The Carlisle Mosquito Online

Friday, April 8, 2005

Features


Redback Salamander

(Photo by Kay Fairweather)

It is the time of year when mole salamanders (i.e. the yellow spotted, the blue spotted and the Jefferson) migrate to vernal ponds to breed. I had hoped to see some last Saturday night when conditions seemed right for a mass migration, an aquatic orgy — it was the first night of the spring with a temperature of around 40 degrees F. and raining. I saw a few frogs but no salamanders. It may have been too cold and I will go looking again on the next rainy night. Meantime, I'd like to say a few words on behalf of one of the terrestrial salamanders.

Name: The redback salamander is Plethodon cinereus. Along with the four-toed salamander, it is a member of the plethodontidae, the lungless salamanders. Plethodon means many teeth and refers to the long row of teeth found in members of this genus. Cinereus means ash-colored and is used in the scientific name of many plants and animals. For example, the koala is Phascolarctos cinereus; the masked shrew is Sorex cinereus; the hoary bat is Lasiuris cinereus.

When and where found: The redback is a common salamander and can be found in moist lowland deciduous forests across a wide range of eastern North America. I found the one in the photograph under a small piece of fallen bark in my back yard on April 3. If you are burning the wood and bark that fell in the winter, check the damp underside before you toss it on the fire. You might save one of these critters. It is only a myth that salamanders are not harmed by fire.

Distinguishing characteristics: The redback salamander has a slender blue-black body and some have the obvious red stripe down the back; others don't. These other ones are called the "lead phase" form or leadbacks. This means you can have a leadbacked redback but you can't have a redbacked leadback. Whether red or lead on the back, the lower sides of the body are speckled blue. There is also a rare form which is entirely red. The redback can reach four to five inches in length. The leadback form can be distinguished from the four-toed salamander by its larger size, no constriction at the base of the tail, and by the five toes on the hind legs. It can be distinguished from the Jefferson and blue-spotted salamanders by its narrow head and body. I don't think you will notice the "many teeth" that the genus is named for. I didn't notice any teeth at all. I will look more closely the next time I find one.

Behavior: Redbacks are entirely terrestrial although they may wander into damp vernal pool areas as they are drying up. They require a moist skin at all times for respiration so they can forage further afield during and shortly after rain. They feed on a large variety of invertebrates mainly foraging at night. Their foraging territory can become seriously restricted during dry periods so they are "pulse feeders" eating large amounts when they can and living off body fat when conditions are poor. Mating occurs in the fall. In the following spring the female lays up to 14 eggs in a clump in a damp protected place and stays with her eggs until they hatch.

Predators: Redback salamanders are preyed on by snakes, robins, jays, skunks, raccoons, and large frogs. Like the four-toed salamander, the redback is able to shed its tail if needed to escape predators. It can grow a new tail which is often a paler color than the original.

References: Leo P. Kenney, Matthew R. Burne, A Field Guide to the Animals of Vernal Pools; University of Michigan Museum of Zoology at http://animaldiversity.ummz.umich.edu (search on plethodon).


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