A. 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
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
Cannabilistic larval morphs exist but show geographic variation in prevalence. 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.
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.
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 ex-subspecies A. t. diaboli, A. t. mavortium, A. t. melanostictum, A. t. nebulosum, and A. t. stebbinsi. (Irschick & Shaffer 1997)
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 and London.
Written by Brian Petirs (bpetirs AT uclink4.berkeley.edu), UC Berkeley
First submitted 2001-10-30
Edited by Vance Vredenburg (2002-01-08)
Citation: AmphibiaWeb: Information on
amphibian biology and conservation. [web application]. 2013. Berkeley, California:
(Accessed: May 18, 2013).
AmphibiaWeb's policy on data use.