Study: Toads May Detect Coming Earthquakes

British researchers said Wednesday that they observed a mass exodus of toads from a breeding site in Italy five days before a major tremor struck, suggesting the amphibians may be able to sense environmental changes, imperceptible to humans, that foretell a coming quake.
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Researcher Rachel Grant said the findings suggested "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."
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She said one possibility is that the animals sensed a change in the amount of radon gas emitted by the Earth because of the buildup of pressure prior to a quake.

Scientists also have surmised that animals may be able to detect minor tremors imperceptible to humans, or that they sense electrical signals emitted by rocks under stress before an earthquake."