Female frogs fake their death to avoid mating with males, study finds

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Female European common frogs frequently feign death to avoid unwanted male attention, scientists researching aggressive mating habits found.

The findings disprove the commonly held notion that females passively submit to the desires of male frogs scrambling for mates, the authors of the study said.

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“It was previously thought that females were unable to choose or defend themselves against this male coercion,” said Dr. Carolin Dittrich, co-author of the study published in Royal Society Open Science.

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“Females in these dense breeding aggregations are not passive as previously thought,” she said.

Dittrich and her co-author, Dr. Mark-Oliver Rödel, placed each male frog with two females, one large and one small, in a box for an hour.

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The results showed that from the 54 females who experienced the clutch of a male, 83 per cent rotated their bodies, appearing dead, and 48 per cent released grunts and squeals to fend off the male aggressor.

Scientists coined the term “tonic immobility”, a strategy used by females where they rotate their bodies with stiff arms and legs outstretched to avoid mating with males.

The tactics used by female frogs allowed 25 of them to escape the clutches of the males, the researchers observed.

Female frogs will oftentimes find themselves in a situation where several of their male counterparts will cling to them, ending in a fatal fate. According to Science Alert, it’s not uncommon for six males to surround and cling to a single female.

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That’s due to the brutal mating habits of this particular species, the European common frog.

These frogs have a very short mating season resulting in aggressive male behaviour.

“Usually, there are more males than females in the breeding aggregation,” Dittrich told NPR.

“That means that males are fighting to get access to the females. And sometimes, a lot of males can cling to one female, which leads to the drowning of the female.”

Dittrich notes that this behaviour exhibited by female frogs is not a conscious decision, but rather a survival strategy.

Despite the findings of the study, researchers acknowledge the behaviour may have other purposes. When the female rotates her body to dislodge her male counterpart, it may indicate her testing his strength and endurance that could help fend off rivals.

“I think even if we call this species a common frog and think we know it well, there are still aspects we don’t know and perhaps haven’t thought about,” Dittrich said.

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