Susan Cosier, livescience.com Yahoo News 31 Mar 10;
Predicting an earthquake is notoriously difficult, yet before the ground shakes, some animals reportedly jump into action, from birds flying in unusual directions to dogs becoming restless during those pre-quake hours to days.
Most of these tales, however, aren't backed up by scientific data, until now. Breeding toads might be able to notice subtle changes in the environment before an earthquake, allowing them to flee the scene and hop to safety, according to a new study announced today.
The study researchers found that common toads (Bufo bufo) abandoned their breeding grounds five days before an earthquake struck L'Aquila, Italy, in April of 2009. The toads didn't return for a few days after the tremor, something they almost never do.
The team also found that disturbances that occurred in the upper atmosphere before that quake correlated with the toads' movements.
"It's the first time that any study has really documented unusual behavior before an earthquake in a scientific and methodical way," lead study author Rachel Grant, a zoologist from The Open University in the U.K., told LiveScience. "We did it properly and scientifically, and consistently looked at behavior."
A fair shake
The team was studying the effect of the lunar cycle on the toads, which only breed during one month a year in a shallow pool on an Italian lakebed, when they noticed the seismic behavior. Over a 29-day period, Grant and her colleagues had been watching the toads at their breeding site, and got the opportunity to see them before, during, and after the quake.
Five days before the earthquake, after spawning had just begun, the number of male toads at the site decreased by 96 percent. Six days after the last significant aftershock, the toads came back and produced the rest of their spawn.
"So they had two spawning periods, which is really unusual," said Grant.
Toads are highly sensitive to weather changes, yet no odd weather occurred before the earthquake that would have led to the exodus of toads from their breeding grounds. What did change, however, were the Earth's magnetic field and the amount of radon gas in the groundwater, which the planet's crust burped out before the earthquake.
The researchers aren't sure which factor might have caused a disturbance in the upper atmosphere that was detected using very low frequency (VLF) radio sounding. Whatever the cause, the toads' reactions suggest the amphibians can sense the difference and take action to protect themselves.
Quake prediction
An earthquake detector could be particularly beneficial to toads, which move slowly and so can take hours or even days to find an area that won't be affected by a flood or a mudslide. And postponing their breeding to avoid the disaster could result in greater reproduction success, said Grant.
"I was really surprised because I wouldn't think that earthquakes would be that dangerous to toads, but the fact that they disappeared indicates that they are," said Grant.
Determining the exact reason for that response, however, would be extremely difficult because no one knows when earthquakes will happen. The knowledge that toads can anticipate them, however, could prove beneficial in the future, said Grant.
"One day there could be a system involving amphibians as an early earthquake predictor in combination with other seismic indicators," she said.
The study is detailed in a recent issue of the Journal of Zoology.
Toads with a super sensitive side hopped it before L'Aquila quake
Colony of amphibians vanished from Italian lake five days before disaster, then returned to breed when it was safe
Steve Connor, The Independent 31 Mar 10;
The common toad may be ugly, warty and squat, but it is blessed with an extraordinary gift. It has an uncanny ability to predict earthquakes several days before they occur, according to a remarkable study that documents for the first time an extraordinary "supersense" in wild animals.
Scientists studying a colony of breeding toads living in an Italian lake found that they suddenly disappeared en masse five days before a magnitude 6.3 earthquake struck the town of L'Aquila in central Italy in the early hours of 6 April 2009. Most remarkably, L'Aquila is 74km (46 miles) from the lake.
The researchers behind the observations believe there is no explanation other than the fact that the toads must have been able to detect some changes in their environment which led them to believe that violent tremors were imminent. Within days of the earthquake, the toads had returned to their breeding pool to continue spawning.
Anecdotal reports of animals behaving strangely before an earthquake are not unusual, but most cannot be properly assessed scientifically because they rely on eyewitness accounts after the event. In this case, however, the scientists were monitoring the toads long before the earthquake happened.
"Our study is one of the first to document animal behaviour before, during and after an earthquake. Our findings suggest that toads are able to detect pre-seismic cues such as the release of gases and charged particles, and use these as a form of earthquake early warning system," said Rachel Grant of the Open University in Milton Keynes.
"We looked at the weather and other possible causes of the sudden disappearance of the toads, but nothing seemed to fit. There didn't seem to be any other reason for it except that they had somehow managed to sense that an earthquake was going to happen," Dr Grant said.
The lake where the toads were breeding was being monitored nightly by Dr Grant and her Italian colleagues, who were studying the effect of moonlight on amphibian behaviour. Males of the common toad, bufo bufo, collect in large groups of up to 100 individuals to mate with passing females.
One night, Dr Grant found that the number of males had fallen dramatically, which she thought may be due to cold weather. However, for the next five nights, she failed to find a single toad, which was unprecedented.
"They could have gone back up into the high ground around the lake or they could have dug into the mud – we don't know," she said.
Russian scientists suggested that the toads may have been able to detect the release of radioactive radon gas from the ground, or the presence of charged particles in the ionosphere of the night sky, Dr Grant said. If so, it may be an evolved ability to protect the slow-moving animals from the frequent mud slides caused by earthquakes, she added.
"There could be more evolutionary pressure on them to develop an effective early seismic escape response," she said.
The study is published in the Journal of Zoology.
Animal magic: How they beat humans
* Kestrels can see ultraviolet light which helps them detect voles, their favourite prey.
* Homing pigeons can detect the Earth's magnetic field to allow them to navigate over long distances.
* Lions often hunt at night, because their eyes can see about seven times better in the dark than humans.
* Fish use their skin to detect movement and vibrations in water, in the same way people can feel breezes.
* Sharks can smell a single drop of blood diluted in 100 litres of water.
