The breeding season for female grass frogs brings many challenges: males strive to mate with as many females as possible, and sometimes females find themselves literally surrounded by numerous males. This is not as harmless as it may seem: a female can suffer serious injuries or even drown if she remains under the weight of males in the water for too long. Although frogs can absorb oxygen through their skin, they also have lungs, and they cannot do without breathing air, especially in conditions of low oxygen content in the water.
However, females use several tricks to get rid of overly persistent males. First, they mimic a special dissatisfied “quack” that males make when another male tries to mate with them. During the mating season, male grass frogs strive to mate with literally everything that moves, including toads and salamanders; not to mention males of their own species. If a male grass frog suspects that he has been mistaken for a female, he signals not to waste time on him – and this signal, as already mentioned, females are capable of mimicking.
Secondly, females can pretend to be dead by stretching out their front and back legs and freezing in a pose resembling rigor mortis. A male may try to court such a female for a while, but upon failing to grasp her, he quickly retreats.
Usually, the “play dead” tactic is used against predators; female grass frogs are perhaps the first known example of such a tactic being used to get rid of an unwanted suitor.
