She salamanders punish fickle mates.

Coming home after a few days with another female doesn't turn out well for male red-backed salamanders.

In the animal soap opera more commonly recorded in scientific literature, a male gets violent if a female visits other males, observes Ethan Prosen of the University of Louisiana-Lafayette. The male's drive to monopolize paternity explains that story. Prosen hadn't predicted that females would likewise get nasty.

A male and female often share the shelter of one rock. Prosen and his Louisiana colleague Robert G. Jaeger collected 40 such pairs as well as 170 singletons. In the laboratory, the scientists presented female salamanders with four situations: the return of the original male or of an unfamiliar fellow after the males spent 5 days with another female or 5 days alone.

Strange males didn't draw much aggression regardless of social history. However, familiar males received threefold as much threat posturing from their rockmate if they had spent time with another female than if they returned from a solitary spell. Also, the fickle males were the only ones that the females bit.