Identification

These are relatively large and stocky gray, brown, or black salamanders. Adult Streamside Salamanders can grow to 5-7 in (120-180 mm) in total length. Adult coloration is gray to dark brown with lighter gray lichenate mottling on the sides. Both this species and the Small-Mouthed Salamander have a relatively small head and blunt snout. The two are very morphologically similar, but they can usually be distinguished by geographic range and breeding habitat. Streamside Salamanders attach large clumps of eggs to the underside of submerged rocks and occasionally logs and clumps of leaf litter. This is a distinguishing feature of this species and separates it from all of the other species in its genus, most of which lay their eggs in clumps attached to aquatic vegetation. Despite being a stream-breeding species, Streamside Salamander have larvae more typical of pond-dwelling salamanders--a vestige of their evolutionary history. Small larvae are dark with 3-6 dorsal blotches that fade with age. In general, larval Streamside Salamanders are similar in appearance to larval Small-Mouthed Salamanders (Ambystoma texanum), but tend to be darker and larger at any stage of development.

Small-Mouthed Salamanders are physically indistinguishable from this species, with the exception of some minor differences in tooth and bone structure that are not easily observed in the field. The most easily observed between the two species is in in their breeding behavior. Small-Mouthed Salamanders prefer ephemeral pools and ponds and lay eggs in smaller clumps attached to vegetation, but Streamside Salamanders breed primarily in streams and smear large numbers of eggs on the underside of submerged rocks and logs. The only region in which the two species could potentially be sympatric (i.e., occurring side by side) is in southeastern Indiana. Flat, seasonally wet uplands and floodplains are the most likely types of habitats in which the species would co-occur, possibly using similar breeding habitat (ditches and sloughs). Jefferson's Salamanders (Ambystoma jeffersonianum) co-occur with this species throughout its range and are similar in appearance, but Jefferson's Salamanders tend to have more blue/gray speckling as opposed to the lichenate coloration that is typical in Streamside Salamanders. Jefferson's Salamanders also are generally more slender with elongated snouts.

Ecology and Conservation

This species is typically found in hilly, wooded uplands dissected by deep ravines and rocky ephemeral creeks. They also occur in seasonally wet, upland flatwoods near the edge of their range in the state. There, they breed in sluggish gravel-bottomed creeks and ditches. Streams where breeding occurs are usually shallow and often ephemeral with many large flat rocks and a limestone bottom. They will also utilize sluggish creeks and roadside ditches. Though Streamside Salamanders utilize streams with fish, they preferentially deposit eggs in pools where fish are absent or scarce. Outside of the breeding season, adults aestivate in neighboring uplands and are rarely encountered. Larval Streamside Salamanders feed on small aquatic invertebrates while adults feed on a variety of terrestrial invertebrates. Adults may also feed occasionally on aquatic invertebrates.

Streamside Salamanders breed in the winter, and they can be found under rocks along streams as early as November. The breeding season is prolonged and females may deposit eggs anytime from January to March. The females attach their eggs to the underside of submerged rocks. Adults and occasional juveniles can be found in the vicinity of the streams throughout spring, and larvae are prevalent in streams during late April and May. Most salamanders will metamorphose in June, and it is not uncommon to find juveniles under rocks along drying streams at this time. Outside of the breeding season, Streamside Salamanders are fossorial and largely inactive on the surface.

Despite their restricted range in the state, Streamside Salamanders are abundant in many of southeastern Indiana's streams and will breed at disturbed and extensively altered sites. Streamside Salamanders are considered a species of special concern in Indiana due to their restricted range. Their status according to the IUCN Red List is “Near Threatened”, and some populations are believed to be declining.

Distribution

Streamside Salamanders are endemic to a small region including southwestern Ohio, southeastern Indiana, and northern Kentucky. Isolated populations have also been found in Tennessee. Streamside Salamanders are restricted to the southeastern part of the state and some of the south-central counties bordering the Ohio River. There may be some range overlap with Small-Mouthed Salamanders in areas southwest of Jefferson County.

Taxonomy

There are no recognized subspecies of the Streamside Salamander (Ambystoma barbouri). It belongs to the family Ambystomatidae, which is represented in Indiana by eight species (plus the unisexual Ambystoma)--the most of any state!

Literature Cited

Bogart, J. P., K. Bi, J. Fu, D. WA Noble, and J. Niedzwiecki. 2007. Unisexual Salamanders (Genus Ambystoma) Present a New Reproductive Mode for Eukaryotes. Genome 50:119-136.

Conant, R. and J. T . Collins. 1998. Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin, New York, NY.

Garcia, T. S. and A. Sih. 2003. Color Change and Color-dependent Behavior in Response to Predation Risk in the Salamander Sister Species Ambystoma barbouri and Ambystoma texanum. Oecologia 137:131-139.

Kats, L. B. and A. Sih. 1992. Oviposition Site Selection and Avoidance of Fish by Streamside Salamanders (Ambystoma barbouri). Copeia 1992:468-473.

Minton, S. A. Jr. 2001. Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN.

Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institute Press, Washington D.C.

Robertson, A. V., C. Ramsden, J. Niedzwiecki, J. Fu, and J. P. Bogart. 2006. An Unexpected Recent Ancestor of Unisexual Ambystoma. Molecular Ecology 15:3339-3351.