An observational study showed that wild animals can predict earthquakes at least three weeks before the actual strike.

Researchers at Anglia Ruskin University in Britain observed the camera traps installed at the Amazon and noticed the movement changes of the wild animals at least three weeks prior to the magnitude 7.0 earthquake that hit the region in 2011. Twenty-three days before the earthquake, the team saw that the number of animal movements significantly dropped by two-thirds, or from the regular 15 sightings to less than five per day. Seven days before the earthquake, they recorded zero sightings indicating that the wild animals might have migrated somewhere safer.

"Animals have the potential to be reliable forecasters of earthquakes and could be used alongside other monitoring systems," Rachel Grant, lead author of the report and lecturer in Animal and Environmental Biology at Britain's Anglia Ruskin University, told Reuters.

"The system could be used in developing and earthquake-prone countries, it is affordable and feasible to implement as it just requires someone to monitor animal behavior... there is no need for satellites."

The researchers believe that animals' bodies detected the atmospheric changes weeks before the earthquake. These changes triggered an increase in the serotonin levels in the bloodstream of these animals that resulted in restlessness and confusion. Scientists added that humans also experience the same fluctuations, also known as the "serotonin syndrome," but the effects are more evident in animals.

"The results are particularly interesting as we also found evidence of disturbances in the ionosphere in the area where the earthquake struck," Grant told Mirror UK.

"We believe that both of these anomalies arise from a single cause: seismic activity causing stress build-up in the earth's crust, leading - among other things - to massive air ionization."

The study is the first to link animal movement to earthquakes. The findings can be helpful in the improvement or creation of more affordable and more reliable earthquake early warning systems. 

The study was published in the March 24 issue of the journal Physics and Chemistry on Earth.