Spotted Salamander
Ambystoma maculatum
Summary: Limited to the more heavily forested parts of the region. Still relatively common in northern LaPorte County and at a few Cook and Will County localities. Lake County Illinois populations have declined or disappeared.
Description: A robust, medium to large salamander, 4.5 to 9.5 inches (11-24 cm) total length. Black, dark gray, or brown-black above with paired rows of yellow spots on the dorsolateral surface. Occasionally the front-most spots on the head and neck may be orange. The underside is medium gray. The spotted salamander can be confused only with the tiger salamander, which also has yellow spots. The spotted salamander has yellow spots only on the upper surfaces, and never on the lower sides.
Distribution and Status: Spotted salamanders occur at scattered locations in more heavily forested parts of the Chicago region. There are records from parts of Cook, Lake, DuPage, and Will Counties in Illinois, and from Porter and LaPorte Counties in Indiana. Spotted salamanders are common at only a few of the Illinois localities, and only a very few specimens have been reported from Lake County since 1987. They are more widespread and abundant in the more heavily wooded eastern part of the region. In the late fall of 1999, juveniles were easily found around wetlands in northern LaPorte County.
Habitat: Spotted salamanders are associated with closed canopy mesic forests. In Indiana, the largest numbers are found in mature beech-maple forest. Illinois sites are generally mesic oak woodland, sometimes with inclusions of northern flatwoods. In a diverse oak woodland in southwest Cook County, spotted salamander numbers dropped by half the year after a tornado opened a large gap in the tree canopy (Mierzwa, 1998).
Petranka (1998) reports that in other parts of the range adult spotted salamanders are common in floodplain forests. However, I have so far not found the species in that habitat type in the Chicago region.
Breeding occurs in vernal ponds, marshes, and swamps within, or at least mostly surrounded by woodland. Only wetlands which on average hold water into early to mid July are suitable.
Phenology: First emergence may occur as early as the first week of March or as late as early April, depending on weather. Spotted salamanders require slightly warmer temperatures than blue-spotted salamanders, wood frogs, or chorus frogs, and they usually appear a few days to a week later than those species. Peckham and Dineen (1954) observed large movements in Indiana at 5.5 to 11.0 degrees C. High humidity is essential, with most movement at night and during or imediately after rainfall. Spotted salamanders tend to return to the same ponds via the same route year after year (Phillips and Sexton, 1989; Shoop, 1965). Animals moved 130 to 500 meters away were able to locate their home ponds within as little as 11 days (Shoop, 1968).
The courtship of spotted salamanders was described by Arnold (1976). The distinctive large, rounded and firm egg masses may be found in ponds during early April, attached to submerged branches. Eggs hatch in a few weeks. In 1999 larvae left Will County ponds from June 29 through the end of July.
Adults spend most of their lives underground and they are usually difficult to find on the surface even in the breeding season, except where populations are large.
Literature Cited
Arnold, S. J. 1976. Sexual behavior, sexual interference, and sexual defence in the salamanders Ambystoma maculatum, Ambystoma tigrinum, and Plethodon jordani. Zeitschrift fur Tierpsychologie 42:247-300.
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.
Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press. xvi + 587p.
Phillips, C. A., and O. W. Sexton. 1989. Orientation and sexual differences during breeding migrations of the spotted salamander, Ambystoma maculatum. Copeia 1989:17-22.
Shoop, C. R. 1965. Orientation of Ambystoma maculatum: movements to and from breeding pools. Science 149:558-559.
Shoop, C. R. 1968. Migratory orientation of Ambystoma maculatum: movements near breeding pools and displacements of migrating individuals. Biological Bulletin 135:230-238.
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| Updated: October 9, 2007
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