Tiny tree frogs in urban Taiwan have been using the city's storm drains to amplify their mating calls.
These storm drains are usually built on the side of roads. Researchers determined the frogs have been seeking out these "urban canyons" to make their mating calls farther reaching, a Wiley news release reported.
"This is perhaps the first study to show that an animal preferentially uses human-made structures to potentially enhance the sounds of its vocal communication signals," Mark Bee, a biologist at the University of Minnesota, Twin Cities, told Nature. "These males could be taking advantage of the enhanced acoustics in drainage ditches to outdo their competition."
Males of the Kurixalus idiootocus species form groups that compete for females by singing, Nature reported. The mating season lasts from February through September.
The researchers monitored these pipes and surrounding areas to see what happened after dark. They found the frogs chose these drainpipes much more often than other places. They took audio recordings of the frogs' calls to determine if they were louder and longer when emitted within the storm drains.
The calls emitted inside of the drain were much louder than those outside, they also had longer durations. These calls were found to be at least four decibels louder than those of frogs outside of the pipes and were found to be 10 percent longer. This phenomenon could make female frogs more likely to choose the louder males.
The researchers were not able to definitively determine if these frogs were more successful with the ladies than the ones that did not amplify their calls.
Further studies will be necessary in order to determine if these frogs specifically hop into storm drains in order to increase their chance of finding a mate. The frogs could be doing this in an attempt to avoid predators.