Sunday, October 11, 2009

Frogs in Australia

This post is really just gratifying my inner science nerd, but it has to do with sonic phenomena, so I can justify its being here -or, that's my story, at least.

Australia's Frogs are having a hard time hooking up. Male brown tree frogs meet their girls by vocalizing elaborate mating calls. The sound of the male looking for a date hits the ears of the female tree frog and she chooses weather or not to pursue the guy -or that's how it's supposed to work. But lately, there's been some interruptions. Traffic noise and other sounds of city life, like air conditioners and construction noise, are drowning out the mating calls of male frogs in urban areas. These guys can sing their hearts out, but add the sounds of nearby traffic, and the serenade never reaches the female. The distance over which the male frog can be heard is cut dramatically by traffic noise from hundreds of meters, in some instances, down to maybe only 20 or 50 meters. Consequently, these frogs aren't hooking up and their population has seen a sharp drop recently.

Remarkably, some of these persistent Romeos have come up with an interesting strategy for making themselves heard. They're changing their calls to a higher, squeakier pitch, increasing the distance over which they can be heard. One would think this is the solution, right? Survival of the fittest? But the Juliets out there don't seem to agree. While the males have figured out how to make themselves heard above the noise of the city, scientists say this just may not be what the females are looking for. When females have a choice between two males calling, they tend to select the one that calls at a lower frequency because, in frogs, the frequency of a call is related to body size (So, the bigger frogs tend to call lower, and well, that's very attractive in a frog, apparently). In other words, the high talkers typically don't get the girls. Yes, brutally unfair, but true. Personally, I prefer tenors...

Nights in Aussie are noisy nowadays and female frogs can only hear a few of the males that are all calling in a group. So the number of mates she can choose from is reduced. The scientists describe it like being in a noisy cocktail bar and there are men everywhere. You can only see and hear the three that are closest to you. You either choose to go with one of them, or you spend more energy going to search the room to find someone who looks a little bit more promising. This results in the females doing quite a bit more hopping around, and the longer they spend looking for mates, the more time they're exposed to predators and the more energy they use. Not the best situation and infinitely more frustrating for those girls, I'm sure.

Yep, a bit of depressing news. But didn't even John Cage acknowledge the meddlesome nature of humans in his How to Improve the World: You Will Only Make Matters Worse? I'm sure no one took the time to consider the love lives of nearby frogs when they installed that new air conditioner. How thoughtless of us!

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