Camera traps in Peru's Yanachaga National Park in Peru have shown an "amazing" drop in animals numbers up to 23 days before a major quake.
Before the magnitude seven Contamana earthquake in 2011, no animal movements were recorded for five of the seven days leading up to the tremor.
That is extremely unusual in a region with abundant wildlife.
Lead scientist Dr Rachel Grant, from Anglia Ruskin University, said: "The park was 320km from the epicentre, and I thought, there was not much going to be happening. But when I saw the results I was totally shocked. It was amazing. The analysis showed that just before the earthquake animal activity dropped right down."
It is thought positive ions - electrically charged molecules said to be generated when rocks are placed under stress - were released into the air at the mountain site prior to the quake
These ions are believed to make the animals, mainly rodents and other creatures living close to the ground, feel uncomfortable and leave the area.
They are believed to have moved to lower ground where the air will have less ions.
Unlike "feel good" negative ions, positive ions can trigger headaches, agitation, hyperactivity and confusion in humans as well as animals.
When seismic activity was low, a study of camera trap sightings showed that animal activity remained normal in the park.
Researchers claim the findings may help to develop better short-term seismic forecasts.
Story & picture from Skynews