1
1
1
1
Female European frogs will play dead to avoid mating if several males climb on their backs at the same time during breeding season.
Researchers have found that female frogs have developed a number of strategies to avoid mating, including rolling around, grunting and even playing dead. They published their findings on October 11 in the journal Royal Society Open Science. European Frog (Rana temporaria) are notorious for breeding explosively, often gathering dozens of them to mate in ponds. Male frogs often outnumber females, meaning six or more may be competing to climb onto a female’s back at a time. In some cases, females can be killed inside these mating spheres, according to Carolin Dittrich, a researcher at the Natural History Museum in Berlin.
However, Female frogs have evolved several techniques to avoid mating. “Rather than being passive and helpless, we found that female frogs can use three key strategies to avoid males they do not want to mate with, either because they are not ready or do not want to mate,” Dittrich said.
Researchers collected male and female European frogs from a pond during mating season and placed them in water-filled tanks, each containing two females and one male. They then filmed the frogs for several hours. Of the 54 female frogs that were approached by a male, 83% responded by rolling onto their backs. This kept the male underwater and forced him to release the female to avoid drowning.
The female frog plays dead.
The team also found that 48 percent of the female frogs that had been mounted by a male emitted high-pitched growls and squeaks. The growls mimicked the calls that male frogs make to ward off other males. But Dittrich and his colleagues were unclear about what the higher-frequency squeaks meant. They also observed a third of the female frogs lying motionless with their limbs spread out for about two minutes after being grabbed by a male. They speculate that the female frogs were playing dead, although they couldn’t prove that this was conscious behavior. It could also be automatic response to pressure
Young and small females were most likely to use all three strategies to repel males, while older and larger individuals were less likely to play dead. As a result, young females were better at escaping approaching males. It is possible that younger females, having had fewer mating seasons, were more stressed by approaching males and reacted more strongly.
Although experiments may differ from real-life situations, similar tactics are widely documented in nature. The tactic of feigning death to avoid unwanted males occurs in many other animals, including dragonflies, spiders, and Spanish ribbed newts (Pleurodeles waltl). Understanding such behavior could aid future conservation efforts.
According to VnExpress