A Female Salamander Giving It to Her Mate

Dec. 15, 2003 — Unfaithful male salamanders returning home might find their female partners waiting with rolling pins, new research reveals.

In a study slated for publication in the journal Animal Behavior, behavioral ecologist Ethan Prosen of the University of Louisiana in Lafayette shows that red-backed female salamanders (Plethodon cinereus) sexually intimidate their Casanova partners by punishing them with bites and aggressive postures.

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"We do not know of any other animals where the females use this coercion and the males also use coercion," Prosen told Animal Planet News.

It known that male salamanders, eager to monopolize paternity, get violent toward female partners that have visited other males. But so far no scientist had predicted that females would likewise get aggressive.

In the autumn courtship season (mid-October) and near the end of the spring courtship season (mid-April), Prosen collected from the wild several established pairs of salamanders — those sharing the shelter of one rock — as well as single males and females.

In the laboratory, he placed the amphibians in different containers. By letting each male spend five days alone or with another female, he forced the male salamanders to be polygynous or monogamous.

In the autumn courtship experiment, paired females were far more hostile toward partners that had been with other females.

"They increased the amount of time spent threatening the fickle males, spending more time in a posture known as ATR (All-Trunk-Raised), in which they lift their entire length off the ground in the effort to look bigger. In some instances the females escalated to biting the males," Prosen said.

During the spring courtship experiment, however, the females did not punish the unfaithful partners. Prosen believes the change in their behavior reflected a different priority, as they were preoccupied with locating suitable nesting sites.

Since the male salamanders do not directly contribute to care for the offspring, it isn't clear why the females want them to be monogamous.

According to Prosen, they may help to drive others off their territory. This additional defense might ease the burden on females or even indirectly help protect from other salamanders that would cannibalize the eggs or newly hatched young.

"This is an interesting and important study. It tests an explicit theory of mating systems, and like a number of other studies, suggests that the social architecture of some salamander populations can be complex," ecologist John Maerz of Cornell University in Ithaca, New York, told Animal Planet News.

However, since this is the first study to demonstrate female retaliatory behaviors, it will need to be repeated to validate the findings," he said.