salamander stories

April 26, 2005

in Natural history

It’s been a few years since I’ve walked down near the floodplain in early spring and Sala_thturned over logs to look for Red-backed Salamanders (Plethodon cinereus). The other day I did just that, and was pleased to find one of these petite amphibians under nearly every log. Most were like this one on the right that I photographed – it’s easy to see how they got their name. But some were all gray, or “lead-backed.” Generally, the lead-backed forms are more common in lower elevations.  In the Midwest, lead-backs more common further south, being uncommon in Wisconsin and Minnesota.

Where they are found in the eastern U.S., red-backs are usually the most common salamander, and although extremely inconspicuous, their biomass may outstrip that of all the breeding birds and small mammals combined in a given forest. They belong to the family Plethodontidae, the lungless salamanders, which breathe through their skin. This intimate interface with the world around them makes them sensitive to environmental conditions. Plenthodontids make good indicators of woodland health.

Red-backed Salamanders are completely terrestrial, defending a small territory where they live under rocks or logs on the forest floor. Slowly prying up rotting limbs from the leaf litter, I uncovered earthworms and isopods, ants and beetles, and once a fortunately dull and sleepy hornet. Often I’d encounter one of those large, orange centipedes, but never under the same shelter as a Red-backed Salamander. Both of these organisms occupy a very similar niche, and salamanders respond aggressively towards centipedes. Since the centipedes are blind and don’t react to the visual threats presented by the amphibians, the salamanders bite them to drive them away.

Red-backed Salamanders must live in moist habitats, but will suffocate in water, which they do not require to reproduce – the larval stage is completed entirely in the egg. Tiny, fully formed salamanders emerge from the eggs, laid in clutches of fewer than 20, which are brooded by the females for six to nine weeks beginning in June. Hatchlings remain with the female for up to another two weeks. During this entire maternal period, females rarely eat, relying on their fat reserves until the hatchlings absorb their yolk sacs and begin to forage on their own. The hungry females can then spend the rest of summer building up their fat stores once more, this time to prepare for winter.

It is probably this requirement – the need to put on fat – that led female Red-backed Salamanders to develop a curious habit. They rip apart and inspect the feces of other salamanders. They don’t consume the excreta, just disassemble and examine it; researchers refer to it as “fecal squashing.” Because only females engage in fecal squashing, and since the turds contain chemicals that identify the gender and even the individual that produced them, it was assumed that this behavior somehow helped females assess the diet, and therefore the quality of the territory, of potential mates. It has come to pass (okay, I couldn’t resist) that the females do use stool squashing to evaluate prey availability in a territory, apparently in order to meet their own higher energy demands; experimental females fed low quality diets did more fecal squashing than their well-fed sisters. Males don’t let this tendency go to waste (sorry), they produce more poop when they sense females nearby, so as to increase the chance of encountering more females in their territories.

Carefully, I replaced the refugia I had disturbed, stood back, and looked out over the quiet forest. Tall trees, no understory, thick layer of fallen brown leaves interrupted by decaying limbs and branches. No sign of the small dramas and full lives taking place just above the soil.


GrrlScientist April 26, 2005 at 7:56 pm

Males produce more poops when females are nearby? Is that more (smaller) poops or do they eat lots more so they poop more (big) turds?

While I am wondering today, I also wonder why poop, as a topic, is so fascinating?


Nuthatch April 27, 2005 at 8:55 am

The study I read (Animal Behaviour 68:489-494) indicated only that "males will accelerate pellet production when exposed to female odours." Poop — universal, fundamental, and sometimes still surprising!

jvl April 27, 2005 at 1:38 pm

nice piece, you should consider trying to sell it…

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Robin Datta May 14, 2005 at 8:45 am

Thanks for the salamander stories. I got here from the Panda's Thumb RSS feed via Tangled Bank.It finally anwsered a question that had been lingering in my mind since 1991: what were the creatures that I found under some concrete downspout rain gutter channels that I was moving to trim adjacent grass before I left my home in Hopkinsville KY, where I had lived for 7 years (less 6 months in BushDaddy's war). I know now that they were lead-backed salamanders! They had a claim to the territory long before any humans, and I am glad that I left them in peace. Thank you for the information!

Nuthatch May 15, 2005 at 4:05 pm

Glad to enlighten!

Dick Stevens September 26, 2008 at 4:40 am

Is excreta a dark substance with a white tip? I find many of these animals in my garage on the floor. When dry, they are difficult to sweep. I've seen them scoot across the floor in the garage. They do not harm anything and are interesting to watch. They seem to have very good eyesight. When they see movement, they "scoot" rapidly.
Even though green, there's a bubble under their mouth which is red most of the time when inflated.

Nuthatch September 26, 2008 at 5:43 am

Dick, the creatures you describe in your garage are not salamanders, but anoles, which are small lizards. I'm not familiar with their poop, but dark with a white tip (which would be the equivalent of their urine) sounds plausible, since that's what much bird poop looks like.

John Evans August 23, 2009 at 10:17 am

I have these salamander type creatures that
come onto my outdoor breezeway that leave behind a their poop which is also brown with a white tip.However they are not anoles.They are brown with a red head that fades into the brown acreoss their back.Is the pop something I should worry about(Bacteria wise) or are they harmless.How do you keep them away?

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