Positive Ion Emission Before Earthquakes May Affect Animals
Both folklore and modern observations are emphatic that many animals become agitated prior to earthquakes. Cats car-ry their kittens outdoors; cattle panic in their barns; dogs bark for no apparent reason; and even some humans become restless. Tributsch notes that similar behaviors also accompany certain weather situations, such as the Alpine foehn and Near East sharav, which are characterized by high concentrations of positive ions. The unusual "fogs" and luminous displays preceding some earthquakes may also have electrical origins. In essence, Tributsch has reviewed many earthquake precursors and suggests that most can be explained in terms of positive ion emission from the earth due to pre-quake strains.
(Tributsch, Helmut; "Do Aerosol Anomalies Precede Earthquakes?" Nature, 276: 606, 1978.)
Reference. Even humans are sensitive to "earthquake weather." See Section GQW in: Earthquakes, Tides. Unidentified Sounds. More information on this Catalog volume here.