Fascinating Survival Strategy: Female Frogs Mimic Death to Avoid Unwanted Mating

European common frogs have a unique mating behavior known as a “mating ball.” In their quest to reproduce, males actively seek out and cling to outnumbered females, even if they are already targeted by other males. This struggle for dominance can often result in potential harm or drowning for the females involved, as per a report by Science. However, recent research conducted by Carolin Dittrich, an evolutionary and behavioral biologist at Berlin’s Natural History Museum, reveals that females are not helpless victims in this scenario. They have developed strategies such as body movements, vocalizations, and even playing dead to escape from male coercion.

In laboratory experiments, researchers observed male frogs clinging to 54 different females. Out of these females, 83% rotated their bodies, 48% emitted calls mimicking male “release calls” that confuse the males, and 33% displayed “tonic immobility” – a state where their limbs stiffen and they appear motionless, as if playing dead. Tonic immobility is typically used as a defense mechanism against predators, so its presence during mating was unexpected, according to Dittrich as reported by Science. However, she notes that some male frogs lost interest and swam away when faced with these behaviors. Interestingly, tonic immobility during frog mating was described in a book dating back to 1758 but has since been overlooked.

Although the study involved groups with one male and two female frogs, there was no actual “mating ball” formation. Nevertheless, the females’ display of mate avoidance behaviors resulted in the escape of 25 females, as indicated in a study published in Royal Society Open Science. The rotation of the body helps females break free from a male’s cling, but researchers suggest it might also serve as a way to assess the strength and endurance of potential mates. Additionally, tonic immobility could be a stress response exhibited by inexperienced frogs during reproductive encounters. Younger and smaller female frogs tended to play dead, rotate their bodies, and mimic male release calls, the study found. (Read more frog-related stories.)