Toads may be able to detect imminent earthquakes, according to scientists. The finding will add to the accounts through the centuries where animals, from dogs to rats, snakes and chickens, are said to have behaved strangely before an earthquake.

In the study published today in the Journal of Zoology, a colony of toads deserted their mating site three days before an earthquake struck L'Aquila in Italy last year – the epicentre was 74km from the area where the animals had normally gathered. No toads returned to the site until 10 days later, after the last of the significant aftershocks had finished.

The discovery was made by accident by Rachel Grant, a life scientist at the Open University. She was studying the effects of lunar cycles on the toads' behaviour and reproduction. "I was going out every evening at dusk and counting how many toads were active and how many pairs there were. Normally they arrive for breeding in early March and you get large numbers of males at the breeding site. The females get paired fairly quickly. They stay active and obvious around the breeding site until the spawning is over in April or May."

One day she noticed there were no toads. "Sometimes during the breeding season you get a drop in numbers if there's been a very cold night but usually, the day after, they come back again. It was very unusual that there was none at all."

There could be several mechanisms for animals to sense the beginnings of an earthquake, wrote Grant in the Journal of Zoology. They could detect seismic waves directly or ground tilt (which can occur in the minutes before a quake). In addition there might be anomalies in the Earth's magnetic field.

Looking for clues to explain the toads' behaviour, Grant found that scientists had noticed disruptions in the ionosphere, the uppermost electromagnetic layer of the earth's atmosphere, at the time of the L'Aquila earthquake, which the toads may have detected. Previous earthquakes have had similar ionospheric disruptions associated with them. "I've spoken to seismologists who said there were a lot of gases released before the earthquake, a lot of charged particles. Toads and amphibians are very sensitive to changes in environmental chemistry and I think these gases and charged particles could have been detected by the toads."

Previously, fish, rodents and snakes have been anecdotally associated with unusual behaviour more than a week before an earthquake or at distances greater than 50km.

In 2003, Japanese doctor Kiyoshi Shimamura found that there was a jump in dog bites and other dog-related complaints before and after earthquakes. Before the 1995 earthquake in Kobe, a disaster that killed more than 6,000 people, he found that accounts of dogs barking "excessively" went up by 18% on average in the months before the earthquake. Above the epicentre on Awaji Island, there was a 60% increase in complaints compared with a year earlier.

Grant's work is not the first time toads have been associated with sensing the precursors of earthquakes. "In 2008, there was a big earthquake in Szechuan province in China and there was unusual migration of toads seen," she said. "I'd like to study it further and look at animal behaviour in combination with seismological and geophysical precursors."