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Predator and Prey: The plight of the salamander




A few years back, I had the pleasure of attending the annual meeting of the Oregon Chapter of The Wildlife Society. Among the papers presented was one titled "The Effects of Stream Crossing Culverts on the Movements of Coastal Giant Salamander (Dicamptodon tenebrosus)."

Essentially, the researchers were interested in the role of culverts in the distribution and genetics of the Coastal Giant Salamanders living in the Coast Range. The results indicate that culvert design will greatly influence the genetic diversity, safety and distribution of salamanders. This, in turn, has led to the redesign of forest road culverts by U.S. Forest Service (USFS), Bureau of Land Management (BLM) and Oregon Department of Transportation (ODOT) engineers to ensure the welfare of the salamanders.

Never underestimate the political power of the lowly salamander...

Pretty neat work, and very helpful to the well-being of amphibians in general, which are facing serious problems from climate change (which, in spite of all the political balderdash, is for real) excessive radiation, loss of habitat, and predation from non-native fish. (That last one is also a real threat to a lot more than salamanders...)

We have only one species of native salamander roaming around Central Oregon that we have to worry about, the long-toed salamander, Ambystoma macrodactylum krausei. In addition, however, we do have rough-skinned newts, a close relative of salamanders that can be found in most of the high-country lakes. But salamanders and newts are like apples and oranges: they're both amphibians, but that's about all they have in common. For example, the venom under a newt's skin can knock you dead. As far as I know, salamanders do not possess that ability. (The scientific name, Ambystoma, by the way, has its roots in a Greek myth about an animal or being that was supposed to be able to live in fire.)

Long-toed salamanders are particularly vulnerable to predation by fish that have been introduced to portions of the Cascades in Washington and Oregon. When salamanders enter the water to breed, non-native fish gobble them up. If they are successful at laying eggs, then the larvae are eaten. Those that do make it to adulthood spend most of the time underground, roaming through abandoned ground squirrel tunnels, gobbling up occasional beetles, worms and anything smaller than themselves.

Long-toed salamanders can move about in very cold weather at night. Being out in broad daylight is very dangerous for salamanders, therefore, most are nocturnal - you never know who or what is going to eat you. In this part of the country, even summer nights can be very cold, especially after a thunderstorm leaves the ground covered with a thick carpet of hail and ice.

Right about now, female long-toed salamanders (that have already done the mating thing privately under a soggy log) are out looking for a pond to lay eggs, no matter how cold. I know of spring-fed ponds in the Sisters area that are ice-covered into April, but salamanders manage to find a thawed spot that will allow them to enter the frigid waters and lay their eggs anyway.

Salamanders begin their lives as predators, and spend their adult life in the same role. As larva, they resemble tadpoles, and are sometimes known as axoltls (ox-OH-lotals). In this stage, they don't have lungs, but breathe with external gills. Large salamanders such as the tiger and Pacific giant sometimes never metamorphose into adults, but remain in the axoltl stage, even breeding in this stage.

The largest salamander in the world is the tiger salamander, ambystioma tigrinum. There are several species of this beautiful amphibian that range all the way from northern Florida into the Midwest and beyond into most of the Southwest, as well as parts of Montana, Idaho, eastern Washington and Canada. For some unknown reason they are rare in Oregon.

On one hand, these colossal salamanders make an excellent meal for snakes, turtles, herons and fish, while on the other, the salamanders snack on insects, earthworms, small mice and even other amphibians. Unfortunately, fisher folk in many places prefer to use tiger salamander axoltls for bait, which may eventually result in only one species of tiger salamander.

With the increased use of forest roads by a variety of motor vehicles amphibians will continue to be in jeopardy. Adult western toads have a difficult time getting across paved roads in places like Black Butte Ranch and Sunriver, especially after a warm shower in spring and summer. Wet nights are ideal for amphibians to wander around and expand their range. It would be very helpful if motorists were more conscious of the animals that share the roadway and do all they can to not run them over, and if fishery biologists and sport fisherman would think twice before planting fish in what were once fishless lakes.

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