London, Apr 18 (IANS): The long-held belief that strange behaviour by cats, dogs and even cows can predict an imminent earthquake is not backed by evidence, according to a new study.

Such claims are often based on single observations and anecdotes that cannot be tested rigorously, showed the research published in the journal Bulletin of the Seismological Society of America.

To explore the link between the animal behaviour and earthquake, the researchers studied 729 reports of abnormal animal behaviour related to 160 earthquakes.

"Many review papers on the potential of animals as earthquake precursors exist, but to the best of our knowledge, this is the first time that a statistical approach was used to evaluate the data," said researcher Heiko Woith from GFZ German Research Centre for Geosciences.

The researchers collected reports on potential earthquake predictions across a variety of animals, from elephants to silkworms.

Most reports were anecdotes rather than experimental studies, and the majority of the reports came from three events -- the 2010 Darfield earthquake in New Zealand, the 1984 Nagano-ken Seibu earthquake in Japan, and the 2009 L'Aquila earthquake in Italy, the researchers found.

The unusual behaviours occurred anywhere from seconds to months prior to the earthquakes, and at distances from a few to hundreds of kilometres from the earthquake origins.

These weaknesses in the data make it difficult to confirm that these behaviours are predictive - meaning they signal an earthquake event before the event begins - rather than random occurrences or behaviours linked to the initial stages of an earthquake, such as foreshocks, the study said.

The animals may sense seismic waves generated by foreshocks, Woith suggested.

"Another option could be secondary effects triggered by the foreshocks, like changes in groundwater or release of gases from the ground which might be sensed by the animals," he added.

One of the biggest problems with the animal data, Woith said, is the lack of continuous, long-term observations of animals experiencing earthquakes.

"Up to now, only very few time series with animal behaviour exist at all, the longest being just one year," he said.