Female Treefrogs Get Overwhelmed by Too Many Noisy Male Suitors

A chorus of male frogs advertising their wares to females can be quite the cacophony. In fact, it’s such a racket that you have to wonder how a female can distinguish the calls well enough to make a sound choice (pun intended)—something a study led by University of Tennessee biologists recently investigated. 

In a prior study, female Cope’s gray treefrogs (H. chrysoscelis) preferred males with longer calls, likely perceiving duration as an indicator of fitness. If the environment got too noisy with chorusing males, however, females lost their ability to choose a fit male. The interference could be caused simply by experiencing too much noise, or from being overwhelmed by too many choices. 

“In human terms, is it like entering a crowded bar and not being able to hear anyone talk, or is it like using a dating app and not being able to choose among the many options?” wondered lead author Claire Hemingway in a press release.

Read more: “Maybe Playing Dead Will Get Him to Leave You Alone?”

To distinguish between noise saturation and choice overload in gray treefrogs, Hemingway and her collaborators played recordings of mating calls to 52 females collected from the wild. Each female heard one favored mating call—a long-lasting trill, combined with either one, three, or seven shorter “distractor” calls. In addition, each combination was tested with either silence or a gray treefrog chorus in the background. 

A female was counted as choosing a call if she approached within 4 inches of a loudspeaker. If choice overload had a larger effect, the researchers expected the females’ choice of the best mate to decline, no matter the background sound. Conversely, if too much noise had a larger effect, they figured the background of chorusing frogs would impair females’ choice of the favored male.

In the end, as the number of calls increased, females became less accurate in selecting the favored long-duration call, no matter the background noise. With just two males calling, a female found the fitter mate 76 percent of the time, whereas with eight calling males, she stalled in her decision-making and then selected the “fitter” mate only 25 percent of the time.

“With or without noise, when we presented more calls to the females at once, their performance declined in several ways, making the effect of choice overload clear,” said senior author Jessie Tanner. 

It’s actually kind of comforting to know that we’re not the only species that struggles with making the right dating choices. 

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Lead image: Samuel / Adobe Stock