Who knew frogs needed a certain ambiance to get them in the mood? Dr. Kirsten Parris, a Melbourne University ecologist, has discovered that noise from traffic and machinery may be a contributing factor in the decline of urban frogs in Melbourne.
After all, the frog’s croak is one of the most important attributes when it comes to attracting females to their pond. But a new study reveals that all that noise may be drowning out the mating calls of the frog.
Female frogs often perceive males with the loudest and quickest love songs to be the most fit and attractive, according to Parris. When several frogs croak at the same time, females are usually attracted to the frog that sounds the best.
But due to urban noise, the distance the croak can be heard is diminished. In the noisiest of neighborhoods, frogs using their normal pitch can’t be heard past 21 yards while frogs using higher pitches can be heard up to 37 yards. Without the noise of the traffic and machinery, popplebonk frogs can be heard by females at distances up to 875 yards. But add in some traffic and other noise, and the distance is reduced to only 46 feet!
Parris said the males are exerting more energy cooing their mates, using higher pitches to drown out the low frequency of the traffic. Southern brown tree frogs have raised the pitch of their voices in order to adapt to the noise. And frogs with low-pitched croaks have an even bigger disadvantage because they are competing against the low-pitched noise from traffic and other types of machinery.
Parris has been studying 104 ponds since 2000. She discovered populations of frogs have disappeared and the number of species in each pond has also been reduced. Parris, along with Melbourne Zoo and Royal Botanic Gardens Melbourne, are working on a pilot program to breed frogs and then release them into empty ponds. Parris presented her findings last week to the 10th International Congress of Ecology, INTECOL.
Photo: Green Tree Frog LiquidGhoul via Public Domain
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