Ambystoma tigrinum

Coloration geographically variable to an extreme, often mottled, blotched, or spotted; adults are stocky, with 11-14 (usually 12-13) costal grooves, a broad head, small eyes, and tubercles on the soles of the feet; pond-type larva (but lacks balancers), with three large pairs of gills, vomerine teeth in U-shaped pattern, and dorsal fin extending to region of axilla; adults usually are about 15-22 cm in total length (to about 34 cm) (Stebbins 1951, 1985; Behler and King 1979; Conant and Collins 1991).

The following pertains to metamorphosed adults. Differs from A. MACRODACTYLUM in lacking a distinct dorsal stripe or stripelike row of spots. Differs from A. GRACILE in having distinct dorsal markings and tubercles on the underside of the feet and by lacking parotoid glands and a glandular ridge on the tail. Differs from A. ANNULATUM in lacking a light grayish stripe along the lower side of the body and generally lacking narrow light bands across the body. Differs from A. MACULATUM and A. OPACUM in having large light blotches on the sides. Differs from A. TALPOIDEUM in having sharply defined spots and usually more than 11 costal grooves (vs. 10-11). Differs from all other North American AMBYSTOMA in having tubercles on the soles of the feet. Differs from plethodontid salamanders in lacking a nasolabial groove.

Tiger salamanders can be found in virtually any habitat, providing there is a terrestrial substrate suitable for burrowing and a body of water nearby suitable for breeding. Terrestrial adults usually are underground, in self-made burrows or in those made by rodents, shrews, or other animals. In New York, adults on land used wooded areas and avoided grassy areas (Madison and Farrand 1998). At high elevations in the Rocky Mountains, metamorphosed adults commonly occur in ponds throughout the summer. Breeding occurs in a wide range of environments, ranging from clear mountain ponds to temporary, manure-polluted pools in the lowlands, generally in sites where predatory fishes are absent. In the mountains of western Colorado, tiger salamanders are associated with ponds that have silty bottoms, low alkalinity, and no fishes (Geraghty and Willey 1992). In the southeastern U.S., this species breeds in open, grassy, usually temporary, ponds (Jensen et al. 2008). Eggs are attached to submerged objects or pond bottoms.

Drying of breeding pond may result in total reproductive failure in some years (Semlitsch 1983). May incur heavy egg predation by eastern newt in some areas. See Worthylake and Hovingh (1989) for information on recurrent mass mortality associated with bacterial infection in mountains of Utah; it was suggested that nitrogen augmentation due in part to sheep grazing may be involved.

In New York, frequent predation occurred in small mammal runways, probably by short-tailed shrews (Madison and Farrand 1998).

In general, breeding occurs in spring in the north and at high elevations, in winter in the southern U.S., in late winter/spring and/or summer in the Southwest, and in late winter-early spring in the mid-Atlantic states. Typically the female oviposits within two days after picking up a spermatophore. Individual female deposit up to 1,000 eggs. Eggs hatch in about 2-5 weeks, depending on the temperature. Larvae metamorphose in their first or second summer, or they may not metamorphose at all (become sexually mature as gilled larvae). Reproductive success may be highly dependent on seasonal patterns of rainfall and temperature (Mitchell 1991). In South Carolina, reproductive success varied greatly in different years; little or no recruitment occurred during drought periods (Pechmann et al. 1991). Breeding aggregations may include a few or up to several hundred adults.