Houston ChandlerViews:
Spotted Salamander (Ambystoma maculatum) from the mountains of Virginia. – Houston Chandler
On cool rainy nights from late fall to early winter something incredible happens across much of the United States. Ambystomatid salamanders leave their subterranean refuges and migrate towards breeding wetlands, often in large numbers that can transform shallow wetlands into a frenzy of salamander activity. Many species in this group obtain impressive sizes and everyone should brave a rainy night at least once in their life to watch these incredible animals shuffle across the ground in search of ideal breeding habitat.
A Jefferson Salamander (A. jeffersonianum) making its way to a breeding pond in early March. – Houston Chandler
The family Ambystomatidae is composed of 32 species, all of which can be found in North America. The highest number of species occur in portions of the eastern U.S. and in several cases multiple species can be observed breeding in the same wetlands each year. Ambystomatid salamanders are commonly referred to as mole salamanders (not to be confused with the Mole Salamander [A. talpoideum]) because they spend a significant portion of their lives underground. In fact, many species can only be observed during breeding migrations or as larva in breeding wetlands. This makes many portions of their adult life difficult or even impossible to study, and we still know surprisingly little about the adult portion of the life cycle in most species.
Mole Salamander (A. talpoideum) from the Florida panhandle. – Houston Chandler
Most ambystomatids have a life cycle that consists of a terrestrial or aquatic egg and an aquatic larval phase that undergoes metamorphosis to reach a terrestrial adult phase. This is the classic amphibian life cycle that is necessitated in many cases by breeding in ephemeral water bodies that are destined to dry up at some point in the future. However, some species of ambystomatid salamanders are actually paedomorphic (having juvenile trails as adults). In these species, adult salamanders retain gills and live in permanent aquatic habitats. The Axolotl (A. mexicanum) is a well-known example of this life history strategy, but it also occurs in other species. This includes the Mole Salamander that can have both terrestrial and paedomorphic adults in the same population. One other deviation from the typical pond-breeding amphibian life cycle is laying eggs terrestrially that then hatch into larvae when they are inundated by rising water levels. Both Flatwoods Salamanders (A. bishopi and A. cingulatum) and Marbled Salamanders (A. opacum) use this strategy. In the eastern U.S., female Marbled Salamanders can often be found under logs with a clutch of eggs, waiting for the next rain event.
A group of Eastern Tiger Salamanders (A. tigrinum) captured in a borrow pit on the Orianne Indigo Snake Preserve.
Unfortunately, many ambystomatids have experienced population declines in recent years and several species are now critically endangered. The omnipresent threat of habitat loss and alteration is generally the main culprit, although a variety of other stressors can impact salamander populations. Climate change is likely to be a major challenge for the conservation of imperiled ambystomatids because most species rely on predictable climatic events. For example, Flatwoods Salamanders have already experienced reduced quality in breeding wetlands in recent years (Chandler et al. 2016). This trend will likely continue and may be exacerbated by severe storms impacting the few remaining populations (Walls et al. 2020). It will take a combined effort from many different conservation partners to insure that populations of ambystomatid salamanders remain on the landscape and remain common where they are currently common. These salamander serve important roles in both terrestrial and aquatic ecosystems, linking the two through a variety of nutrient and energy cycles.
Gravid female Reticulated Flatwoods Salamander (A. bishopi) making her way into a breeding wetland. – Houston Chandler
Although sometimes chilly and wet, I will always cherish the nights that I have spent watching these incredible salamanders go about their life. They piqued my interest in salamanders from a young age and contributed to my Master’s Degree and now to my PhD. Everyone should get to experience an Ambystoma Night at least once!
Literature Cited
Chandler, H. C., A. L. Rypel, Y. Jiao, C. A. Haas, and T. A. Gorman. 2016 Hindcasting historical breeding conditions for an endangered salamander in ephemeral wetlands of the southeastern USA: Implications of climate change. PLoS ONE 11:e0150169.
Walls, S. C., W. J. Barichivich, J. Chandler, A. M. Meade, M. Milinichik, K. M. O’Donnell, M. E. Owens, T. Peacock, J. Reinman, R. C. Watling, O. E. Wetsch. 2019. Seeking shelter from the storm: Conservation and management of imperiled species in a changing climate. Ecology and Evolution 9:7122–7133.
