Amphibians
Streamside Salamander
Ambystoma barbouri · also called streamside salamanders
Almost every mole salamander breeds in a still, fishless pond. The streamside salamander does not, laying its eggs instead in flowing woodland streams, gluing each one individually to the underside of a submerged rock where a typical soft egg mass would simply be swept away.
Overview
The streamside salamander, Ambystoma barbouri, lives in deciduous forest with clean, flowing streams across parts of the central United States. Adults hunt small invertebrates in leaf litter and soil, spending most of the year underground except during a brief breeding migration to streams.
Built for a current
Eggs attached to submerged rocks and larvae that hatch already relatively well developed both reflect adaptations to breeding in moving water rather than the still ponds most of its mole salamander relatives use. It closely resembles, and can hybridise with, the related small-mouthed salamander where ranges overlap.
Status
Least Concern overall but decreasing locally, since its tie to clean, flowing streams makes it sensitive to pollution, sedimentation, and the loss of streamside forest cover.
Streamside Salamander: common questions
Why is it unusual for a mole salamander to breed in a stream?
Most species in the genus Ambystoma, the mole salamanders, are strongly associated with breeding in still, typically fishless ponds and temporary pools, since flowing water can sweep away a typical soft egg mass and expose larvae to different challenges such as stronger currents and, potentially, fish predators. The streamside salamander's shift to breeding in flowing streams instead represents a distinctive departure from this usual pattern within its genus, requiring specific adaptations to its egg-laying behaviour and larval development to succeed in this different environment.
How do streamside salamander eggs survive being laid in moving water?
Rather than laying eggs in a larger, more exposed mass the way many pond-breeding relatives do, female streamside salamanders attach their eggs individually or in small clusters directly to the underside of submerged rocks within the stream, anchoring them securely against the current in a way that a looser, floating egg mass could not withstand in flowing water.
Can streamside salamanders and small-mouthed salamanders interbreed?
Yes, in areas where their ranges and habitat preferences overlap, streamside salamanders and the closely related, very similar-looking small-mouthed salamander can hybridise, occasionally complicating efforts to identify individuals with certainty based on appearance alone, since the two species are quite closely related and share considerable physical similarity to begin with.
What is the biggest threat to streamside salamander populations?
Because the species depends specifically on clean, flowing woodland streams for successful breeding, pollution, sedimentation from nearby land erosion, and the loss of forested cover along stream corridors are considered the most significant threats, since any of these can degrade the specific stream conditions the species needs for egg attachment and healthy larval development, even if the broader surrounding forest habitat used by adults remains largely intact.