This is the most widespread salamander in the Chicago region, with numerous records available for most counties. It is especially common in former savanna regions, although it is often overlooked because of secretive habits and a limited period of surface activity.
Description: The largest Chicago region terrestrial salamander, usually 6.0 to 9.5 inches (15-21 cm) but occasionally up to 12 inches (30.5 cm) total length. Black or dark gray above with small irregular yellow spots or blotches scattered over the sides and upper surfaces. The underside is gray. The adult tiger salamander can be confused only with the spotted salamander, which has more regular yellow spots in distinct rows. The tiger salamander has yellow spots randomly arranged, and concentrated most heavily on the lower sides.
As with other Ambystoma, juvenile tiger salamanders just emerged from the ponds are olive green. Over a few days to a few weeks, the ground color darkens, and then small yellow flecks begin to become noticeable on the lower sides. At this stage tiger salamanders can be identified by size alone; at five to six inches, metamorphs are more than double the length of other local Ambystoma of similar age.
Distribution and Status: Tiger salamanders are common and widespread through most of the Chicago region. West of the Fox River, and in more open areas elsewhere, they are usually the only salamander present. Tiger salamanders occur in every county in the region. They are absent from some of the more extensive mesic forests, but are typically found in more open situations nearby.
Habitat: Optimal tiger salamander habitat consists of open savanna and woodland, or clusters of savanna groves in a prairie matrix, interspersed with semi-permanent wetlands. Although tiger salamanders may persist in once open oak groves now overgrown from fire suppression, they are usually uncommon in such situations. Where open-grown trees, dense herbaceous cover, and long-lasting wetlands occur the species can be abundant. In McHenry County, tiger salamanders responded well to concurrent savanna, grassland, and wetland restoration (Mierzwa, 1998).
Breeding occurs in marshes and ponds which on average hold water into at least mid-July.
Phenology: Tiger salamanders emerge in early spring, usually before the end of March. Although they require slightly warmer air and soil temperatures than some other early spring amphibians, in open habitat a succession of sunny days can thaw the ground and allow movement while nearby forested sites are still covered in snow.
In Indiana, adults remain at the ponds from 10 to 29 days, with females departing more rapidly than males (Peckham and Dineen, 1954). Breeding occurs in the ponds, with the loose egg masses attached to sticks and branches. Eggs hatch in 19 to 31 days (Sever and Dineen, 1978). Just over half an inch long at hatching, the larvae grow rapidly and they are soon among the top water column predators. They may begin to leave the ponds by mid-July, but in more permanent water will sometimes remain in larval form well into August. In optimal habitat, mass migrations away from ponds can occur during late summer rains. In McHenry County in 1993, I captured over 1000 juveniles leaving a savanna pond over a span of a few weeks. The same year, county staff reported moving up to 200 salamanders from nearby roads in a single evening.
Adults are secretive and not often encountered on the surface. They disperse up to several hundred meters from the pond. Although tiger salamanders can dig in loose soil, they usually occupy burrows created by small mammals or crayfish. Nocturnal flashlight surveys sometimes reveal tiger salamanders sitting in wait inside burrow mouths, ready to seize any unwary prey.
Mierzwa, K. S. 1998. Status of northeastern Illinois amphibians. Pp. 115-124 in: M. J. Lannoo (ed.), Status and Conservation of Midwestern Amphibians. Univ. of Iowa Press. xviii + 507p.
Peckham, R. S., and C. F. Dineen. 1954. Spring migrations of salamanders. Proceedings of the Indiana Academy of Science 64:278-280.
Sever, D. M., and C. F. Dineen. 1978. Reproductive ecology of the tiger salamander in northern Inndiana. Proceedings of the Indiana Academy of Science 87:189-203.