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Common toad, Bufo bufoA paper in this month’s Journal of Zoology (1) suggests that the common toad, Bufo bufo, can possibly do just that. The ability to sense a coming earthquake has been suggested for many animals, but scientific proof is thin on the ground. A team monitoring toad mating behaviour in Italy in 2009, however, happened to record their data before, during and after an earthquake struck 74km from the study site. During previous years, once the toads started mating they would continue until the spawning season had finished, but in the year of the earthquake 96% of male toads disappeared from the site five days before the earthquake struck (the sample size of females was too small to analyse), and male toad numbers remained lower than usual until two days after the last aftershock. Fresh spawn (toad eggs) was seen six days before the main earthquake, and six days after it, but none was seen during the intervening earthquake period.

Toad behaviour is correlated closely to weather, but this male site-desertion did not correlate to maximum or minimum temperature, percentage humidity, wind speed, or rainfall – it did, however, correlate to the number of days before or after the earthquake (and the earthquake period), and the number of mating toad-pairs similarly correlated with days before or after the earthquake and earthquake period.

Common toad, Bufo bufo, mating pair (by HotShot²)How the toads predicted the earthquake is unclear but the authors suggest that they perhaps responded to a change in the Earth’s magnetic field (toads have been shown to react to geomagnetic fields in previous research), or to a rise in radon gas in the groundwater (which can occur before a big earthquake – again, toads are sensitive to changes in water chemistry), or to some other unidentified change to the ionosphere (one of Earth’s atmosphere layers). However they do it, it certainly seems that these toads could detect some sort of change in the ionosphere that allowed them to predict the earthquake was coming and move to safety before the earthquake struck, which is pretty amazing.

 

References

  1. Grant RA & Halliday T 2010 ‘Predicting the unpredictable; evidence of pre-seismic anticipatory behaviour in the common toad’. Journal of Zoology 281: 263-271

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