Thursday, January 17, 2013

Traffic Noise

We recently posted on grasshopper mating including studies of a species which produces louder calls when living along busy highways, attracting mates over the competing sounds of traffic.  Our Master Naturalist Bob Korpella posted a similar story about birds on Freshare.net. To quote his source from the Max Planck Institute:
"To attract mating partners and defend their territories, urban robins sing later in the night, once traffic noises decrease after the evening rush. Many other bird species, including blackbirds, sing in urban environments at a higher pitch, so that their song is easier to distinguish in the lower-frequency traffic noise."
National Geographic
Like young people at a loud party, communication has to get above the ambient noise.  For the most part, birds are faced with a more constant sound, unlike the constantly changing background of a DJ's selections.  And like humans dancing, they learn their own moves to attract a female's attention.  The highest points for style go the the Bird of Paradise as seen in this video.

Probably the most athletic is the Golden-collared Manakin.  As you can see in this video, he leaps between parallel branches, using his wings only to soften the landing, and even throwing in a back flip from time to time.  During these athletic moves, its heart rate jumps from its normal 600 beats per minute to an astounding 1300 beats per minute (21 beats a second)!
“The females pre­fer the males that pe­r­form the el­e­ments of the dance faster and dem­on­strate bet­ter mo­tor co­ordina­t­ion,” said lead au­thor Jul­ia Bar­ske, a grad­u­ate stu­dent and doc­tor­al can­di­date at the un­ivers­ity. “Females pre­fer more ac­tive males that do more court­ship ac­ti­vity.”

“Jul­ia’s da­ta show that the females se­lect the males that com­plet­ed el­e­ments of the court­ship dance in 50 mil­lisec­onds (thou­sandths of a sec­ond) over the males that took 80 mil­lisec­onds,” Schlin­ger added. "  World-Science.net
Different species have different styles and hopefully always will.  The thought of a collection of different bird species dancing Gangnam Style in our yard is too horrible to contemplate.

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