Berlin: A new study has found that frogs appear to feign death as a drastic action to avoid unwanted male attention.
According to the findings, female European common frogs do not simply put up with the male scramble for mates—a situation in which several males can end up clinging to a female.
“It was previously thought that females were unable to choose or defend themselves against this male coercion,” Dr. Carolin Dittrich, the first author of the study from the Natural History Museum of Berli, said. “Females in these dense breeding aggregations are not passive, as previously thought,” the researcher noted.
In the study published in the journal Royal Society Open Science, Dr. Dittrich and her co-author, Dr. Mark-Oliver Rödel, reported how they placed each male frog in a box with two females: one large and one small. The mating behaviour was then recorded on video.
The results, obtained from 54 females who experienced the clutches of a male, revealed that 83 percent of females gripped by a male tried rotating their body. Release calls such as grunts and squeaks were emitted by 48 percent of clasped females, all of whom also rotated their bodies.
Tonic immobility, stiffening with arms and legs outstretched in a pose reminiscent of playing dead, occurred in 33 percent of all females clasped by a male. Researchers further noted that smaller females more frequently employed all three tactics together than larger ones.
“I found a book written in 1758 by Mr. Rösel von Rosenhoff describing this behaviour, which was never mentioned again,” Dr. Dittrich remarked. The research team observed that tonic immobility could be a stress response. The team found this was more common in smaller and therefore younger females, which could be a result of greater stress arising with less experience of reproduction.
According to the analysis, the three tactics allowed at least some females to evade the clutches of the males. “Displaying mate avoidance behaviour resulted in the escape of 25 females,” the study added.
However, the researchers acknowledge the behaviours may have other purposes, suggesting that while female rotations may help them dislodge a male, it could be a way to test the male’s strength and endurance.
“In the real world, we often observe the formation of mating balls, but also that females can more easily dive away because there is more structure and places to hide,” Mr. Dittrich shared, adding that even though the tactics identified could be successful in nature, the degree of possibility is not yet clear.
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