article_snippet: Researchers believe that the changes in behaviour may be linked to airborne ions.
article_snippet: It is thought that positive airborne ions, which are known to be generated in large numbers at the Earth’s surface when rocks deep below are subjected to increasing stresses during the build-up to an earthquake, trigger unusual animal behaviour.
article_snippet: Positive ions in the air lead to unpleasant side effects in animals and humans, such as ‘serotonin syndrome’.
article_snippet: Prominent among the most likely causes for the unusual animal response are positive airborne ions, which are known to be generated in large numbers at the Earth’s surface when rocks deep below are subjected to increasing stresses during the build-up to an earthquake.
article_snippet: Positive ions in the air lead to unpleasant side effects in animals and humans, such as ‘serotonin syndrome’.
article_snippet: hyperactivity and confusion expected the injection of positive airborne ions into the Earth’s atmosphere before seismic activity to have a profound effect on mammals and birds - in particular those living on the ground and in burrows, and the study seems to prove this.
article_snippet: Hence, the animals would have escaped to the valley below, where the animals were exposed to fewer positive airborne ions.
article_snippet: Prominent among the most likely causes for the unusual animal response are positive airborne ions, which are known to be generated in large numbers at the Earth’s surface when rocks deep below are subjected to increasing stresses during the build-up to an earthquake.
highlights_snippet: Study suggests animals respond to disturbances in the ionosphere .
  
highlights_snippet: Positive ions in the air lead to disagreeable side effects in animals .