first_imgToo many suitors and too little time may lead female túngara frogs to settle for second best when it comes to choosing a mate. Typically, males of the species (Engystomops pustulosus) employ two types of calls to entice a partner: a “whine” and a “chuck.” Some males only use whines, but others tack the lower pitched chucks to the end of a call (as in the above video), a combination that females find irresistible. As a result, biologists have reasoned that the tiny amphibians should behave “rationally,” consistently selecting the male with the most ear-catching call. Now, a new study argues that may not be the norm in the noisy, sex-crazed forest ponds from Mexico to Venezuela where these mating rituals take place. In a series of experiments, researchers broadcast male calls to female túngaras. When the females heard just two calls, they unsurprisingly hopped towards the one they found more inviting. When the scientists played those same two calls plus a third even more inferior one, the females instead chose the intermediate call, falling prey to the “decoy effect,” the researchers report online today in Science. (The decoy effect works on humans, too: When buying a used car, for example, consumers who value a lower price over fuel efficiency may choose car B over car A, which costs more but has superior efficiency. But when another car, C, also with good fuel efficiency but at a much higher price than either A or B is added to the mix, consumers often change their mind and choose car A.) For the túngaras, such “irrational” behavior could be the result of females feeling pressure to make a decision quickly to avoid lost mating opportunities or predators like bats. At least one species of bat is known to use echolocation to pick up on the ripples created in the pond by the male frogs inflating and deflating their vocal sacs while calling. The findings could improve our understanding of animal mating and may point to deeper biological roots for the decoy phenomenon, the scientists say.last_img

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