TX Press: Frog Croaks, Population Weakened By Traffic Noise

[Herp News]

RED ORBIT (Texas) 21 August 09 Frog Croaks, Population Weakened By Traffic Noise
Male frogs living near urban areas are having trouble competing with the sound of the city, which may be causing the frog population to decline.
Male frogs use their croaks to attract their mates. But Melbourne University ecologist Kirsten Parris found that the frogs face a tough task in trying to overpower the loud noise from nearby traffic.
"If there are a number of different males calling, the one that sounds the best often gets the girl," Parris told The Associated Press. "You have to be pretty clear about your assets if you're a male frog."
"Generally, if he's putting a lot of energy into calling — if he's calling loudly or quickly or for a long time or all those things combined — it shows he's fit and strong and generally those things tend to correlate with female choice," she added.
Parris presented her study at the 10th International Ecology Congress in Brisbane.
Frogs with low-pitched croaks are the most likely to be affected by the city noise, which Parris says has the ability to squelch any nearby suitors.
However, Parris found that the southern brown tree frog has learned to adapt its pitch to be higher in louder areas. The higher pitch allows the croaks to be heard from an extra 16 feet more than their normal pitch.
Parris noted that the croak of the popplebonk frog can be heard from 875 yards without the city’s white noise, but with the city noise the frog’s call can only reach about 46 feet.
"There is accumulating evidence that noise in urban habitats is having an effect on the behavior of animals," University of Sheffield ecologist Ken Thompson told the AP.
“Where year after year there's not enough water for them to breed, eventually the frog population will decline to nothing and then in cities where there's a lot of roads and other things in the way, other frogs can't come and move back into those ponds so they stay empty,” Parris told the Australian Broadcasting Company.
http://www.redorbit.com/news/science...urce=r_science