t. nebulosum, and A. t. stebbinsi (Irschick & Shaffer 1997).

The species epithet, "mavortium" is a reference to the Roman god Mars, "Mavortial" or “warlike”(Tighe 2023).

This species was featured as News of the Week on 26 December 2022:

The evolution of chemical alarm cues has been puzzling to evolutionary biologists. At first glance, the cues appear to only help other individuals, not the preyed-upon individual that produced and released the cues (the 'sender'). However, according to theory, the evolution of communication systems requires benefits to senders. Releasing alarm cues can benefit the sender’s genes by warning their nearby kin, but prey often do not associate based on kinship. There is some evidence that alarm cues can protect against certain parasites and pathogens. However, an alternative hypothesis is that alarm cues attract additional predators to an attack, thereby interfering with it, and allows the prey to escape. This is known as the 'Predator Attraction Hypothesis'. Previous studies on fishes have provided support for this hypothesis, but amphibians had not been tested before. Crane et al. (2022) used Tiger salamander (Ambystoma mavortium) larvae (predators) and Wood Frog (Rana sylvatica) tadpoles (prey) to test this hypothesis and found the predators were attracted to alarm cues. This was even more apparent when the salamanders had prior experience with tadpole prey. When two salamanders were present, they rushed their attacks and were less accurate than when alone. This increased the chances of escape for tadpoles. We also found that the mere presence of visual and chemical cues from a second salamander caused enough of a distraction to increase tadpole survival. All together, their results support the Predator Attraction Hypothesis for the evolution of chemical alarm cues in tadpoles. (Written by Adam Crane)

References

Harte, J., and Hoffman, E. (1989). ''Possible effects of acid deposition on a Rocky Mountain population of the tiger salamander Ambystoma tigrinum.'' Conservation Biology, 3, 9.

Irschick, D.J. and Shaffer, H.B. (1997). ''The polytypic species revisited: Morphological differentiation among tiger salamanders (Ambystoma tigrinum) (Amphibia: Caudata).'' Herpetologica, 53(1), 30-49.

Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington D.C. and London.

Tighe, K.A. (2023). Catalog of type specimens of recent Caudata and Gymnophiona in the National Museum of Natural History, Smithsonian Institution. Smithsonian Contributions to Zoology 654.

Species Account Citation: AmphibiaWeb 2024 Ambystoma mavortium: Barred Tiger Salamander <https://amphibiaweb.org/species/5887> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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