LONDON — When it comes to predicting earthquakes, toads may be an asset, warts and all.

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 quake.

Since ancient times, anecdotes and folklore have linked unusual animal behavior to cataclysmic events like earthquakes, but hard evidence has been scarce. A new study by researchers from the Open University is one of the first to document animal behavior before, during and after an earthquake.

The scientists were studying the common toad — bufo bufo — at a breeding colony in central Italy when they noticed a sharp decline in the number of animals at the site. Days later, a 6.3-magnitude earthquake hit, killing hundreds of people and badly damaging the town of L’Aquila.

“A day after the earthquake, they all started coming back,” said researcher Rachel Grant, the report’s lead author. “The numbers were still lower than normal and remained low until after the last aftershock.”

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.”

The study appears in the Zoological Society of London’s Journal of Zoology.